Abstract： In order to clarify the mixing process between the working fluid and the sucked fluid in a jet pump, several twoequation turbulence models (Standard k-ε, RNG k-ε, Realizable k-ε and SST k-ω model) and Large Eddy Simulation model were used to calculate 3D singlephase flow field in the pump, and the numerical results were compared with the experimental data. The results showed that the pressure ratio and efficiency obtained by LES model agreed well with the experimental data. All the above twoequation turbulence models overestimated the energy dissipation during the mixing process and the vortex structure in the mixing layer was not well predicted by them. Just the LES model, however, showed the coherent vortex structure in the mixing layer, which precisely reflects the transport of momentum and energy, and the mixing process between the working fluid and sucked fluid. Further the predicted characteristic curves by LES achieved better agreement with the experimental observations than those by the rest turbulence models. Then LES was chosen to simulate the internal flow of the jet pump at different flow ratios. The results showed that the mixing zone between the working fluid and the sucked fluid moved away from the throat to downstream with increasing flow ratio; consequently the core flow with high velocity is stretched along the axial direction and the axial velocity of the mixed fluid is also increased.
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