The spatial evolution of acoustic waveforms produced by a Mach 3 jet are investigated using both 1/4 inch and 1/8 inch pressure field microphones located along rays emanating from the post potential core where the peak sound emission is found to occur. The measurements are acquired in a fully anechoic chamber where ground, or other large surface reflections are minimal. The calculation of the OASPL along an arc located at 95 jet diameters using 120 planar grid measurements are shown to collapse remarkably well when the arc array is centered on the post potential core region. Various statistical metrics, including the quadrature spectral density, number of zero crossings, the skewness of the pressure time derivative and the integral of the negative part of the quadrature spectral density, are exercised along the peak emission path. These metrics are shown to undergo rapid changes within 2 meters from the source regions of this laboratory scale jet. The sensitivity of these findings to both transducer size and humidity effects are discussed. A visual extrapolation of these nonlinear metrics toward the jet shear layer suggests that these waveforms are initially skewed at the source. An experimentally validated wave packet model is used to confirm the location where the pressure decay law transition from cylindrical to spherical. It is then used to estimate the source intensity, which is required to predict the effective Gol'dberg number. / text

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Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 175-182).

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The Supersonic tunnel located in Patterson Labs at Mississippi State University has been thoroughly documented for future reference purposes. Data acquisition, physical components, shutdown devices, a control program, and the hydraulic system are all discussed in detail. Analysis is performed showing that the flow within the Mach 2 nozzle only reaches Mach 1.8 for a portion of the flow, but that this portion of the flow is relatively stable for a wide range of settling chamber pressures. It is concluded that the tunnel with the nozzle blocks used functions correctly.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 61-62). Also available via the Internet.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering 2016 / The nozzle contour profiles of the CSIR’s supersonic wind tunnel (high speed wind tunnel) were designed to produce smooth, uniform and shock-free flow in the operating section of the facility. The existing profiles produce weak waves in the test section region which induces flow gradients and flow angularities in the air flow, effectively degrading the air flow quality, which in turn perturbs the wind tunnel data. The wind tunnel geometry and tunnel constraints were employed in accordance with the method of characteristics technique to design the supersonic nozzle profiles. The Sivells’ nozzle design method was deemed the most feasible which calculates the profile downstream of the inflection point. The throat block profile was amalgamated with this profile to yield a profile from the throat to the test section. A boundary layer correction was applied to the profiles to account for viscous effects which cause a Mach number reduction from the desired test section Mach number. An automatic computation was used for the profile design and a computational method analysed the Mach distribution, flow angularity and density gradient (to determine the occurrence of shocks and expansions) of the profiles implemented in the tunnel, for the full Mach number range of the HSWT. The methods used, achieved uniform and shock-free flow such that the Mach number and flow angularity were within the acceptable quality limits of the HSWT.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 72-74). Also available via the Internet.