Application of coupled CFD-DEM simulation to separation process in combine harvester cleaning devices

verfasst von: Dipl.-Ing. Christian Korn

Verlag: Springer Berlin Heidelberg

Buchreihe : Fortschritte Naturstofftechnik

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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This book discusses the application of the coupled CFD-DEM approach for simulating the separation of grain and material other than grain in combine harvester cleaning devices. Based on a literature study, it describes the most important influencing factors and presents a database for particle parameterization. It investigates the separation process in two steps with differing levels of process abstraction. The first step involves numerical separation in a vertically oscillating box with airflow, and in the context of a sensitivity study, investigates the effect of selected material, contact and operating parameters on the target variables’ separation time and grain purity. In the second step, the numerical separation process was performed in a 200 mm wide segment of a combine harvester cleaning device. The numerical results were then compared with experimental investigations in order to confirm the method’s applicability.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

The objective of the present thesis is a contribution to the application of the coupled CFD-DEM approach (CFD – Computational Fluid Dynamics; DEM – Discrete Element Method) to the separation process in combine harvester cleaning devices. The evaluation of prediction accuracy of simulation with the use of available models is in the foreground. However, the numerical model will be extended by enhanced particle design and parameterization tailored to biogenic particles, in particular wheat.

Christian Korn

Chapter 2. State of the Art

Abstract

In Chapter 2 the combine cleaning device and the separation process of grain and material other than grain based on vibro-fluidization are introduced. The most important influencing factors, characteristic values to describe the separation success as well as the necessary data base for the particle parameterization are compiled. Different methods to simulate dispersed multiphase flows are introduced together with their opportunities, limitations and required computational resources. Published investigations of numerical methods applied to separation process in combine harvester cleaning devices are summarized and discussed. The large number of influencing factors, their interactions, the wide range of scatter of properties, which is typical for biogenic particles, and the resulting complexity of the separation process drive the need for a strategic approach in order to create a valid simulation model.

Christian Korn

Chapter 3. Approach and Method

Abstract

Chapter 3 summarizes the objectives of the dissertation based on the conclusions of the literature review and the knowledge gaps identified in Chapter 2. The strategic approach, which consists of two major steps, is described. Further, the applied numerical methods CFD and DEM are described and the governing equations are given.

Christian Korn

Chapter 4. Process Abstraction, Parameterization and Sensitivity

Abstract

In Chapter 4, the separation process is approximated on a high level. A downsized domain with a reduced ground surface area is used. The separation is carried out as a batch system with pure vertical mechanical oscillation and air flow, which enables to suppress horizontal transportation process and to isolate working mechanisms of vertical separation. The numerical tests contain particles for grain, chaff and short straw, designed and parameterized based on literature review. The downsized domain is used on the one hand to perform preliminary tests to find an appropriate standard configuration. On the other hand, the most influencing basic material and interphase parameters are identified in the context of a parameter sensitivity study. By the comparison to corresponding experimental tests, the general applicability of the numerical method and the need for further research are evaluated.

Christian Korn

Chapter 5. Numerical and Experimental Tests of Separation in a Combine Cleaning Device

Abstract

In Chapter 5 the complexity of the process is increased. Tests in a 200 mm wide segment of a typical cleaning device are carried out numerically and experimentally. Based on the findings of Chapter 4, the material other than grain (MOG) is exchanged. The composition of the mixture and the shape of the DEM-MOG particles are reworked in order to fit the behavior of chopped straw. Additionally the variation of particle size as well as a model to implement particle moisture is introduced. A second parameter study is performed, taking mainly process parameters like MOG feedrate, MOG composition, intensity of mechanical and pneumatic stimulation etc. into account. A lab test rig is designed and manufactured in order to perform corresponding experimental tests. The results are compared based on process characteristic values like the grain loss, relative grain separation along chaffer (separation curve) and pressure drop over material layer.

Christian Korn

Chapter 6. Summary, Conclusions and Outlook

Abstract

Based on the findings of the literature review, the separation process in a cleaning device of a combine harvester can be characterized as a dispersed multiphase flow, where locally dilute and dense regimes (\( \alpha_{p} \ge 10^{ - 3} \)) are present at the same time. Fluid forces are driving particle motion and separation of grain from MOG together with the mechanical stimulation and the gravity. In particular, the drag force is the dominating part of the fluid forces; pressure gradient force, buoyancy force, added mass force, Basset force, Saffman force and Magnus force are neglected.

Christian Korn

Backmatter

Titel: Application of coupled CFD-DEM simulation to separation process in combine harvester cleaning devices
verfasst von: Dipl.-Ing. Christian Korn
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-662-61638-3
Print ISBN: 978-3-662-61637-6
DOI: https://doi.org/10.1007/978-3-662-61638-3

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Über dieses Buch

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Chapter 2. State of the Art

Chapter 3. Approach and Method

Chapter 4. Process Abstraction, Parameterization and Sensitivity

Chapter 5. Numerical and Experimental Tests of Separation in a Combine Cleaning Device

Chapter 6. Summary, Conclusions and Outlook

Backmatter

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