Numerical Simulation on the Steady and Unsteady Internal Flows of a Centrifugal Pump

Abstract

Nowadays, pumps of different size are needed for a great variety of purposes. In the past, both computational fluid dynamics (CFD) and experimental flow visualization were performed to reveal flow characteristics within centrifugal pumps, to examine a specific design and to guide design improvement (see Burgreen et al. 1996, 2000). Li et al. (2007) studied the interior viscous flow in a mini pump with an asymmetric axis using CFD and PIV (particle image velocimetry) for improvement of the pump design. Matsui et al. (2002) adopted the the k-ω model in the CFD simulation for a centrfugal pump, and the computational grid system only consisted of one flow passage for LDV (laser Dopler velocimetry) test impeller. Byskov et al. (2003a) and Pedersen & Larsen (2003 b) investigated the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller using LES simulation and PIV and LDV measurements. The velocities predicted with LES were in good agreement with the experimental data. The two RANS simulations were, however, not able to predict this complex flow field. It was thus found that using LES for analyzing the flow field in centrifugal pumps could shed light on basic fluid dynamic with a satisfactory accuracy compared to experiments. A transient simulation was used to study the effects of pulsatile blood flow due to the heartbeat through blood pumps by Song et al. (2003). The microsized geometry of the pump made the choice of turbulence models significant for the accuracy of calculation. The comparison showed that the k-ω model gave better predictions of the shear level within the near wall regions than the k-e model. Guleren and Pinarbasi (2004) indicated that the stallcell size extended from one to two diffuser passages. Comparisons of the computational results with experimental data were made and showed good agreement. The unsteady flow in a low specific speed radial diffuser was simulated by the CFD code CFX-10 by Feng et al. (2009). The PIV and LDV measurements had been conducted to validate the CFD results. Both the phase-averaged velocity fields and the turbulence fields obtained from different methods are presented and compared. In this study, in order to get more information about the internal flow of a centrifugal pump, both experimental measurement and numerical simulation are engaged. A centrifugal model pump test rig is built for PIV measurement. The test, involving the technology of index match and fluorescent, is for acquiring flow pattern in a fixed rotational speed, the velocity distribution of the flow field are thus obtained. And, the RANS (Reynolds