Analysis of simulated planar waves using an air jet distortion generator in a gas turbine engine ground test facility

This Thesis evaluated the qualitative and quantitative features of unsteady total-pressure distortion introduced into the inlet of a gas turbine engine during test in a ground test facility. The distortion was created in the form of spatially uniform planar waves that travel normal to the engine face and have discrete frequencies of five and fifteen Hertz. These frequencies are representative of typical sinusoidal planar waves encountered during flight tests of various high-performance jet aircraft. An Air Jet Distortion Generator (AJDG) created the waves in the Arnold Engineering Development Center's (AEDC) Aeropropulsion Systems Test Facility (ASTF) test cell C-1 in an attempt to simulate a planar pulse inlet distortion pattern. Spatial distortion descriptors for radial intensity and circumferential extent and intensity using SAE Aerospace Recommended Practice (ARP) 1420 guidelines were calculated to evaluate the spatial uniformity of the generated planar wave. Additionally, a Fast Fourier Transform (FFT) technique was used to determine the spectral content of the waves. Analysis indicated that the waves are representative of a spatially uniform, discrete planar wave. The AJDG did not add an appreciable amount of spatial distortion, no more than approximately 2.0%, and overall levels of distortion are comparable to those seen in typical direct-connect type test configurations. Also, spectral analysis indicated the frequency content of the waves was concentrated in the desired bands.