TURBULENCE MEASUREMENTS IN SUPERSONIC JETS WITH OPTICAL DEFLECTOMETRY
Open Access
- Author:
- Day, Benjamin J
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- May 19, 2010
- Committee Members:
- Dennis K Mc Laughlin, Thesis Advisor/Co-Advisor
Dennis K Mc Laughlin, Thesis Advisor/Co-Advisor - Keywords:
- Jet Noise
Turbulence
supersonic
optical deflectometry
BBSAN
broadband shock associated noise
measurements
turbulence measurements - Abstract:
- Experiments have been carried out in the Pennsylvania State University High Speed Jet Noise Facility with the purpose of making turbulence measurements in high speed jets with optical deflectometry. Measurements are made in small scale jets issuing from axisymmetric nozzles at several supersonic jet Mach numbers. The jets studied include perfectly expanded and shock containing jets. Optical deflectometry is used to provide flow field turbulence measurements. Flow field spectra measured with the optical deflectometer are compared to other flow field measurements in high-speed jets gathered with different techniques. In addition, two point correlations in the shear layer are compared with PIV measurements. Good agreement in flow field measurements is found between optical deflectometry and other measurement techniques. Flow field measurements are successfully correlated with acoustic-field microphone measurements. Correlation measurements are presented for jets at several operating Mach numbers and show strong directivity in the rear arc of the jet. The strongest correlation is found at angles that suggest the noise from large scale structures is being measured. Noise source distribution is investigated with coherence spectra which show a clear shift to lower frequencies with increasing distance from the nozzle. Similar measurements performed in shock containing jets with microphones in the forward arc of the jet show coherence at the same frequency as the Broad Band Shock Associated Noise (BBSAN). These experiments suggest that optical deflectometry is a promising tool for studying jet noise generation in supersonic jets.