Design and Construction of a Mach 2 Wind Tunnel For Cavity Acoustics Research
Type of Degreethesis
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Cavity flow is encountered in many practical applications of ground and air vehicles operating at high speed. Examples include airflow past open windows, sunroofs, and wheel-wells of automobiles as well as landing gear and weapon bays of aircraft. Cavity flow becomes a design consideration at high-speeds hence research in the area of supersonic cavity acoustics is more motivated by military applications. In a typical cavity, the compressible shear layer separating from the front end of a cavity impinges on the rear wall and initiates a sequence of events consisting of intense edge tones, high decibel acoustics and resonance that leads to fluid-structure coupling, unsteady loads, and structural vibrations. Furthermore, the trajectories of the weapons released from an internal weapon bay become unpredictable resulting in the released store hitting the carrier. A Mach 2 wind tunnel was designed using the method of characteristics with a viscous approximation to conduct research is the area of cavity flow acoustics. Unique features of the supersonic wind tunnel include a modular design for quick changes in cavity configuration and optical access from all sides for qualitative and quantitative design techniques including multiple plane schlieren/shadowgraphy, anemometry, particle image velocimetry and high speed photography. The designed nozzle blocks and windows were machined on a CNC machine of the AE machine shop and assembled in the aerodynamics lab. Pressure signal histories and schlieren images suggest that the wind tunnel operated at designed values.