Numerical study of the influence of the inlet flow in a practical water-pump intake

The U(2)RANS CFD model (Lai et al. 2000) is employed to perform the calculations of a real-world intake, and the results (Li 2001) are compared with the laboratory model experiments conducted by Nakato et al. (1999). Although the numerical simulations have a good agreement with the experimental data in the velocities at the pump-pipe throat, as judged from the relative errors, the calculated velocity deviations along concentric circles inside the pipe are lower than the corresponding experimental data. Thus, further studies were conducted on the influence of the inlet flow, in order to find out whether that disagreement was caused by the inaccuracy of the predictions at the pump bay entry. Four different inlet conditions were simulated. It is shown that: a) the flow swirl inside the pump column is sensitive to the inlet flow, b) the velocity distributions at the pump throat are not sensitive to the inlet flow, and c) the inaccuracy of the predictions of the inlet flow at the bay entry is not the major reason for the disagreement of velocity deviations along concentric circles at the pump throat between the numerical and experimental results. The reason for that insensitivity and disagreement may arise from the inadequacy of the standard k(-epsilon) turbulence model with wall functions to this case.