Effects of tip clearance on performance and characteristics of backflow in a turbopump inducer

Abstract

The objectives of the present study were to investigate the effects of tip clearance on the performance and flow characteristics of a turbopump inducer by using computational fluid dynamics. Three different tip-clearance sizes were analyzed for design and off-design conditions. The numerical results were validated by comparison with experimental results. Our detailed investigation of the simulated flow fields shows that backflow penetrates farther upstream for large-tip clearances, which means that performance declines rapidly. On the other hand, for small-tip clearances, the extent of backflow is reduced but the development of hub separation in the middle of the passage causes performance degradation. Our results confirm that a particular value of the tip-clearance limits the development of secondary flow in the passage.