To study the near field of a small aspect ratio elliptic jet in the presence of annular flow at subsonic speed a coaxial jet facility is developed in the ExperimentaludAerodynamics Division of NAL. The Jets are driven by compressed air from the central compressor. The two jet velocities are independently controlled using pressure regulating valves to set the required pressure in settling chambers. A virtual Instrumentation based controls and data acquisition system was developed for the pressure and velocity measurements. The top hat jet exit velocity profile and the low exit turbulence intensity measured using hotwire prove the design efforts taken in building this facility. A study of the near field of an elliptic jet in the presence of external co flow using Particle Image Velocimetry (PIV) is carried out for two chosen velocity ratio. PIV being a unique tool that provides both time averaged flow statistics as well as the instantaneous flow field has brought out various flow features of the near field elliptic jet in the presence of annular co flow that are discussed in this report.
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