Combined Stereo-PIV and PLIF Measurements of Transverse Injection in Mach 2 Supersonic Flow

A combined stereoscopic particle image velocimetry (PIV) and acetone planar laser-induced fluorescence (PLIF) measurement system was developed to investigate turbulent mixing of a jet into a supersonic flow. The measurement was performed using a supersonic wind tunnel. Air was injected perpendicular into a Mach 2 freestream with a jet-to-freestream momentum ratio of 2.2. The system successfully measured the molar concentration of the jet using PLIF and the velocity in the flow-field using PIV simultaneously. These data yielded turbulent eddy diffusive flux that is a product of fluctuating velocity (v') and concentration (c'). The eddy flux of the streamwise component (c'u') was negative, and that of the heightwise component (c'v') was positive in the outer jet boundary region. Large-scale structures were periodically generated in the outer jet boundary and convected downstream. This large-scale motion induced negative c'u' and positive c'v' in the outer jet boundary. In the inner region of the jet, the air entrained by the counter-rotating vortices induced a positive v' and negative c' region, resulting in negative c'v'.