Date of Award

5-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Aerospace Engineering

Major Professor

Ahmad D. Vakili

Committee Members

Reza Abedi, Trevor M. Moeller, Andrew Yu

Abstract

This study presents results of innovative integration of passive and active flow physics to accomplish effective supersonic mixing. The study is continuing cavity flow control research in the supersonic wind tunnel at the University of Tennessee Space Institute (UTSI). Initially numerical simulations were employed in support of choosing and refining the experimental configuration designs. Mixing enhancement was achieved through innovative coupling of aerodynamics of corner vortex flows and cavity flow control jets. The two geometries were chosen for their potential to generate strong streamwise vortices, weaker shock losses, low drag, and cavity recirculation zones. Another consideration was that the two physically different concepts would be studied to provide better understanding of the innovative mixing. Jets, simulating fuel injection, were used for flow control provided through penetrations in the front face and side walls of the cavity. Flow visualization, dynamic pressure (sound pressure level) data are measured and PIV measurements are presented and compared with computational predictions for several geometries. High frequency dynamic pressure data were recorded to determine the cavity flow acoustic patterns. Measurements were acquired by a digital data acquisition system from two dynamic pressure transducers, located at different locations on the floor of the cavity. PIV measurements of selected configurations were performed. Schlieren and PIV images, pressure spectra and 2-D PIV data obtained are used as a basis for understanding the flow processes involved and comparison for improving the overall mixing and penetration performance. Streamwise vortices were generated using two different innovatively designed geometries, strategically located upstream of selected cavity configurations, including various jet arrangements, simulating fuel flow and control. Both configurations tested developed relatively strong streamwise vortex flows and weakened or lofted shear layers, indicating that mixing was enhanced. The two configurations exhibited flow changes with the simulated fuel injection. However, different injection arrangements by the simulated fuel jets resulted in different details in the flow fields and their resulting acoustic spectra. The resulting flow fields show improved potential for fuel flow mixing and increased penetration while amplifying or attenuating flow unsteadiness in the cavity.

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