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About this book

This book presents selected papers from the International Conference of Aerospace and Mechanical Engineering 2019 (AeroMech 2019), held at the Universiti Sains Malaysia's School of Aerospace Engineering. Sharing new innovations and discoveries concerning the Fourth Industrial Revolution (4IR), with a focus on 3D printing, big data analytics, Internet of Things, advanced human-machine interfaces, smart sensors and location detection technologies, it will appeal to mechanical and aerospace engineers.

Table of Contents

Frontmatter

A Review on Alternative Fuel Spray Characteristics

Air transport is already a well-known transportation in assuring the need of worldwide social connection and commercial purposes. Nowadays huge demand on aviation fuel increases severe tense due to depletion of fossil fuel. Furthermore, the increases of greenhouse gas emission from the fossil fuel reduces the environment quality and human life. Hence, an attention towards alternative aviation fuel from renewable sources has become a priority as it could offer greener aviation. However alternative fuel must be compatible in comparison of the conventional fuel in terms of its physical properties such as viscosity, energy density, sustainability, affordability and availability. Those properties will affect spray characteristics and leads to combustion quality. Therefore, this study presents a review on the different alternative fuels and their compatibility in the aircraft engine. The importance of spray characteristic on the engine and different experimental approach to examine the spray characteristics of fuel particularly the penetration length, spray morphology, cone angle and atomization of the fuel also are presented. This work is beneficial in providing understanding on alternative fuels and spray atomization examination.

Qummare Azam, Ahmed M. Alhaj, Ayub A. Janvekar, Nurul Musfirah Mazlan

Modelling of Crack Propagation for Embedded Crack Structure

Inner or embedded cracks were created in the structures of nuclear power plant by fatigue after years of operation time. Embedded cracks which generated in nuclear power plant is modelled as circular cracks in a plane normal to tension loading direction in Probabilistic S-version Finite Element Model (Prob-SFEM). Prob-SFEM which can generate the model with fatigue loading and crack growth due to number of fatigue cycle realistically by using uncertainty parameters from Monte Carlo method. Fatigue life and crack growth were generated from ProbS-FEM simulation. A simple model for embedded cracked structure was shown in this paper. Crack propagation of the embedded crack was analyse using deterministic S-version Finite Element Model and ProbS-FEM. Comparison between those two methods were investigated in this paper.

H. A. Haziq Aiman, M. R. M. Akramin, M. N. M. Husnain, M. S. Shaari

Mitigation of Carbon Footprint of an Airport in the Kingdom of Saudi Arabia

Aviation is a major source of carbon emissions and this industry is growing at a fast pace, drawing the attention of environmentalists. In addition to being a large source of carbon emissions, aviation is also responsible for the deterioration of air quality, noise pollution and consumption of water resources. With the Kingdom of Saudi Arabia (KSA) being the largest country in the middle east, aviation is a major means of mass transport. The number of air travelers is increasing exponentially, resulting in a serious threat to sustainability, with both climate change and the environment in perspective. The per capita carbon footprint of KSA is among the top 20 countries in the world. In this study, an international airport in KSA has been considered with its carbon footprint estimated for 2016. Airports are purposefully located outside the city and require large construction free land for the purpose of security and airport activities. Thus, an airport provides ample space and opportunity to be used for energy harvesting and carbon mitigation. In this work, a three-tier process to neutralize the carbon emissions of the airport has been suggested to transform it into a carbon-neutral airport. The reduction of carbon emissions suggested in this study includes a reduction in emissions, promoting renewable energy, and carbon capture and storage. The proposed methods complement each other and enable a 360° approach for carbon mitigation.

Vineet Tirth, Saad AL-Mashhour, Mustafa Al-Ani, Mohannad Alqahtani

Error Analysis on Galerkin Scheme for the Diffusion Problem

For advection-diffusion problem, the non-unified approach of classic residual distribution (RD) schemes for advection discretization and pure Galerkin scheme for diffusion discretization has seen accuracy degradation and previous work has dealt with the accuracy analysis of the advection part on various RD schemes. The current work focuses on the accuracy analysis on diffusion discretization scheme of pure Galerkin method with the effect of grid skewness variation. Analytically, the accuracy of the pure Galerkin method is analyzed rigorously with Fourier expansion technique for pure diffusion problem in right-running grid with the introduction of grid skewness parameter as a variable. The truncation error study shows that pure Galerkin scheme is second order accurate in space with minimal or no effect from the variation of skewness. Numerical tests were performed on both steady and unsteady diffusion problems and the outcome matches the analytical study. Additional numerical test on randomized grid revealed that the analytical claims on uniform grid can be extended to poor quality grid. This work suggests that the diffusion discretization using pure Galerkin scheme is not the main factor of the degradation of the accuracy of the non-unified RD-Galerkin scheme.

Wei Shyang Chang, Haswira Hassan, Hazim Fadli Aminnuddin, Vishal Singh, Farzad Ismail

Design and Modeling of Actuation System of Unmanned Tricopter with Thrust-Vectoring Front Tilt Rotors for Sustainable Flying

Tilt rotor aircrafts combine the advantages of the long mileage of fixed-wing airplanes and the vertical take-off and landing (VTOL) capabilities of rotorcrafts by using tiltable rotors. However, tilt rotor aircrafts suffer from poor autorotation performance and landing stabilitiy. This work proposes an alternative actuation configuration of a tricopter tilt rotor aircraft that aims to optimize the flight duration, VTOL capabilities and stability control. The proposed configuration employs two front tilt rotors that are able to provide thrust-vectoring control with the addition of a fixed tail rotor that produces upward thrust. Dynamic modeling of the proposed actuation configuration is developed to provide insights on how different motions (hovering, ascending, descending, rotating and airplane-like flying) are achieved by manipulating the amounts of thrusts and rotor tilt angles. Preliminary prototype as well as the electronic and control systems are developed and discussed. Proposed configuration has the potential to achieve more sustainable flying.

Riady Siswoyo Jo, Aaron EuGene Tan, Mark Tee Kit Tsun, Hudyjaya Siswoyo Jo

Design of an Air-Duct Pipe Inspection and Cleaning Robot

Air-ducts are one of the important elements in a building for making the living environment safe and healthy by ensuring smooth flow of fresh air, often cool air-conditioned, into rooms and spaces inside buildings. Often, over time, the air-ducts and vents can be unclean with dusts, dirt and contaminants. This can affect the performance and efficiency of the heat, ventilation and air conditioning (HVAC) system, and more importantly the people’s health. Manual cleaning of the air duct usually very challenging, tedious and time consuming. Considering these conditions, an in-pipe robot that can move along air-duct piping to carry out inspection and cleaning work is designed. This paper describes the design process that was carried out, started out with developing the design requirements and intended functions of the robot. A 3D model was developed using Creo software and stress analysis were conducted. The final design of the robot was produced, utilizing Arduino Uno as the main microcontroller, eight servomotors for the actuators and multiple pressure sensors are used to assist in the navigation and motion.

Adzly Anuar, Juniza Md Saad, M. N. A. Arimi

Investigation of Variable Geometry Intake to Mitigate Unwanted Shock-Shock Interactions in a Hypersonic Air-Breathing Propulsion Device

Recently there has been a resurgence of interest in achieving practical hypersonic flight especially since China and Russia has announced successful demonstration of their military technology. The key enabler for hypersonic is the scramjet engine as the air breathing propulsion device. Engineering design of a scramjet intake is crucial since unwanted shock-shock interactions inside the intake could impede safe combustion process. In this study, we demonstrate that minimal geometry modification of the intake could significantly increase its performance. A generic scramjet intake that performs sub optimally is shown to benefit greatly by having its cowl deflected inwards at small degree. Pressure-sensitive paint measurement showed that peak pressure due to adverse shock-shock interactions at cowl tip has been reduced significantly.

Azam Che Idris, Mohd Rashdan Saad, Konstantinos Kontis

Enhancing Productivity of Solar Still with Pyramid Chamber Step-Wise Basin Design

Improving the performance of the traditional single slope solar still is a pressing need. In this paper, modifications were introduced to the pyramid design, where it has three different faces, and has a Step-wise chamber. Experimental studies were performed in winter where the following interesting results are achieved: the production rate of distilled water of the modified design is up to 85% higher than the traditional design; in addition, temperature gain is 25% higher than traditional design.

Salah Abdallah, Hanan Saleet

Mechanical Characteristics of Paraffin Wax-HTPB Based Hybrid Rocket Fuel

Paraffin wax has 3–4 times higher regression rate compared to conventional polymeric fuels used in hybrid rocket applications. Hydroxyl-terminated polybutadiene (HTPB) suffers poor mechanical properties and has lower tensile strength, Young’s modulus compared to pure paraffin wax. The mechanical properties of HTPB can suitably be improved by mixing paraffin wax with HTPB. In this study, paraffin wax and HTPB are mixed with different weight ratios to form nine different compositions viz, 100P, 90P, 80P, 70P, 60P, 50P, 40P, 25P and 0P (where P denotes the percentage of paraffin wax and the remaining forms the HTPB system). To understand the effect of addition of paraffin wax with HTPB, nine fuel samples were prepared and experimentally tested for their mechanical properties. It is observed that addition of paraffin wax content in solid fuel composition increases maximum stress and Young’s modulus in the range of 16–74% and 15–97% respectively. It is also observed that addition of paraffin wax content in solid fuel composition decreases percentage of elongation by 98–57%. The surface morphology and chemical composition were examined using Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) to understand the blending of paraffin wax + HTPB and to find out the occurrence of chemical reaction during mixing and curing processes.

Sri Nithya Mahottamananda, P. N. Kadiresh

Aerodynamic Performance of Shark Skin Shape Vortex Generator

The performance of NACA 4415 airfoils with counter rotating triangular or shark skin shape sub-boundary layer vortex generators were evaluated. This is relevant to the improvement of lift-to-drag ratio of the airfoil which will contribute to development of a more efficient airfoil. The lift and drag coefficients of NACA 4415 airfoils without vortex generator, with triangular or shark skin shape vortex generators were obtained from wind tunnel tests. For the airfoil with shark skin shape vortex generator, its performance was compared with the results from computational fluid dynamics simulation. For all tests and simulations, the location of vortex generators was maintained at the 50% of chord length. The Reynolds number was maintained at 2.5 × 105. The only varied parameter other than the shape of vortex generator was the angle of attack which was varied between 0° and 20°, with 2° increment. In some conditions, the performance of airfoil with shark skin shape vortex generator was better than the airfoil with triangular vortex generator. The simulated lift and drag coefficients for airfoil with shark skin shape vortex generator are comparable with the results from experiments. These findings are important for future development of highly efficient airfoil with innovative shape of vortex generator.

Nur Faraihan Zulkefli, Mohamad Asmidzam Ahamat, Nurul Fatihah Mohd Safri, Nurhayati Mohd Nur, Azmin Syakrine Mohd Rafie

A Prototype Development and Evaluation of Electrochemical Device for Heavy Metal Measurement

Heavy metals are highly toxic, carcinogenic, and non-biodegradable and may cause harmful effects on human health and the environment. To reduce or eliminate heavy metal contamination, it is necessary to accurately determine the amount of heavy metal in the environment. Traditional detection techniques are expensive, bulky, and not suitable for in-site applications. The electrochemical technique using a potentiostat instrument is a reliable alternative as its potential to fabricate on a small circuit for in-site application. “Black boxes” nature of most commercial potentiostat leads to various development of lab-build potentiostat. Most lab-build potentiostat was designed for general purpose used. This paper focused on development and evaluation of potentiostat specific for heavy metal detection. The development consists of a readout circuit of electronic components together with NI myRIO-1900 as a controller system. Linearity and accuracy of the readout circuit were evaluated. Single and simultaneous detection of copper (Cu), cadmium (Cd) and lead (Pb) were tested. The results show that the proposed design has good repeatability comparable to a commercial potentiostat.

Siti Nur Hanisah Umar, Elmi Abu Bakar, Noorfazreena Mohammad Kamaruddin, Naoki Uchiyama

Analysis of Pressure Coefficient Around Three Airfoils Operating at Different Reynolds Number Using CFD and XFOIL

In this paper, CFD is used to perform analyses of 3 different airfoils at varied angles of attack. The objective is to determine a suitable CFD model and find a single validated simulation setting applicable for different airfoils. The pressure coefficient around an airfoil is analyzed. A single Reynolds number condition is assigned for testing of each airfoil over different angles of attack. The CFD results are compared with experimental and XFOIL data. The solver used is the commercially available ANSYS v16.0 CFX. From this study the following results are derived: It is found that the simulation results closely match experimental results at Reynolds number in the range of 3 million. At low Reynolds number, the CFD approach struggles to reach the higher values of pressure coefficient achieved experimentally. It is also found that XFOIL provided better results compared to CFD and also converged at a faster rate. The above results are discussed in this paper.

Aravind Seeni, Parvathy Rajendran

CFD Analysis of a Novel Propeller Design Operating at Low Reynolds Number

The aerodynamic performance of a propeller is characterized by the thrust produced, torque and efficiency. In this paper, novel blade shapes are tested using the technique Computational Fluid Dynamics (CFD). The blade shapes are based on a passive slotted design in which slots are present on the suction side i.e. on the upstream front side of the blade. Two slotted design models are tested using the commercial CFD solver ANSYS Fluent. The slotted designs are identical in terms of slot geometry (0.1 mm width, 0.2 mm depth) but differ in the location of slot along chord from leading edge (0.206c and 0.382c). In order to test the modified designs, a validation study of the baseline model of a propeller is conducted. Then slotted designs comprising two models are tested and compared to baseline design. The propeller model considered is the APC10x7 Slow Flyer and the Reynolds number of flow analyzed is approximately 68,500 (estimated at 75% radial distance) The results showed that the presence of slots have altered the performance. The presence of slots has reduced the thrust performance for the entire operational range of advance ratios. However, the power performance has increased due to decrease in torque or rotational resistance of the propeller. The efficiency is thereby increased for one model for a specific range of advance ratios. In the case of another model, for most advance ratios the efficiency was found to be decreased.

Aravind Seeni, Parvathy Rajendran

Anisotropic Median Bilateral Filtering

In this study, a new image filter—Anisotropic Median Bilateral filter (AM-Bilateral) is proposed for image noise reduction. Unlike the Bilateral filter, AM-Bilateral filter is an iterative non-linear filter and decreases image noise continuously in every iteration. Performance evaluation of AM-Bilateral filter is done and compared with Bilateral filter, Median filter and Arithmetic Mean filter using various images with Gaussian noise. The simulation results have shown that AM-Bilateral filter outperforms other filters with higher Peak Signal to Noise Ratio (PSNR) and Structural Similarity (SSIM) on average.

Kai Yit Kok, Parvathy Rajendran

Aircraft Wing Aerodynamic Efficiency Improvement Using Longitudinal Spanwise Grooves

Passive flow control techniques are the advanced boundary surface modifiers to improve the aerodynamic performance by keeping the flow attached. The overall aim of this study is to implement semi-circular grooves over the NACA 2412 wing at various orientations, to keep the flow attached along with the relative aerodynamic performance changes of baseline and groove wing. Numerically simulation over a Low Aspect Ratio wing of order 1 with variant angle of attack, at an operating velocity of 30 m/s, and Re of 4.4 × 105 is presented. Grooves over a baseline wing disturb the flow behavior, thereby creates turbulence by producing rotating small eddies. These rotating vortices keep the flow attached for longer time by re-attaching the separated flow with enhancement in L/D characteristics. Variant of longitudinal grooves has been employed over the wingspan at different x/c location (1) near leading edge (0.2C), (2) near trailing edge (0.8C), (3) mid-span (0.5C), (4) triplet location (0.2C, 0.5C, 0.8C). The models are designed using CATIA V5R20, and ANSYS Fluent helps to simulate the flow behavior, vortex development and aerodynamic performance difference between models. From the simulation study, it is clearly understood; the baseline wing shows massive boundary flow separation on the suction side of the wing beyond 14° AOA with immediate stalling. The presence of these longitudinal grooves enhances the stalling characteristics by keeping the flow attached up to 18° AOA. In all the optimized wing models, the L/D shows at least 0.05% improvement compared to baseline wing. However, the aerodynamic characteristics show pronounced results in the case of the triplet groove wing. It proves that creating roughness over smooth wing shifts the stalling angle and also improves the lift in that region with minor turbulence drag reduction.

Samuel Merryisha, Parvathy Rajendran

Generalized Eshelby Integral Formula for Multiple Inclusion Composite Materials

Eshelby integral formula, which was initially derived for a single inclusion embedded in all matrix system, plays a fundamental role in the micromechanics of composite or heterogeneous materials. The integral formula is remarked to be readily generalized to the case of multiple inclusions. However, the proof for such case has never been established. Herein, the integral formula is reformulated within the frameworks of generalized self-consistent method for the case of multiple inclusion composite system and thus, establishing the proof of its generalized version.

Abdul Rauf Abdul Raif, Muhammed Fadzli Ismail, Mulia Minhat

Applicability of Rule of Mixtures to Estimate Effective Properties of Nanocomposite Materials

A rule of mixtures is employed and modified to examine the effective elastic properties of a unidirectional composite lamina reinforced with nanostructure-hybrid fibers. Such fiber system is designated when nanostructure such as nanowires or carbon nanotubes are radially grown on the surface of primary fiber. When combines with matrix, a complex three-phase composite with enhanced elastic properties is expected. Herein, the applicability of this simple micromechanics method to reliably estimate the effective properties of such advanced novel composite material is assessed. The results demonstrated that the method is capable of modeling the effects on elastic properties of a composite due to the presence of nanostructure. However, in light of published experimental data and other micromechanics results, the proposed method is found to be at best, applicable for a composite that has a very low fiber volume fraction only except when an axial Young’ modulus is predicted.

Muhammad Lutfi Mat Rodzi, Muhammed Fadzli Ismail, Mulia Minhat

Flow Field Measurement of Wake Generated by Gourami Fish Tail

Application of biomimetic systems has been an advancement in the robotic field. The development of underwater robot imitates the locomotion and flow around a swimming fish since its manoeuvrability and efficiency is excellent. The work presented in this manuscript aimed to visualize the flow of a real fishtail to aid the design and fabrication of a mechanical fishtail. The flow across the tail of a Gourami fish when it was visualized and observed in a water channel under static water condition. The tail kinematics of the real fish were extracted and applied on the designed mechanical fishtail. The designed mechanical fishtail was employed to undergo the flow visualization experiment using Particle Image Velocimetry (PIV). The experiment was conducted with the flow in the water channel set at a velocity of 0.2 m/s while the mechanical fishtail was set to flap with an amplitude of 20°. Measurements were repeated with the tail flapping amplitude of 40°. Chain of vortices was observed to be generated by both real fishtail and mechanical fishtail. Through comparison, it is noticed that the flow pattern generated by the mechanical fishtail flapping with the amplitude of 20° has the highest similarity with the actual Gourami fish compare to the flapping amplitude of 40°.

Lai Hoong Chuin, Soh Ling Xin, N. A. Razak, Zarina Itam, A. F. Osrin

Design Factors of a Plasma Reactor with a Swirling Flow Field for Production of Rutile TiO2 Nanoparticles

This study presents the development of a plasma reactor producing rutile TiO2 nanoparticles as a white pigment. The effects of reactor design factors are also considered based on experimental data. A Direct current thermal plasma using Ar as the plasma medium was applied to heat the reactor. TiCl4 and O2 were the reactants with TiO2 and Cl2 as the products. The advantage of this process is the production of titanium dioxide nanoparticles without the co-generation of HCl. The effects of design factors such as the position of the nozzles supplying the reactants, temperatures of the reactor and heater, residence time, and swirl number of the flow field on rutile phase generation were investigated. The collected titanium dioxide nanoparticles were examined using X-ray diffraction (XRD) and Scanning electron microscope (SEM). Although there was no significant effect of nozzle position, the temperatures of the reactor and heater showed strong correlations with the rutile phase contents, with temperatures of 1030 to 1060 °C for the reactor and 750 °C for the heater yielding the maximum rutile content of 79.8% at a residence time of 2.2 s. The gas flow pattern in the furnace also exhibited an effect on rutile content, i.e., as the swirl number in the reactor increased, the rutile phase content in the TiO2 also increased. From experimental results and Computational fluid dynamics, the optimum swirl number was estimated to be between 0.7 and 0.8.

Byeongjun Jeon, Junghun Shin, Donghoon Shin

Development of a Flameless Furnace with Swirling Reversed Air Injection Method

We developed a new flameless combustion called swirling-RAI (reversed air injection) and evaluated through experiments and numerical simulation. In a circular furnace which has a specific purpose to heat pellet bed, two pair of nozzle sets from the concept of RAI are installed in the inversed direction against each other. Due to the high momentum of angled air nozzles installed axisymmetric, the overall flow in the furnace is swirling. The experiments showed methane-air combustion without flame and NOx emission was 3 ppm while CO was not detected at the exit. The numerical simulation showed detail of flow and reaction in the S-RAI furnace to understand its phenomena. The experimental and simulation results are also compared to see the reliability of the simulation. The complexity of flameless combustion makes the proper simulation difficult. In particularly, oxygen concentration at Port 2 showed a difference. However, the simulation gives enough information of flow field and insight of its effect on the flameless combustion, which shows two recirculating flow patterns in the furnace; the first recirculation is occurring at the top due to the ejection effect of nozzle jets, and the second recirculation is located at the reducing cone under the nozzles which is due to swirling flow.

Namgyun Oh, Jaesam Shin, Byeongjun Jeon, Chonggun Choi, Donghoon Shin

Study on the Toluene Removal Characteristics of Glass Fiber Filter Coated by TiO2 Photocatalyst

This study analyzed the mechanism of photocatalytic reaction and described the toluene removal process through the equation of L-H reaction rate. Experiments were conducted by using the designed photocatalytic reactor to measure UV radiation, differential pressure in filter and the toluene removal efficiency as a function of air humidity, air velocity, toluene concentration of the reactor entrance and UV radiation. The computational analysis was performed to simulate the UV radiation on the filter surface, the flow field in the reactor and the toluene removal. As a result of the experiments, it was confirmed that the humidity had a large effect on the photocatalytic reaction efficiency. While the amount of the toluene removal increased, the toluene removal efficiency decreased in case of increasing the toluene concentration of the reactor entrance. The maximum and minimum toluene removal efficiency was at 28% and 3.1%, respectively. As a result of computational analysis, the uniformity of UV radiation on the filter surface was at 87%, and it was confirmed that the air flow in the reactor was uniform, and the L-H reaction model was considered as appropriate model for the photocatalytic reaction in this study.

Fengyun Li, Jie Sun, Donghoon Shin

Lift and Drag Trend of Exocoetus Volitans Model in the Wind Tunnel

Flying fish is a fascinating animal that has the abilities to swim and glide. These unique abilities have attracted interest amongst scientist and researchers alike. Several studies have been performed to better understand flying fish aerial locomotion and aerodynamics performance. However, understanding biological beings’ aerodynamics characteristics such as flying fish have always been more than educated estimation. Researchers have approximated the physics of flying fish based on known aerodynamics principle of other flying animals with similarly aerodynamics parameters. In the present study, we manufactured and tested a model of Exocoetus Volitans flying fish in the wind tunnel. The experiment evaluated the lift and drag coefficients generated by Exocoetus Volitans wings by subtracting the aerodynamics forces contribution from other fish parts. The experiment evaluated the performance at various angles of attacks starting from −15° to +45° and airspeeds ranging from 10 to 15 m/s. The results show that as the angle of attack increases, the lift and drag coefficients also increase even beyond 20°. The maximum lift coefficient is achieved when the angle of attack is at 40°.

A. F. Osrin, N. A. Razak, Aizat Abbas, Zarina Itam

Flatwise Compression and Buckling Characterizations of Adhesive-Free Additively Manufactured Defected Architected Structures

In the light of its versatility, the additive manufacturing technology is shaping up to be a boon for the fabrication of advanced structures. As demands soar for the accelerated adoption of this emerging technology, understanding the mechanics of parts derived from the process is crucial to reaping its full potential. In this study, six different unit cells are used to build up different architected structures with artificially introduced missing unit cells. The six structures are screened using the finite element analysis after which focus is restricted to two, which are then produced via the fused filament fabrication method. Assessments of the compressive resistance of the architected structures are conducted. Results indicate a considerable gradual deterioration of the buckling and compressive resistance with an increasing number of missing cells. At higher compressive loads, rupture of unit cells, cracks, minor wrinkling and tearing of the architected structures were observed.

Khameel B. Mustapha, Mohammad Saad, Yousif A. Abakr

Technical and Economic Viability Assessment of Different Photovoltaic Grid-Connected Systems in Jordan

In this work, the technical and economical evaluation of the application of different Photovoltaic (PV) on grid systems was studied based on experimental results and theoretical models. Six types of 20 kWp PV grid-connected systems working at Applied Science Private University, Jordan were involved in study. The Six types of different PV systems studied were: Poly-Crystalline South directed (Poly S), Mono-Crystalline South directed (Mono S), Mono-Crystalline East West directed (Mono EW), Poly-Crystalline East West directed (Poly EW), Thin-Film directed to the south, and a Concentrated PV type with automatic two axes tracking (Con Tracker). For the 20-kWp grid connected systems, the yearly production, the yearly savings, the initial investment costs and the Operating & Maintenance (O&M) costs were estimated, evaluated and compared to get the most beneficial investments by using different economical methods. Con Tracker system presented the most feasible system with higher Net Present Value (NPV) (71733.06 JD), Internal Rate of Return (IRR) (45%), and short Payback Period (PBP) (3 years) than those values of Thin-Film with NPV (42638.15 JD), IRR (37%) and PBP (3 years), Poly S with NPV (44887.23 JD), IRR (34%) and PBP (3 years), Mono S with NPV (48267.89 JD), IRR (33%) and PBP (3 years), Mono EW with NPV (40998.52 JD), IRR (29%) and PBP (4 years), finally Poly EW with NPV (35793.14), IRR (28%) and PBP (4 years).

Salah Abdallah, Dana Salameh

Aircraft Arrival Delay Under Uncertainty: G-Queue Modelling Concept

In response to tremendous growth of air traffic, achieving demand-capacity balance by ensuring airport runway’s adequacy and maximizing airport efficiency is extremely crucial. It is of utmost important especially to the airport operators in tackling flights delay under uncertainty. As such, this paper aims to propose a modeling framework for aircraft arrival delay, in the form of a G-queue (i.e. a queuing system with negative arrivals). In particular, this paper highlights that inbound flight delay can be modeled as a generalized G-queue network, by presenting a schematic structure to model aircraft arrival delay (with G-queue concept). Besides, a four-step framework is discussed to obtain numerous key data inputs for model development. In addition, a novel approach, namely K-GLE, is addressed accordingly in order to capture general distribution of interarrival and service time. Concisely, this paper supports the beneficial application of G-queue in modelling aircraft arrival delay. It is anticipated that the proposed methodology would be useful to assist the airport operators to improve on-time performance when dealing with arrival throughput under uncertainty (including stochastic demand).

Lay Eng Teoh

Evaluation of Combustion Characteristics on Simple Cylindrical Combustion Chamber for Different Operating Conditions and Alternative Fuels

This study investigates the influence of different operating conditions including fuel temperature, droplet sizes, fuel injector and type of fuel on combustion characteristics of a simple cylindrical combustion chamber. Alternative fuels namely Jatropha Bio-synthetic Paraffinic Kerosene (JSPK), Camelina Bio-synthetic Paraffinic Kerosene (CSPK), mixture of 50% JSPK with 50% Jet-A (50JSPK/50Jet-A) and mixture of 50% CSPK with Jet-A (50CSPK/50Jet-A) are used while Jet-A is used as baseline fuel. At every cases, droplet sizes are varied at 20–40 µm, fuel temperatures are varied from 300 to 500 K and the spray half cone angles are varied from 30° to 50°. Results obtained show that smaller droplet size will lead to high combustion rate and thus provide better efficiency whereas higher fuel temperature produced better evaporation in the chamber. At higher spray half cone angle, shortest penetration length is produced and took shortest time for droplets to reduce its diameter. Among the four tested fuels, 50JSPK/50Jet-A and 50CSPK/50Jet-A have the shortest time to evaporate which indicated that both fuel mixtures have higher evaporation rate due to lower boiling point and density.

Sim Sing Mei, Nurul Musfirah Mazlan

Design and Development of Renewable Energy Water Pump

This study aims to develop a water pump that utilizes natural hydro energy as driving force to deliver water to a higher ground. The conceptual design of using water wheel to extract kinetic energy from water flow, and transfer the energy to power multiple piston pump was created based on the extensive literature review findings. The actual prototype is then built and modified to suit the actual environment considerations. Findings show that single pump is able to produce maximum pressure head of 7.14 m and the maximum volume flowrate achieved is 19.2 l/h (320 ml/min). However, when multiple piston is connected in series (in this research three pistons is used), the maximum water head increased to 13.77 m and the maximum volume flowrate about 19.2 l/h. This result shows that the water pump can be used in remote area or places at higher ground that does not have constant water access. Performance of the whole system can be improved by several factors such as adding more blades to the water wheel, steeper angle and better piston shaft design for water pump, and also proper water sealing of the whole system to prevent head loss and increase the overall performance.

Man Djun Lee, Pui San Lee, Jasper Ling, Heng Jong Ngu

CAD-Based 3D Grain Burnback Analysis for Solid Rocket Motors

Propellant grain burnback analysis is crucial for solid rocket motor design and performance prediction. Unlike 2D grain configurations, 3D configurations are complex, hence, simulating their burnback inside the rocket combustion chamber is a tedious and time-consuming process. This study proposes a fast and simple approach for modeling, and evaluating the burning area of 3D propellant grains, based on particular features available in a commercial CAD software. A common 3D Finocyl grain configuration available in the literature has been taken as a test case. The results obtained from the proposed approach were compared with the published experimental data and showed good agreement. The proposed approach can handle any arbitrary complex grain geometry and provide fast and reliable analysis for the preliminary design stage of solid propellant rocket motors.

Ahmed Mahjub, Qummare Azam, M. Z. Abdullah, Nurul Musfirah Mazlan

Numerical Simulation of Suddenly Expanded Flow from Converging Nozzle at Sonic Mach Number

Low pressure created at the blunt base results in a substantial increase in the base drag. Controlling the base drag is required by regulating the base pressure. This study presents a turbulent numerical analysis of suddenly expanded flow in a 22 mm suddenly expanded duct with a converging nozzle which operates at sonic Mach number. A rib is placed circumferentially along the inner duct diameter. The rib is located at a different position of diameter duct namely 1D, 2D, 3D, and 4D. The height of the rib is increased from 1 to 4 mm, and the width is maintained at 3 mm throughout the study. The nozzle pressure ratio of the flow is ranging from 1.5 to 5. The numerical analysis carried out is also compared with the duct without rib. The results obtained reveal that the rib changed the flow field and causes variations in base pressure. The rib at the 2D location is found to be the base pressure controller at a moderate level. While 1D reduces the pressure, but the ribs placed at 3D/4D results in a significant increase in the base pressure level for all nozzle pressure ratios of the present study. The pressure variations and velocity field are also studied using simulation results, and they show that these parameters are influenced mainly with the use of rib of a particular location and the height of the rib.

Ambareen Khan, Mohd Azmi Ismail, Nurul Musfirah Mazlan

Computational Analysis of a Multi-orifice Rotary Injector with Air Core

The present computation study investigates multi-orifice injection with centre air core. To enhance the mixing process, high pressurized air has been injected at the centre portion of the orifice plate. Numerical simulation has been carried out to study the gaseous jet interaction and liquid jet interaction with air with toluene-air, kerosene-air and water-air as working fluids. Species transport model and Volume of Fluid (VOF) method in Multiphase model are used in the present analysis, which is capable of predicting the interface between these two different fluids each of which is having different mass densities. Initially, dimension of computational domain has been optimized by simulating jet through multi-orifice injector into mixing chamber of different dimensions. Later, grid independent study has been carried out with an optimum computational domain for five different grid sizes. Performance parameters like maximum penetration and volume fraction of liquid profile at different downstream locations has been compared in these five different cases. And one particular grid size is chosen with reasonable computational cost for the rest of analysis. Steady and transient simulations were performed to study the interaction between jet and air. Effect of centre air core on penetration length has been studied and compared. Deformation of cylindrical jet has been captured at different downstream locations and compared in steady analysis. Temporal evolution of the liquid jet forming the spray has been captured at different time-steps and compared in transient analysis.

S. Sahaya Jisha, S. Thanigaiarasu

An Experimental Study of Nozzle Geometry Effect on Mixing Characteristics of Two Different Twin Jets

This experimental work investigates the effect of circular nozzle with non-circular nozzle in a flow-field issuing from circle-ellipse twin jet and the same is compared with circular twin jet for Mach numbers 0.4 and 0.6. For the two twin jet cases, the jets emanated from both nozzles of the twin jets are free jets and had the identical Mach number. In both twin jet cases, for all the Mach numbers, the nozzle spacing (S) is 20 mm. The exit area is 78.5 mm2 which is same for all the nozzles. The ratio of nozzle spacing to nozzle exit diameter (S/D) for both cases was kept as 2. The results from the radial (Y) direction and shadowgraph pictures indicate that the circle-ellipse twin jet show better mixing enhancement as the entrainment between the ambient fluid and the jets from the nozzles is more. It is also observed that both the nozzle exit Mach number and nozzle geometry strongly influences the mixing of the two jets.

S. Thanigaiarasu, A. Muthuram, S. B. Jabez Richards, T. Vijaya Raj, Surendra Kumar Yadav

Effect of Alumina Nanofiller on the Mechanical Properties of 2D Woven Biotex Flax/PLA Fiber-Reinforced Nanocomposite

Fiber-reinforced polymer (FRP) composite has become one of the most important applications in the aerospace industry. More than 50% of the streamlined fuselage is made of composite material, and this will continue further due to technological advancement in the field of fiber-reinforced polymer composite material. Natural fiber (Bast, Stem, Leaf) are the most focusing in today’s era due to their environment-friendly nature. The development of 2D woven Biotex flax/PLA fiber-reinforced polymer composite integrated with alumina nano-filler is the main objective of the current study. This study mainly discussed the effect of alumina nanofiller using four concentrations from 0 to 3 wt% on the tensile and impact properties of sodium hydroxide treated and untreated biotex flax/PLA fiber-reinforced composite. The results exhibit that the increase in filler loading has improved tensile and impact properties. At 2 wt% filler loading, the tensile strength and impact strength was maximum. Further, increase the filler contents have adverse effects on mechanical properties. The results have witnessed better mechanical properties of treated compared to untreated reinforcement.

Adnan Amjad, Habib Awais, Muhammad Zeshan Ali, M. Shukur Zainol Abidin, A. Anjang

Investigating Dielectric Properties in Hybrid PLA-PHA Composites with Sodium Hydroxide Treated Flax Fibers

Dielectric materials with high permittivity and low dielectric loss are preferred for increasing insulation. Compared with metals or ceramics, polymer composites have proven to be good alternatives due to their exemplary material properties such as flexibility, machinability and adjustable dielectric properties. Besides, it is important to develop a novel material that has greater dielectric properties and one that uses sustainable materials in order to satisfy the growing field of green engineering. In this research paper, the dielectric constants, and dielectric losses are investigated to find the right composition of PLA-PHA blended, surface treated flax fiber infused biopolymer composites. Also, the factors that affect these properties such as interfacial polarization, dipole polarization have been explained according to the results obtained. The results obtained showed an increased dielectric constants and decreased dielectric loss at certain frequencies due to the inclusion of conductive copper fillers, surface treated flax fibers and a biopolymer mixture.

Elammaran Jayamani, Hari Prashanth Palani Velayuda Shannmugasundram, KokHeng Soon

Fabrication and Characterization of Lightweight Engineered Polypropylene Composites Using Silica Particles and Flax Woven Comingled Structure

The focus of the current study was the fabrication of woven comingled fabrics using flax and polypropylene yarns to improve the impregnation of flax reinforcing yarn in the polypropylene matrix. Hollow glass microspheres (HGM) as fillers were incorporated to tailor the mechanical properties of the resultant comingled composites. The dip and dry method was used to deposit the HGM on these comingled fabrics to achieve uniform distribution of hollow silica particles. Cross-ply composites were fabricated by these comingled fabrics using compression moulding technique. The mechanical properties were measured in terms of tensile, flexural and impact strength. Furthermore, the effect of HGM loading (1.5 and 3%) on mechanical properties was studied and compared with control composites prepared without HGM. It was observed that 1.5% inclusion of HGM had imparted an increase of 13.8 and 5.6% in the tensile strength and modulus respectively by enhancing the brittleness of the composites. However, a further increase in the HGM content from 1.5 to 3% had exhibited a decline of 10.2 and 8.8% in the tensile strength and modulus owing to the agglomeration of silica particles. A similar trend was observed in the flexural properties of the laminates. While, an increment of 10.4% and 18.2% was observed in the impact strength of the fabricated composite laminates by the loading of 1.5% and 3% HGM respectively.

Habib Awais, Yasir Nawab, Adnan Amjad, Aslina Anjang, M. Shukur Zainol Abidin

Numerical Study on the Effect of Innovative Vortex Generators in the Mixing Enhancement of Subsonic Jets

Numerical analysis of subsonic jets with and without tabs (vortex generators with exit area blockage of 4.84%) has been done in the present research paper. Two tabs has been fixed at nozzle exit diametrically opposite. ANSYS CFX software was used for analysis purpose and to understand the flow characteristics at four different Mach numbers 0.4, 0.6, 0.8 and 1.0. The main objective of the present study is to analyze the effect of innovative vortex generators in the form of solid tabs with triangular fins on either side offset to each other on the performance characteristics. Due to counter rotating streamwise vortices, there is large engulfment of masses from ambient air into the core jet, resulting in the reduction of potential core length.

S. Thanigaiarasu, S. B. Jabez Richards, V. Karthikeyan, A. Muthuram, Surendra Kumar Yadav, T. Vijaya Raj

Nonlinear Follower Force Analysis with Ground Static Test Validation of High Aspect Ratio Wing

This paper presents a technique proposed to analyzed the geometrical nonlinearity of High Aspect Ratio (HAR) wing at aspect ratio, AR 16 with the inclusion of follower force. In this study, nonlinear static analysis of HAR Wing model under non-follower and follower force was performed through the Finite Element Analysis (FEA) using MSC NASTRAN software. Two important parameters (force identification, ‘FORCE2’ and large displacement, ‘LGDISP’) are considered to demonstrate the FEA nonlinear static analysis of follower force. For validation, a ground static load test was performed using small-scale load application structure through a different load direction applied for non-follower and follower force. It was found that, the selection of LGDISP = 1 in FEA nonlinear static analysis of follower force shows closest results compared to experimental data. This exhibits that combination of large displacement and follower force stiffness in LGDISP = 1 contribute to the accuracy of nonlinear follower force results. Another finding shows that, techniques of determining the load direction in ground static load test is adequately to predict the tip deflection of HAR wing with a minimal percentage error obtained. The comparison for the load case under non-follower and follower force are also demonstrated through FEA and experimental. The results show that the follower force effect indicates a higher deflection than non-follower force for both considered cases; simulation and experimental.

Norzaima Nordin, Noor Shazwani Muhamad Rafi, Mohammad Yazdi Harmin

Effects of Circular Tabs on Enhancement of Jet Mixing

The Flow measurements were made in the circular jets using two tabs at nozzle exit, placed diametrically opposite locations. The total pressure was measured along the jet axis (X-Axis) and normal to the jet axis (Y-Axis) at Mach number 0.2. Also, total pressure was measured for free jet to compare the results. The effectiveness of circular solid tabs and circular tabs with hole to enhance the mixing of axi-symmetric subsonic jets has been presented in this paper. It is found that both the circular solid tabs and circular tabs with hole significantly enhance the mixing of jets. The potential core length were reduced by 37.5% and 62.5% for jet of circular tab with hole and solid tabbed jet compared to free jet respectively.

S. Thanigaiarasu, Surendra Kumar Yadav, S. B. Jabez Richards, A. Muthuram, T. Vijay Raj

Analysis of the Impact of Degradation on Gas Turbine Performance Using the Support Vector Machine (SVM) Method

Degradation is an important aspect in the operation and maintenance of gas turbines since it affects maintenance costs substantially. Hence, the study of degradation in terms of recoverable and non-recoverable degradation is crucial to formulate a correct maintenance strategy and, as a result, achieve optimum maintenance cost. In this paper, the impact of recoverable and non-recoverable degradation towards compressor discharge pressure, fuel gas flow, and exhaust gas temperature are measured during the start of run period that reflects the time period from the new gas turbine condition to the first scheduled offline crank wash, which normally approximates to 8000 running hours. For the study, a three-unit single speed light industrial gas turbine that drives an electrical generator to power up an offshore platform located in a tropical climate is considered. The measurement of the parameters has been conducted using the support vector machine (SVM) method.

Khairul Fata B. Ahmad Asnawi, Tamiru Alemu Lemma

Fast and Efficient Collision Avoidance Algorithm for Autonomous Mobile Robot

An autonomous mobile robot or Unmanned Ground Vehicle (UGV) is a vehicle that operates remotely, without human on-board. UGVs are widely used for mission-based applications that are often hazardous or/and inconvenient for humankind regardless of its sizes. As to enable its autonomous capability, UGVs often equipped with artificial eyes e.g. sensors and on-board camera to assist navigation during mission. In this experiment, we utilized a sweeping technique using ultrasonic sensor (HC-SR04) as the ‘eye’ of the mobile robot to map the obstacle around it using distance measurement. Meanwhile, an Arduino based controller is used to execute the avoidance algorithm. The ultrasonic sensor is programmed to sweep at six different angles to cover about 150° field of views. Path planning algorithm in this project provides the decision to avoid the obstacle and create temporary new waypoints within split seconds using decision table. We observed that the algorithm that uses decimal method is easy to implement and provides faster decision as compared to the binary method.

A. F. Hawary, A. N. Azizan

Experimental Investigation of Mixing Enhancement Through Nozzle Exit Modification in Subsonic Flow

There is a need of increase in efficiency and reduction of sound in jet engine where the researchers found that if mixing enhancement is made possible at the area prior to the primary zone of the combustion chamber the efficiency could be increased. As the free jet out of the nozzle taken the time to decay, there is a possibility for the fuel to exit at high speed in an unburnt state which primarily tends to reduce the efficiency of the jet engine. To overcome this problem, a square shaped fin tabs were designed and fabricated and the same was fixed diametrically opposite to the nozzle exit to create formation of vortices, thus the decay is made to be smaller and mixing of air and fuel will be enhanced. The experimental study was made along with data acquisition system to witness the effect of Mach number variation on and pressure ratio with respect to X/D as well as Mach number ratio by having a supply of air at M = 0.4, 0.6, and 0.8 in both the cases.

T. Vijayaraj, S. Thanigaiarasu, S. B. Jabez Richards, Surendra Kumar Yadav, A. Muthuram, S. Jaichandar, S. Jagadeshwaran

Experimental Modal Analysis of a Simple Rectangular Wing with Varying Rib’s Orientation

Three oriented rib profiles of a simple rectangular wing model were considered for the experimental modal analysis (EMA). They were namely the best individual, best parallel and best overall oriented rib profiles. The wing was setup as a cantilever-like condition with a roving hammer technique was employed for the testing. Modal properties with respect to natural frequency and mode shape were measured and the results were then compared against the baseline configuration. From the results, the impact towards the bending modes were found very minimal and can be negligible for all the considered oriented rib profiles. Nevertheless, significant increases in torsional frequencies was found for the best overall oriented rib profile when compared with the baseline configuration, showing that the wing becomes much stiffer in twisting direction without any increase in weight. Hence, this offer a possibility in flutter improvement or in weight reduction if the flutter performance to be kept similarly as the baseline configuration.

M. S. Othman, L. Teh, M. Y. Harmin

Validation of Rotor-Disc Model for Light Autogyro in Steady-State Flight Mode

Most rotorcraft flight dynamic studies employed higher fidelity rotor modelling approach to precisely resemble the dynamic behaviour of the real rotorcraft in simulation. However, high-fidelity calculations always implemented at the expense of other simulation costs, such as the CPU run-time and the machine hardware. This paper is aimed to highlight the used of lower fidelity rotorcraft calculation approach for light autogyros in normal flight mode where extensive calculations are less vital. A lower fidelity helicopter simulation package, named Helicopter Generic Simulation (HGS) is used as the basis where the structural features are modified according to the unique autogyro’s kinematics. Due to the common longitudinal stability issues previously experienced by typical light autogyros, validations are made in longitudinal steady-state flight mode against the real flight data of the test autogyro. Simulation results show tolerable steady-state predictions of important parameters, such as the fuselage pitch attitude and the longitudinal shaft tilt. Hence, it is recommended to employ the rotor-disc modelling approach for autogyro’s applications that are not subjected to complex rotor blade dynamics, such as in automatic flight control and inverse simulations in normal flight mode.

Shahrul Ahmad, Douglas Thomson

Adsorption Characteristic of a Two Layer Hollow Cylindrical Silica Bed

Desiccant air conditioning systems are using the concepts of desiccant dehumidification and evaporative cooling. Apart from desiccant material, the flow characteristics and inlet conditions also play vital role in improving the dehumidification performance of a desiccant bed. This paper communicates the experimental adsorption characteristics of two layer hollow cylinder silica bed that is used in desiccant-cooling systems for warm and very humid climates, during adsorption processes. Air velocity varied between 1 and 5 m/s and experimental investigation concluded that moisture adsorption ability is increased respect to air velocity for hollow desiccant arrangement. 3.7 m/s air velocity illustrated 2.2 times higher dehumidification rate than 1 m/s.

Pravinth Balthazar, Mohd Azmi Ismail, Lee Chern khai, Muhammad Iftishah Ramdan, Nurul Musfirah Mazlan, Hussin Bin Mamat

The Effect of Flow Control on Wing-In-Ground Craft Hull-Fuselage for Improved Aerodynamics Performance

Wing-In-Ground (WIG) crafts has become one of the latest technologies in the marine vehicle sector. Improvements on WIG craft to increase aerodynamic performance has been done for decades. However, WIG crafts must be able to overcome significant hydrodynamic drag take-off from water surface and aerodynamic drag during flight. The current design of the hull-fuselage can cause flow separation and increase in drag hence flow control devices can be used to improve flow separation phenomenon on the hull-fuselage of the WIG craft. The objective of this study is to investigate the effect of flow control on the aerodynamics performance of WIG craft through wind tunnel experiments. From the results, CD values were reduced with the presence of flow control on WIG hull-fuselage. Different configurations on height, angle, and spacing of the flow control device helped in obtaining minimum CD. The flow control device was proven to reduce CD for up to 25% from the baseline model. This indicates that flow control device is helpful in improving aerodynamics performance of WIG craft.

Irahasira Said, Mohd Rosdzimin Abdul Rahman, Azam Che Idris, Fadhilah Mohd Sakri, Mohd Rashdan Saad

Review of Hot Air Anti-icing System Inside Bias Acoustic Liner

Ice accumulation and noise dissipation in aircraft nacelle lip–skin are the two main issues faced by the aviation industry nowadays. In order to prevent ice formation and reduce engine noise at the same time, hot air anti-icing system has been incorporated into bias acoustic liner. This paper discusses briefly the introduction on aircraft crashes that happen due to icing issues, literature review on the types of hot air anti-icing systems and acoustic liners used today and its application in computational fluid dynamics as well as a summary on the advantages of bias acoustic liner in nacelle lip–skin.

Lee Chern Khai, Mohd Azmi Ismail, Yu Kok Hwa, Khairil Faizi bin Mustafa, Nurul Musfirah Mazlan, Pravinth Balthazar

Physical and Mechanical Characterization of Kenaf Fiber Filament Wound Composite Produced Using Vacuum-Bagging and Heat-Shrink Tube Method

Most natural fiber reinforcements in the industry are based on random discontinuous fibers. This study aims to demonstrate the potential of continuous natural fiber-reinforced composites in structural applications. Kenaf-cotton yarn composites have been manufactured by dry filament-winding process with winding angle that varies from 50 to 80° and wet lay-up assisted by two methods, i.e. vacuum-bagging and heat-shrink tube. A hoop tensile strength test was conducted and winding angle of 80o was found to give the highest tensile strength of approximately 49.3 MPa. Heat-shrink tube method improved composites performance by 36%.

Sharifah Fathin Adlina Syed Abdullah, Nurul Zuhairah Mahmud Zuhudi, Khairul Dahri Mohd Aris, Mohd Nazrul Roslan, Mohamad Dali Isa

Flow Visualization Study Using Dye Mixtures on a Hydrokinetic Turbine in a Water Tunnel

A simple gravity-feed dye injection system is developed in this study and used as a flow visualization technique for dye mixtures consisting of dye with water (DW) and dye with water and milk (DWM) with combination ratios of 1:9, 3:7 and 5:5 for DW; and 1:5:4, 3:3:4 and 5:1:4 for DWM. All dye mixtures are investigated under dynamic flow regimes at 0.085, 0.119 and 0.80 m/s water flow speed, respectively. The practicality of the mixtures is analysed in terms of dye clarity, rate of dispersion, and dye flow path to determine the best dye mixture for each flow regime. A hydrokinetic turbine model is placed in the test section of the water tunnel to study the flow structures across the model. At 0.085 m/s, the DW with 1:9 ratio is the best dye mixture provided the turbine is placed not more than 6 cm from the injector. At 0.119 m/s, DWM with a 3:3:4 ratio is the best solution, because milk prolongs the dye diffusion thus retaining the dye traces in the water, whereas at 0.80 m/s, the effect of milk in reducing the dye dispersion is more significant. A clear dye flow pattern can be observed when the dye concentration is increased; thus, DWM with the ratio of 5:1:4 is found to be the best dye mixture for that flow speed. A reliable flow visualization study can be achieved if a suitable dye mixture is used for a specific flow regime.

Teo Chen Lung, Mohd Badrul Salleh, Noorfazreena M. Kamaruddin

Backward Bent Duct Buoy (BBDB) of Wave Energy Converter: An Overview of BBDB Shapes

The energy extracted from ocean waves is one of the promising types of renewable energy to meet the energy demands. There are several projects conducted worldwide on various wave energy designs and one of them is floating oscillating water column (FOWC) type. The most investigated FOWC device currently is the backward bent duct buoy (BBDB) concept. However, the full potential of FOWC, is still not fully investigated and understood. Therefore, this paper presents an overview on most of the investigations previously conducted on FOWC. The optimised design parameter of FOWC in terms of main body corner shapes and buoyancy module shapes will be presented and suggested.

N. I. Ismail, M. J. Aiman, M. R. A. Rahman, M. R. Saad

Turbulence Intensity in Water Flow for Hydrokinetic Turbine Application

A water tunnel is used to investigate a hydrodynamic behavior of an immersed body in the fluid dynamics study. The operational principle of water tunnel is identical to a wind tunnel but with a different working fluid and higher flow-pumping capacity. Tests such as flow visualization in wind tunnel are more challenging, as turbulent flows in wind dissipate quickly whilst water tunnel is more suitable for such purpose due to its higher fluid viscosity. However, the turbulence in the water tunnel test section must be low in order to produce a valid result. The present work focuses to improve the previous water tunnel performance to mimic a river flow that has been developed for micro hydrokinetic application particularly to reduce the turbulence intensity and improve its flow uniformity. To achieve this objective, several primary components of the water tunnel were modified, fabricated and assembled. Quantitative measurement on the velocity profiles and uniformity of the water flow at the test section were analyzed with small increments of 2 cm between the measured points. This was performed by collecting the data of the velocity at every point in the cross-section with increment of 1 cm. The results obtained were then used to plot a uniformity graph and analyze the turbulence intensity in the water tunnel test section. The turbulence intensity in the water tunnel test section after modification produced a minimum result of 6.8% in comparison to the previous version around 9.7%. Thus, the turbulence intensity in the water tunnel was reduced by 29.9%

Viknaraj Subramaniam, Noorfazreena M. Kamaruddin

Statistical Overview of CubeSat Mission

The number of CubeSats launched since the first group of six CubeSats was launched in March 2003 has increased. Several reliable databases that collect CubeSat information show that 1035 CubeSats have been launched as of 31 December, 2018. The author has taken the opportunity to use the information published in these databases and presents a statistical overview of CubeSat missions in this paper. This overview will hopefully be beneficial to the readers.

N. M. Suhadis

A Physical Characterisation for the Preliminary Fabrication of Natural Woven Fabric Prepreg and Their Composites

In order to find alternative composite material that possesses the ability for a great revival of structural application, cheap and environmentally friendly, natural woven fabric prepreg have earned its place as a replacement to traditional synthetic fabric prepreg. However, the limitation is the applicability of techniques of fabrication, which are compatible with the different properties of natural woven fabrics. The investigation on the individual material of natural woven fabric and resin are also essential to recognise the factor that influences the fabrication process of prepreg product. A preliminary experiment conducted on three different types of natural woven fabric, i.e., flax, bamboo, and jute in the form of a single-layer prepreg product which combined with Acrodur polyester resin. The resin content and their dispersion, prepreg, fibre and resin area weight are the parameters evaluated. The produced natural woven fabric prepregs have retained the resin content more than 50% (55.7–63.6%) for jute and flax, but only 47.6% resin content for bamboo material.

Fadzil Adly Ishak, Wan Muhammad Izzat Wan Zaludin, Nurul Zuhairah Mahmud Zuhudi, Khairul Dahri Mohd Aris

Vibration Signal Separation Technique by Using the Combination of Adaptive Filter and Hilbert Transform for Defect Machine Component in Rotating Machinery

This paper focused on enhancement defect signal by separating the unwanted signal by using combination of Adaptive Filter and Hilbert Transform. This combination is performed via simulation as well in experimental work. A growth index is introduced to serve as indicator to verify the fault detection capability. The result of this combination is compared with previous approach which are combination between wavelet packet and Hilbert Transform. The results showed that the unwanted signal is successfully separated, and sign of failures is greatly enhanced.

K. A. Wahid, M. N. F. Saniman, M. A. Khairul, I. A. Azid

Experimental Assessment of Nonlinear Modal Behaviour of Flexible Beam

Nonlinearity is a frequent occurrence in engineering structures. The nonlinearity detection in the operating mechanical systems is important because the nonlinearity can change the dynamic behaviour. The aim of this work is to experimentally measure the nonlinearity of a flexible beam structure due to the different applied dynamic load configurations. In this study, the modal parameters were obtained from the modal testing. The excitation approach by adopted the burst random excitation through an electromagnetic shaker and the vibration response was measured using accelerometers. The frequency response function (FRF) at different level of dynamic excitation was utilized to exhibits the nonlinear behaviour. The elastic vibration characteristics which are bending and torsional modes were compared to identify the nonlinear. As a conclusion, the results showed that the nonlinear property of the flexible beam is due to the geometric nonlinearity.

A. R. Bahari, M. A. Yunus, M. N. Abdul Rani, W. I. I. Wan Iskandar Mirza, M. Z. Nuawi
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