The effects of fueling rate and inlet distortion upon a cavity flameholder under a Mach 3 freestream have been examined through two-component 3 kHz particle image velocimetry. The oblique shock wave generated by the inlet of a scramjet flowpath has been approximated by an 8 degree shock generator attached to the isolator ceiling. Ensemble-averaged velocity statistics for the uniform inflow conditions show minimal correlation with the distribution of the combustion products (as identified by OH-PLIF visualization). The change in normal stresses with direct cavity fueling is consistent with the increased momentum flux through the fuel ports, suggesting that the cavity response may be explained through purely kinematic means. The addition of upstream fueling through a sonic port decreases the coherence of the recirculation zone within the cavity, and leads to non-uniform combustion. Visual inspections of the instantaneous velocity fields suggest this response is due to an amplification of the shear layer motion. Conversely, the response of the cavity in the distorted case is better correlated with the combustion behavior, in which regions of heat release exert a stabilizing effect upon the normal stresses. The methods for estimating the shear layer thickness are compared, and growth rates are computed for each test case.
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