Study on Cascade Density of the Impeller Based on Response Surface Analysis

Abstract

In order to improve the cavitation performance of hydraulic machinery in the design stage, the response surface analysis method is used to study the influence of cascade density on the hydraulic characteristics and cavitation characteristics of a three-dimensional rotating hydrofoil. For this method, an axial flow impeller with a specific speed of 750 is selected as the experimental object. Nine groups of three-dimensional rotating hydrofoils with different cascade densities were designed by the D-optimal quadratic sampling method. The impeller and guide vane were structured and meshed by TurboGrid. The inlet and outlet extension sections were structured and meshed by ICEM. Grid independence analysis was carried out. The hydraulic characteristics and cavitation characteristics of nine groups of hydrofoils were calculated by CFD numerical simulation. The calculation results of nine groups of schemes were analyzed from three angles of external characteristics, flow pattern and cavitation performance, and the better schemes under each analysis angle were obtained. By means of response surface analysis, more external characteristics and cavitation characteristics of different cascade densities will be filled. Finally, combined with the response target, the influence of cascade density on each target is analyzed and the comprehensive selection range of hub and shroud is given. This method can improve the rationality of sampling, and select a more suitable range of cascade density by designing fewer impellers.