Pressure measurements of coaxial jet of high mean-velocity ratio

This paper describes an experimental investigation of the initial region of a subsonic cold coaxial jet at a mean-velocity ratio lambda, outer to inner, of 1.25. Detailed measurements in the initial region have shown that similarity of the pressure intensity profiles exists in the three zones: the initial merging zone, the intermediate zone and the fully merged zone. Spectral measurements of the pressure fluctuations confirm the existence of coherent structures in the outer mixing region. Comparison of the coaxial jet results with those of the single jet has been attempted.