Optimization of hydroturbine design using CFD

Abstract

In this thesis, research on the possibility of increasing the efficiency and torque generated by a turbine is done. The turbine is driven by a flow that is pumped through pipelines by utilizing the kinetic energy of the flow. A manual optimization study is done by running CFD simulations on different turbine geometries with different number of blades (5-7) and blade angles. The CFD simulations were run with an open source software called OpenFOAM. The simulations use an automatic meshing tool called snappyHexMesh to generate necessary geometries. The traditional k- model was used for the turbulence modelling. A comparison of torque output from two different approaches (AMI and MRF) was evaluated. The relative difference of torque of these approaches was low. Therefore, the steady-state MRF-approach was used due to its much shorter simulation time. In the attempt to validate the existing turbine design to experimental data, the torque outputs were unexpectedly low. Thus, it is concluded that the simulation set-up for the CFD analysis can be improved. However, the relative differences in this project is assumed to be the same. For an operational volume flow of 1313 l/min, larger stagger angles and inlet flow angles of the turbine blades reflected an increase of torque for all number of turbine blades evaluated. Lower number of turbine blades showed a higher efficiency, and lower static pressure drop. The best design in this project, show an increase of 21.56% efficiency and 27.3 % torque, compared to the pilot design.