Investigation of the Aerodynamic Noise Generating Region of a General Electric T-58 Jet Engine by Means of the Simple Source/Fluid Dilatation Model

Abstract

Experimental tests were carried out at NASA Ames Research Center. Crosscorrelation measurements were made between the static pressure fluctuations, as measured with a B & K 14-in. microphone fitted with a nose cone, and the far-field radiated sound. These measurements were made for two different probe positions and a large number of far-field positions at various angles. In addition, each test geometry was run for jet exit velocities at four different Mach numbers. The measured, normalized cross-correlation functions varied between 0.155 and 0.004. These values depended upon the angular position of the far-field microphone, the jet exit velocity Mach number, and the position of the probe. In addition, the cross-correlation technique was employed to study the symmetry of the farfield radiated sound. Third-octave analysis of both the probe signal and the far-field radiated sound were made. The results of these measurements will be reported.