The role of small hydropower is becoming increasingly important on a global level. Increasing energy demand and environmental awareness has further triggered research and development into sustainable low-cost technologies. In developing countries, particularly in rural areas, the possibility of local power generation could considerably improve living conditions. With this in mind, the development of a next generation low-head hydropower machines was subject of investigation in the EU-project HYLOW. Being part of the research lines of that project, this thesis presents a numerical modelling approach to improve the design of machines like water wheels for increased hydraulic efficiency. Nowadays, Computational Fluid Dynamics (CFD) enables numerical models to be quite accurate and incorporate physical complexities like free surfaces and rotating machines. The results of the CFD simulations carried out in this research show that a change in blade geometry can result in higher torque levels, thereby increasing performance. Numerical simulations also enabled to determine the optimal wheel-width to channel-width ratio and further improve performance by modifying the channel bed conditions upstream and downstream of the water wheel. With a power rating in the low kilowatt range, low-head hydropower machines like optimised water wheels seem to have a clear potential for small-scale energy generation, thereby contributing to achieving the Sustainable Development Goals by providing local energy solutions.
Chapter 1 Introduction
1.1 Energy demand
1.2 Hydropower
1.3 Low head hydropower – the HYLOW project
1.4 Hydrostatic pressure machine
1.5 Modelling approach
1.6 General Objectives
1.7 Research Questions
1.8 Outline of the thesis
Chapter 2 The Water – Energy nexus
2.1 Large Hydropower
2.2 Small Hydropower
2.3 Appropriate Technology
2.4 Small scale power generation
2.5 The HYLOW hydrostatic pressure converters
2.6 Environmental issues
2.7 Costs
Chapter 3 Hydropower take–off mechanics
3.1 Hydraulic machines
3.2 The HYLOW project
3.3 Design considerations
Chapter 4 Computational Fluid Dynamics
4.1 Governing equations
4.2 Free surfaces, volume of fluid (VoF) approach
Chapter 5 Application of 2D CFD modelling
5.1 2D Setup: Preprocessing
5.2 2D Analysis
5.3 Comparison of results
5.4 Discussion: 2D case
Chapter 6 Application of 3D CFD modelling
6.1 3D Setup: Preprocessing
6.2 3D Analysis
6.3 Comparison of results
6.4 Case 4
6.5 Discussion: 3D case
Chapter 7 Discussion
7.1 Small hydropower machines
7.2 Other HYLOW project findings
7.3 Small hydropower in a global context
Chapter 8 Conclusions and recommendations
8.1 Research Answers
8.2 Recommendations
Biography
Pradeep Narrain is a mechanical engineer who, after having worked on hydraulic modelling of components for transmission systems in the automobile industry, started work in the field of CFD. He has worked on various applied research projects involving external an internal flow modelling using CFD at the Institute of Applied Research "Energetic Systems", Esslingen University, Germany Upon completion of his MSc. in Water Resources and Engineering at the University of Stuttgart in 2009, he moved to UNESCO-IHE at Delft, the Netherlands to begin his PhD on very low head hydropower machines. His PhD focussed on low head hydropower, its importance on a global scale, its contribution to local power generation and the implementation of CFD for flow analysis. While continuing working on his PhD, he returned to Esslingen University in 2012 to work at the Faculty of Automotive Engineering. He is a tutor and laboratory engineer in the Laboratory for Car-Body Engineering. He works on CAD construction methodology of free-form surfaces using the industrial software-packages. He also works with CAD car-body models and design-space in a Virtual Reality environment, including Rapid Prototyping of CAD models, reverse-engineering and migration of laser-scan data of clay-models into a virtual/CAD environment.
