CFD Investigation of the Influence of Volute Geometrical Variations on Hydrodynamic Characteristics of Circulator Pump

摘要

Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D_3, A_8, a_0, j_0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D_3 and A_8 are major influence factors on hydrodynamic characteristics of the pump, while a_0, j_0 and Rt are minor influence factors. The minimum contribution from both D_3 and A_8 is 58% on head, and maximum contribution from both D_3 and A_8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D_3/D_2 and A_8/A_(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D_3/D_2. While for the other volute parameters a_0, j_0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force.