An Experimental Investigation Into The Effect Of Plasma On The Flow Features Of An Axisymmetric Jet

The main goal of the research presented was to determine the differences between a plasma field and neutral field flow structure (both mean and turbulent effects) for varying Mach number. The overall objective was to describe the effect of radio frequency capacitively coupled plasma on the flow features of compressible axisymmetric jets in Nitrogen. Three flows were investigated: perfectly expanded jets, highly underexpanded jets, and jets created by a constant-diameter nozzle which produced developing pipe flow. High subsonic to supersonic pressure ratios were investigated to determine the influence of compressibility. Particle image velocimetry was used to quantify the mean and turbulent fluctuations of velocity in the jet flow field. The tracking of seed particles in rarefied and compressible jets was characterized by comparison with particle models and from mean velocities obtained by molecular tagging velocimetry. Periodic, large scale structures were forced into the jet field and convective velocities were measured by tracking the structures. The plasma fields were measured to characterize the visible light emitted and rotational and vibrational temperatures were obtained by model matching to spectra recorded of the second positive system of diatomic Nitrogen. The original document contains color images.