Numerical simulation of turbulence flow in a Bulb turbine

In this paper, high accuracy performance prediction method based on entire flow passage for a Bulb turbine is presented. The performance is predicted by solving steady and unsteady Reynolds-Averaged Navier-Stokes equations, Large Eddy simulation and Detached Eddy Simulation. The prediction accuracy was evaluated to compare with the model test results for efficiency characteristic, pressure fluctuation characteristic and velocity distribution at runner inlet and outlet of NQE 0.8 Bulb model turbine. As for the efficiency near the on-cam condition, it is possible to determine with high accuracy in the steady RANS analysis. However, for the analysis accuracy regarding pressure fluctuation characteristic and turbine characteristics at off-cam operating condition, it found that there is a need to further study. Evaluated prediction method for the turbine flow and performance is introduced to facilitate the future design and research works on Bulb type turbine.