Honors Theses

Quantitative Concentration and Density Measurements in Subsonic and Supersonic Helium Jets Using Rainbow Schlieren Deflectometry


Taber Wanstall, Ph.D.


Mechanical and Aerospace Engineering

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Honors Thesis


Rainbow Schlieren Defectometry (RSD) has been applied to acquire quantitative concentration and density measurements in both subsonic and supersonic conditions. Experiments were conducted using a helium jet expelled into air for two distinct regimes: initially laminar, momentum-driven at subsonic speeds, and subsequently at supersonic speeds. Comprehensive full-field measurements were captured, encompassing the laminar, transition, and fully turbulent regions of the jet in both subsonic and supersonic conditions. The subsonic (momentum-driven) regime was validated against Rayleigh scattering data in the literature. The supersonic regime utilizes a novel approach for acquiring density, where the mixing field is delineated into three portions: the potential core, the non-isobaric mixing shear layer, and the isobaric far field. Results from the RSD technique demonstrate robust mixing measurement capabilities for both subsonic and supersonic applications. The results from this work show promise for future applications involving the use of quantitative RSD for fuel injection studies.

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