Flow Field Simulation And Property Prediction For Hydraulic Turbine Runner

Accurate Simulation of flow field in hydraulic machinery will help us predict performance of different components (especially that of runner) with less expense. So it is becoming an essential tool for developing high quality runner in big factory. Until now, people have been looking for good methods which can work well in a wide operation condition range so that it can precisely predict machine抯 comprehensive performance including efficiency, cavitation property and stability. In this article, two turbulence models?RNG based k-e model and realizable k-e model ----are compared at first. Realizable k-e model is then adopted in the following calculation. SIMPLEC method is used for pressure-velocity coupling and finite-volume method is used for discretization. Comparation of Results from calculation and that of experiment shows that the results are reasonable. Further, Internal flow field is analyzed in detail and different flow field feature is found to connected with different runner performance. At last, different model with different geometry is calculated. The comparation of the results shows different geometry parameter has great influence on runner抯 performance such as flowrate, output, and efficiency and cavitation property. As part of research work on unsteady flow field in hydraulic machine, runner-guide vane-interaction (RSI) phenomena are explored by flow field simulation. Here, PISO method is used for pressure-velocity coupling, RNG bas~k-e model is adopted for turbulence modeling and Sliding mesh is used to deal with relative moving of two parts (runner and guide vane). The results from calculation are transferred by FFT and the frequencies of pressure oscillation in different point are obtained. Comparation of calculation results and measurement results shows good agreement. The reason for the appearance of middle frequency is analyzed. Then, the combination of runner blade number and guide vane number are examined. It shows that different combination of blade (vane) number will give different pressure oscillation frequency. Further calculation shows that the position angle of guide vane, distance between runner and guide vane all have some effect on the unsteady flow field caused by RSI and spiral case also has some influence on it.