Experimental investigation of Goertler vortices in hypersonic ramp flows behind sharp and blunt leading edges

摘要

The objective of this paper is to analyze the influence of entropy layers on the formation of Goertler vortices in hypersonic compression ramp flows at different leading edges radii, flat plate lengths and ramp angles. Ramp models with a flat plate length of 50,100 and 150 mm at ramp angles of 15*, 20* and 25* with a sharp and blunt leading edges of up to 1 mm radius are experimentally investigated in the Aachen Shock Tunnel TH2 and the Ludwieg Wind Tunnel UT-1M at Mach number 8 and a unit Reynolds number of 41· 10~6 m~(-1). The Goertler vortices are analyzed in terms of entropy layer / boundary layer interaction, vortex wavelengths, and the spanwise heat flux variation. The shock wave / boundary layer interaction influencing the Gortler instability is studied with peak heating correlations and separation lengths. Thermocouples, thermal sensitive paint, pressure sensors, schlieren imagery and infrared imaging are used to obtain the experimental data. Beyond the reversal radius, for all ramp angles and flat plates, the entropy layer / boundary layer interaction leads to a reduction of the peak heat flux and the spanwise variation at reattachment.