Prediction and analysis of jet pump cavitation using Large Eddy Simulation

3D LES numerical simulations were performed to investigate cavitation performance inside a jet pump. The results were found to match the test data most closely. The cavitation characteristics of the jet pump were then analyzed using changes in the inlet and outlet pressure to isolate its effect on cavitation. Both results shows that the increase of the inlet pressure generally increases the Renolds number but decrease the cavitation number, thus aggravate cavitation. The closing of the outlet valve increase the outlet pressure but decrease the flowrate ratio, resulting in the increase of velocity difference and vorticity in the mixing layer. So the cavitation first declines and then grows. The cavities appear slender and extended longer in the throat with high flowrate ratio. Conversely, the cavities look short and located in the front part of the throat with low flowrate ratio. Flow analysis indicated that the turbulence behavior in the shear layer and the overall mean pressure has great influence on the local pressure in jet pump, which reveal the reason of different cavitation shape observed in experiment.