Gas Turbine Design, Components and System Design Integration

Frontmatter

Chapter 1. Introduction, Gas Turbines, Applications, Types

Abstract

Gas turbines are engines within which the chemical energy of the fuel is converted either into mechanical energy in terms of shaft power or into kinetic energy. Gas turbines that produce shaft power are power generation gas turbines. Gas turbines that convert the fuel energy into kinetic energy are used for generation of thrust to propel an aircraft.

Meinhard T. Schobeiri

Chapter 2. Gas Turbine Thermodynamic Process

Abstract

The first step toward designing a new gas turbine is to generate its thermodynamic cycle diagram. This diagram provides the essential information about the connection between the turbine inlet temperature TIT, the compressor pressure ratio \( \pi_{c} \) and the gas turbine thermal efficiency \( \eta_{th} \). Starting with a simple GT-cycles, in the following sections methods are introduced to determine the GT-efficiency and its improvement by changing the gas turbine configurations and cycles.

Meinhard T. Schobeiri

Chapter 3. Thermo-Fluid Essentials for Gas Turbine Design

Abstract

As seen in the previous chapters, gas turbines consist of many components within which a chain of conversion of energy takes place. Design of a modern gas turbine engine with its components requires solid knowledge of aero-thermodynamic, heat transfer, combustion and solid mechanics design of these components. Aerothermodynamics is the very basic tool for design, off-design and dynamic calculations of gas turbine components and hence the gas turbine system.

Meinhard T. Schobeiri

Chapter 4. Theory of Turbomachinery Stages

Abstract

The energy transfer in turbomachinery is established by means of the stages. A turbomachinery stage comprises a row of fixed, guide vanes called stator blades, and a row of rotating blades termed rotor. To elevate the total pressure of a working fluid, compressor stages are used that partially converts the mechanical energy into potential energy.

Meinhard T. Schobeiri

Chapter 5. Turbine and Compressor Cascade Flow Forces

Abstract

The last chapter was dedicated to the energy transfer within turbomachinery stages. The stage mechanical energy production or consumption in turbines and compressors were treated from a unified point of view by introducing a set of dimensionless parameters. As shown in Chapter 4, the mechanical energy, and therefore the stage power, is the result of the scalar product between the moment of momentum acting on the rotor and the angular velocity.

Meinhard T. Schobeiri

Chapter 6. Losses in Turbine and Compressor Cascades

Abstract

The flow through a turbomachine is generally three-dimensional, viscous, highly unsteady, transitional, turbulent, and compressible. This complex flow is associated with total pressure losses caused by different flow and geometry parameters. To accurately predict the efficiency of a turbomachine, accurate flow calculation is required.

Meinhard T. Schobeiri

Chapter 7. Efficiency of Multi-Stage Turbomachines

Abstract

In Chapter 6, we derived the equations for calculation of different losses that occur within a stage of a turbomachine. As shown, the sum of those losses determines the stage efficiency which shows the capability of energy conversion within the stage. The stage efficiency, however, is not fully identical with the efficiency of the entire turbomachine.

Meinhard T. Schobeiri

Chapter 8. Incidence and Deviation

Abstract

Up to this point, the relationships developed for a turbomachinery stage have been strictly correct for given velocity diagrams with known inlet and exit flow angles. We assumed that the flow is fully congruent with the blade profile. This assumption implies that the inlet and exit flow angles coincide with the camber angles at the leading and trailing edges.

Meinhard T. Schobeiri

Chapter 9. Blade Design

Abstract

Flow deflection in turbomachines is established by stator and rotor blades with prescribed geometry that includes inlet and exit camber angles, stagger angle, camberline, and thickness distribution. The blade geometry is adjusted to the stage velocity diagram which is designed for specific turbine or compressor flow applications. Simple blade design methods are available in the open literature (see References).

Meinhard T. Schobeiri

Chapter 10. Radial Equilibrium

Abstract

In Chapter 4, we briefly described a simple radial equilibrium condition necessary to determine the radial distribution of the stage parameters such as, ф, λ, r, α_i, and β_i. Assuming an axisymmetric flow with constant meridional velocity and total pressure distributions, we arrived at free vortex flow as a simple radial equilibrium condition with rv _u = Const. In practice, from an aerodynamics design point of view, a constant meridional velocity component or constant total pressure may not be desirable. As an example, consider the flow field close to the hub or tip of a stage where secondary flow vortices predominate.

Meinhard T. Schobeiri

Chapter 11. Nonlinear Dynamic Simulation of Turbomachinery Components and Systems

Abstract

The following chapters deal with the nonlinear transient simulation of turbomachinery systems. Power generation steam and gas turbine engines, combined cycle systems, aero gas turbine engines ranging from single spool engines to multispool high pressure core engines with an afterburner for supersonic flights, rocket propulsion systems and compression systems for transport of natural gas with a network of pipeline systems are a few examples of systems that heavily involve turbomachinery components.

Meinhard T. Schobeiri

Chapter 12. Generic Modeling of Turbomachinery Components and Systems

Abstract

A turbomachinery system such as a power generation gas turbine engine, a thrust generation aero- engine, rocket propulsion, or a small turbocharger, consist of several sub-systems that we call components ([1], [2], [3], [4]). Each component is an autonomous entity with a defined function within the system. Inlet nozzles, exit diffusers, combustion chambers, compressors, and turbines are a few component examples. A component may consist of several sub-components.

Meinhard T. Schobeiri

Chapter 13. Modeling of Inlet, Exhaust, and Pipe Systems

Abstract

This chapter deals with the numerical modeling of the components pertaining to group 1 discussed in section 13.1.1 The components pertaining to this category are the connecting pipes, inlet and exhaust systems, as shown in Fig. 13.1. The function of this group consists, among other things, of the transportation of mass flow, and of converting the kinetic energy into potential energy and vice versa.

Meinhard T. Schobeiri

Chapter 14. Modeling of Recuperators, Combustion Chambers, Afterburners

Abstract

This category of components includes recuperators, preheaters, regenerators, intercoolers, and aftercoolers, Fig. 14.1. Within these components the process of heat exchange occurs between the high and low temperature sides. The working principle of these components is the same ([1], [2], [3]). However, different working media are involved in the heat transfer process.

Meinhard T. Schobeiri

Chapter 15. Modeling the Compressor Component, Design and Off-Design

Abstract

As mentioned in Chapter 1, the function of a compressor is to increase the total pressure of the working fluid. According to the conservation law of energy, this total pressure increase requires external energy input, which must be added to the system in the form of mechanical energy. The compressor rotor blades exert forces on the working medium thereby increasing its total pressure. Based on efficiency and performance requirements, three types of compressor designs are applied. These are axial flow compressors, radial or centrifugal compressors, and mixed flow compressors.

Meinhard T. Schobeiri

Chapter 16. Turbine Aerodynamic Design and Off-design Performance

Abstract

The turbine component is the power generator in a gas turbine system. As briefly discussed in Chapter 12, within a turbine component, an exchange of mechanical energy (shaft work) with the surroundings takes place. In contrast to compressors, the total energy of the working medium is partially converted into shaft work, thus supplying necessary power to drive the compressor component, compensate for the bearing losses and provide the net power for driving the generator.

Meinhard T. Schobeiri

Chapter 17. Gas Turbine Design, Preliminary Considerations

Abstract

The objective of this chapter is to introduce novice engineers and students of turbomachinery design course to the fundamentals of gas turbine design.

Meinhard T. Schobeiri

Chapter 18. Simulation of Gas Turbine Engines, Design Off-Design and Dynamic Performance

Abstract

Continuous improvement of efficiency and performance of aircraft and power generation gas turbine systems during the past decades has led to engine designs that are subject to extreme load conditions. Despite the enormous progress in the development of materials, at the design point, the engine components operate near their aerodynamic, thermal, and mechanical stress limits. Under these circumstances, any adverse dynamic operation causes excessive aerodynamic, thermal, and subsequent mechanical stresses that may affect the engine safety and reliability, and, thus, the operability of the engine if adequate precautionary actions are not taken.

Meinhard T. Schobeiri