Comparison of experimental results of horizontal kaplan turbine with computational fluid dynamics

Hydropower has been the source of renewable energy for more than a century leading to reduction in burning of fossil fuels which has impact on the environment. More and more efficient hydro turbines have been developing for the power production with focus on the hydrodynamic behavior of the turbines. Emerging numerical codes specially designed to evaluate the efficiency of the turbine these days has made design of turbine a step ahead.

This project is contracted by AMJET Turbine System to evaluate the hydrodynamic, electrical and mechanical properties of a turbine prototype scaled to 1:7.828. The test stand was installed at the Hydraulic Model Annex#2 and the experimental fluid dynamics and data acquisition was performed by Joseph Longo, Research Engineer in IIHR - Hydroscience & Engineering.

The work on this thesis describes the numerical simulation of the prototype turbine at full load and partial load condition and comparison of the result with the experimental values for 30 feet of head at the runner outlet. Gridgen V15 and ANSYS Turbogrid has been used for high density mesh generation with total nodes of 1.3 million and ANSYS CFX 12.1 has been used to perform steady state analysis with backward Euler Scheme and Shear stress Transport as a turbulence model. Simulated results seemed to be best compared with experimental results for the optimum point and over predicted for over load condition. Therefore, another set of simulations were run for cases where the turbine was making maximum power at heads from 20 ft to 50 ft. For these values the output from the simulation follows the curve nature of the experiment. Total pressure on the mid span of the blade shows pressure below vapor pressure at the suction side of the blade at the leading edge which is due to the high flow velocity which creates low pressure at those regions.