Abstract:In this study, a high-pressure multistage pump used in the combined cycle power plants is analyzed. The pump performance characteristics (differential head and efficiency) are numerically analyzed for different shapes of the radial diffuser. The design variables selected for the radial diffuser are, number of vanes, diameter ratio (D 4 /D 3 ), return channel outlet angle(α 6 ), and pressure recovery factor (C p ). The numerical analysis results showed that the differential head and efficiency are the highest when the diameter ratio is the highest. Further, it was observed that the differential head was lower when the return channel outlet angle was 60° than when it was 90°, because of pre-swirl at the diffuser outlet.

In this paper, we focus on using high-resolution implicit upwind shock-capturing scheme to avoid the formation of non-linear instabilities and numerical oscillations across shock waves or discontinuities. The governing equation is the compressible Reynolds Averaged Navier-Stokes equation based on the homogeneous mixture model. A preconditioned method is applied for enhancing efficient and accurate computations over a wide range of Mach numbers. For evaluation, the results from the present study have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained. Finally, the simulation of ventilated supercavitating flows over a torpedo with a hot propulsive jet was conducted to verify the efficiency of numerical scheme.

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