An experimental study of supersonic conical cooling films subjected to different ratios of static pressure

Abstract

Research into the flow mechanisms and heat transfer characteristics of two-dimensional supersonic cooling films has been extensive, yet studies on supersonic conical cooling films remain scarce. This study examined the flow characteristics and mechanisms of supersonic conical cooling film under varying ratios of static pressure (RSPs) using nanoparticle planar laser scattering and particle image velocimetry techniques. The mainstream Mach number was Ma∞=3.8, and the supersonic conical cooling film was tangentially injected through a precisely calibrated annular nozzle of Maj=2.8. Analysis of the instantaneous flow structure characteristics along and normal to the flow direction segmented the flow downstream of the slot into three distinct zones: the potential core region, the large-scale coherent structure region, and the turbulent boundary layer region. The reattachment location was assessed both qualitatively and quantitatively based on time-averaged and statistical velocity field data. The results indicated that the reattachment location extended with higher RSP. Moreover, the reattachment point of the supersonic conical cooling film was further forward than that of a two-dimensional supersonic cooling film. It was found that the supersonic conical cooling film was more significantly affected by the compression effect of the conical stream tube compared to the impact of RSP.