Type of Document	Dissertation
Author	Zhuang, Ning
URN	etd-04042007-121157
Title	Experimental Investigation of Supersonic Cavity Flow and Their Control
Degree	Doctor of Philosophy
Department	Mechanical Engineering, Department of
Advisory Committee	Advisor Name Title Farrukh S. Alvi Committee Chair Chiang Shih Committee Co-Chair Anuradha Annaswamy Committee Member Christopher Tam Committee Member Emmanuel G. Collins Committee Member
Keywords	Supersonic cavity Control Microjet PIV
Date of Defense	2007-03-22
Availability	unrestricted
Abstract The study of supersonic cavity flows is of interest both from fundamental fluid dynamics and practical perspectives. The complex nature of this flowfield, consisting of compressible shear layers, compression/expansion waves, and fluid-acoustic interactions, makes it a rich problem to study. A detailed experimental study of supersonic flow (M=1.5 to 2) over a range of three-dimensional rectangular cavities (L/D=1 to 5.2) was conducted. The measurements included unsteady surface pressure measurements, particle image velocimetry, and flow visualization using shadowgraph and schlieren. Large-scale structures in the shear layer and a large recirculation zone in the cavity was observed. Spatial and temporal mode switching was also observed, the nature being different for short and long cavities. The shear layer characteristics of the two cavities are very different in term of curvature and growth. Supersonic microjets were used at the leading edge of the cavities to suppress the resonance in the flow. With a minimal mass flux (0.15%), the activation of microjets led to a large reduction in cavity tones (20 dB) and overall sound pressure levels (9dB). In addition, the microjet injection enhanced the shear layer mixing and reduced the velocity fluctuation in the cavities. The significant reductions together with the low mass flux requirements make this a potentially viable technique for full-scale, practical applications.
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