PTV 계측법에 의한 극저비속도 원심펌프의 내부유동특성에 관한 연구

Abstract

In the range of very low specific speed (nSUBs/SUB＜0.25, non-dimensional), the perfomance of a centrifugal pump is much different from that of a centrifugal pump of normal nSUBs/SUB and the efficiency of the pump drops rapidly with the decrease of nSUBs/SUB. In order to examine the reason of unstable performance characteristics of the very low nSUBs/SUB centrifugal pump, the internal flow of the pump with a semi-open impeller is measured by a PTV(Particle Tracking Velocimetry) system. The purpose of this study is to make clear the internal flow characteristics and to obtain basic knowledge of the pump perfornance. The results show that the leakage flow through tip clearance give a strong effect on the flow pattern of impeller passage. A large vortex in the impeller passage and a strong reverse flow at impeller outlet are formed in the range of small flow rates, and the vortex and the reverse flow together reduce the absolute tengential velocity at the impeller outlet and cause the performance instability.