Effects of Floating-Ring Seal Clearance on the Pump Performance for Turbopumps

Pumps for a turbopump generally operate under high rotational speeds and large-head-rise conditions. Therefore, reliability is a prime design requirement. Floating-ring seals are frequently employed in a turbopump because of robustness despite relatively high leakage losses. A number of studies have been performed on the floating-ring seal itself, but the effects of the floating-ring seal on the performance of the whole pump are not widely studied, in spite of their importance. The effects of floating-ring seal clearance on the hydraulic and suction performances of a pump are investigated by both experimental and computational methods in the present study. The experimental results showed that the head rise and the efficiency increased as the floating-ring seal clearance decreased. The results also showed that the leakage flow injected into the inducer inlet enhanced the suction performance of the pump by diminishing the size of the backflows. The strength of the backflow becomes weak as the injected leakage flow at the inducer inlet prevents the flow from prerotation.