High-Speed, High-Temperature Finger Seal Test Results

Abstract

A pressure balanced finger seal was tested in NASA's High-Temperature, High-Speed Turbine Seal Test Rig at conditions up to 922 K, 366 m/s, and 517 kPa to study its leakage, power loss, and wear performance at advanced engine conditions. Static, performance, endurance, and postperformance tests were conducted. The finger seal leakage performance met the flow factor goal of 7.72 kg-∫K/MPa-m-s during the endurance test, which simulated expected advanced-engine rated power conditions. The maximum finger seal power loss of 10.4 kW occurred at 366 m/s and 517 kPa across the seal. Further design improvements are needed to reduce seal power loss. Finger seal power loss is comparable to measured brush seal power loss. Most finger seal wear occurred in the initial performance test and the accumulative seal weight loss leveled out over time. With approximately one-half the finger pad thickness remaining after 11 h of testing, the rate of seal wear is acceptable. Furthermore, the high velocity oxygen fuel thermally sprayed (HVOF) chrome carbide coating on the rotor performed well, with a final wear track depth less than 6.35 μm. The finger seal is very sensitive to clearance, and further testing is required to separate and quantify the effects of changes in radial clearance from apparent hysteresis.