An Indirect Approach for Flow Pattern Transition Identification Inside a Low-Specific-Speed Centrifugal Pump with Experimental Verification and Theoretical Modeling

Abstract

Summary Of significant importance to the multiphase flow, the gas/liquid two-phase flow patterns and the transition boundaries between them are extremely difficult to be characterized inside the centrifugal pumps because the steel-made nontransparent casing shrouds the impeller’s flow passages. How to visualize the internal flow patterns within the rotating impeller has drawn considerable attention. In this study, an indirect approach proposed by Gamboa and Prado (2011) to recognize the gas/liquid flow patterns in the centrifugal impeller via inflection characteristics of H-Q performance curves is used and verified by both experimental tests and numerical simulations. To further validate the indirect flow pattern recognition approach to a low-specific-speed centrifugal pump, the acrylic-made transparent impeller was adopted to conduct experimental testing, in which the internal two-phase flow pattern can be visualized by a high-speed camera. The 3D numerical simulation was performed and compared with corresponding visualization experiments to illustrate the two-phase flow structures. The preliminary results reveal that the inflection characteristics on the H-Q performance curves of the centrifugal pump can be regarded as the flow pattern transition boundaries under various flow conditions. The experiments and simulations conducted for this paper further validated an existing mechanistic model to predict flow pattern transitions.