Reduction of High Altitude Inlet Temperature Distortion at the Propulsion Systems Lab

Abstract

The Propulsion Systems Lab (PSL) at the NASA Glenn Research Center contains two large engine te st cells, PSL -3 and PSL -4, capable of simulating flight conditions up to 70,000 ft with a maximum forward air speed of Mach 3.0. The facility has experienced high levels of inlet temperature distortion at high altitude flight conditions. This report desc ribes how the inlet temperature profiles were improved for future jet engine testing. Temperature distortion levels were improved from 7 percent to 1.8 percent by modifying the cold air supply piping system. Flow angle and turbulence intensity were measu red in the plenum, upstream of the engine inlet, to investigate possible sources of distortion. As a result, plenum flow quality and turbulence intensity for PSL4 are documented in this report. I. Introduction he Propulsion Systems Lab (PSL) at the NASA Gle nn Research Center contains two large engine test cells, PSL -3 and PSL -4, capable of simulating flight conditions up to 70,000 ft with a maximum forward air speed of Mach 3.0. Recently, PSL -4 has been used for high altitude testing of small engines. High altitude test conditions are typically low speed and require cooled inlet air at temperatures down to -40 degrees F. The facility has experienced high levels of inlet temperature distortion at these simulated flight conditions. The temperature distortio ns are much higher than would be experienced during actual flight. This report summarizes an investigation into high levels of temperature distortion in the PSL -4 inlet plenum. The temperature distortion can cause undesirable effects on jet engine test ar ticles, such as reduced surge margin. Reduced surge margin can cause unstable test conditions, or can adversely affect experiments to determine surge margin. This report describes how the inlet temperature profiles were improved for future jet engine tes ting.