Cavitation Damage of Mechanical Pump Impellers Operating in Liquid Metal Space Power Loops

摘要

The three vaned centrifugal pump impeller, designed for high suction specific speeds, was endurance tested as part of a turbopump in 140 deg F potassium at a suction specific speed of 20,000 to determine the extent of cavitation damage. The endurance test was terminated after 350 hours due to performance deterioration and increased vibration. Post-test examination of the impeller showed mild cavitation pitting on inlet pressure surfaces of the vanes and variable amounts of damage on back channel pressure surfaces with a maximum penetration of about 0.050 inch. Complete water calibration of the impeller was done prior to the liquid metal test to determine cavitation patterns and tentatively select test conditions for the endurance test. Attempts were made to correlate cavitation noise with visual data during the impeller test. The complete turbopump was tested in water to determine collector effects on impeller performance and to finally select the endurance test point.