Statistical analysis of pressure fluctuations during unsteady flow for low-specific-speed centrifugal pumps

PEI Ji(裴吉), WANG Wen-jie(王文杰), YUAN Shou-qi(袁寿其)

(Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013, China)

Abstract:A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k–ω turbulence model. The distributions of pressure fluctuations in the impeller and the volute were recorded, and the pressure fluctuation intensity was analyzed comprehensively, at the design condition, using statistical methods. The results show that the pressure fluctuation intensity increases along the impeller streamline from the leading edge to the trailing edge. In the impeller passage, the intensity near the shroud is much higher than that near the hub at the inlet. However, the intensity at the middle passage is almost equal to the intensity at the outlet. The pressure fluctuation intensity is the highest at the trailing edge on the pressure side and near the tongue because of the rotor–stator interaction. The distribution of pressure fluctuation intensity is symmetrical in the axial cross sections of the volute channel. However, this intensity decreases with increasing radial distance. Hence, the pressure fluctuation intensity can be reduced by modifying the geometry of the leading edge in the impeller and the tongue in the volute.

Key words:transient; pressure fluctuation intensity; statistics; low specific speed; centrifugal pump