Turbulent Intensity in Supersonic Mixing Transition by Streamwise Vortices –Fluctuation Measurements by Hot-wire Anemometer and PIV–

Abstract

A key technological requirement for realizing a supersonic combustion ramjet (scramjet) engine is supersonic mixing enhancement. Streamwise vortices, which have larger circulation and break down more quickly into small-scale turbulent eddies, can be effectively used for supersonic mixing enhancement. In the present study, to clarify the condition for mixing transition in supersonic streamwise vortices, we performed visualization by the schlieren method as well as particle image velocimetry and hot-wire anemometry measurements of a supersonic mixing field that introduced streamwise vortices at the freestream Mach number M_∞ = 1.8. It was confirmed that the mixing transition state of streamwise vortices was spread over the whole vortex region owing to the shear layer instability at the outer edge and the unstable swirling motion of the streamwise vortices.