Shuttle Plume Impingement Flight Experiment (SPIFEX) - Heat flux measurements and predictions

Abstract

The Shuttle Plume Impingement Flight Experiment (SPIFEX), which was flown on Mission STS-64 in September 1994, was designed to study the characteristics of the Orbiter Reaction Control System (RCS) jet plumes impinging upon a target placed some 10 to 25 meters from the jet exit plane. During docking of the Orbiter with the Russian Mir and the International Space Station (ISS), plume environments can have an adverse effect on surrounding structures such as solar panels and radiators. Prior to SPIFEX, flight test data was lacking which characterized pressure, loads and heat flux environments from exhaust plumes, especially for scarfed nozzles, dual-jet configurations, and pulsed firings. The objective of the present paper is to present the SPIFEX heat flux measurements and compare with predictions from a plume impingement heating model. The heating data and predictions are compared for both single and dual-jet firings as a function of distance from exit plane to heat flux sensor, azimuth angle from the plume axis, clock angle around the scarfed nozzles, impingement angle at the surface, and impingement pressure. Results were generally within 10 to 15% of predictions, especially for the single jet firings.