ANALYSIS OF INTERMITTENCY AND PROBE DATA IN A SUPERSONIC-FLOW WITH

Probe measurements were performed in the flow field produced by inject ion of helium or air into a supersonic airstream. The injectant was se eded with water and Rayleigh scattering was used to image the injectan t plume. The region of the flow containing injectant-air mixture is se en to be highly unsteady, leading to the intermittent presence of inje ctant in certain regions. The intermittency is inferred. It is shown t hat bias errors can occur when the probe data is analyzed by technique s which assume steady flow. A technique for relatively bias-free analy sis utilizing the intermittency measurements is presented and the bias errors are estimated. The gas-sampling probe is shown to measure the mass-weighted-mean mass fraction of helium, which is significantly les s than the simple mean. ii new measure of mixing efficiency obtained f rom the combined probe and intermittency measurements is discussed.