Two-Phase Flow in Floating-Ring Seals for Cryogenic Turbopumps

Abstract

A flow visualization study on the two-phase flow in floating-ring seals for cryogenic fluid was carried out to identify the two-phase flow area (A₂) inside the sealing clearance induced by viscous frictional heating and the pressure drop. The effect of the two-phase flow area on leakage was investigated by comparing leakage measurements (Q) and the values of A₂ obtained from observed results. A₂ increased with increasing rotational speed; however, the increase of A₂ did not always bring about a decrease in the mass leakage rate. Moreover, the effect of the two-phase flow on the reduction of leakage was discussed by comparing the measurements of Q with the computational results (Q_liquid) obtained from the incompressible flow equation. It was confirmed that the effect of the two-phase state on the reduction in leakage can be broadly classified into the following two effects: effect of the all-liquid choked flow and effect of the two-phase flow area (A₂) inside the sealing clearance. In a high degree of subcooling conditions, the increase in A₂ tends to depress the reduction effect on the leakage rate.

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998

KEY WORDS:

• Two-Phase Seal
• Flow Rate
• Rocket Engines
• Cryogenic Lubricants

Notes

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998