Mixing and Penetration Studies of Sonic Jets in a Mach 2 Freestream

Abstract

A comparison of the penetration and mixing characteristics of three transverse/oblique injector configurations is presented. The three geometries studied include circular transverse, circular oblique, and elliptical transverse injectors, and the crossflow is at Mach 2. Planar Mie scattering images of three near-field flow planes produced substantial information about the flowfield created by each injector. In addition to global flowfield characteristics, the Mie scattering images provided transverse and lateral penetrations for each injector. Instantaneous and time-averaged information concerning the structural organization of the flowfields was obtained. Results demonstrate increasing jet penetration in the transverse direction with increasing jet-to-freestream momentum flux ratio. Penetration of the oblique jet is appreciably less in the near-field compared to the two transverse jets due to the reduced component of momentum in the transverse direction. The transverse elliptic jet appears to spread more quickly in the lateral direction than the other two jets, suggesting that some type of axis-switchin g phenomenon occurs. Large-scale structures at the interface between the jet and freestream fluids are shown for the two transversely oriented jets, while small-scale eddies are prominent in the oblique jet flowfield. Near-field mixing appears dominated by these eddies and the counter-rotating structures that develop in the streamwise direction.