An Experimental Study of Supersonic Flows Over an Elliptic Cone

Abstract

Abstract : An elliptic cone similar to the one used by other investigators, a 4:1 aspect ratio elliptic cone with the cone angle on the major axis of 17.5 deg and 4.5 deg along the minor axis, in a Mach 2.8 tunnel was used in the present work. The Reynolds number used in this work was much higher than that used in other experimental work. The purpose is to examine the transition process as well as the turbulent structure of a three-dimensional boundary layer after transition. The primary focus of this study is on the structure of the turbulence, which was explored using advanced optical diagnostics. Both surface flow visualizations and Filtered Rayleigh Scattering (FRS) based flow visualizations were used in this study. The results showed that the boundary layer developing along the major centerline, the flattest region on the cone surface, underwent transition to turbulence approximately 35 mm downstream of the cone tip. Surface cross flow was observed primarily near the minor centerline of the cone, the area with the largest curvature. No cross flow was observed around the major centerline after 10 mm downstream of the cone tip.