Effect of Microvortex Generators On Seperated Normal Shock/ Boundary Layer Interactions

Abstract

Experiments have been performed in a blowdown supersonic wind tunnel to investigate the effect of subboundary layer vortex generators placed upstream of a normal shock/turbulent boundary layer interaction at a Mach number of 1.5 and a freestream Reynolds number of 28 10 6 . The Reynolds number based on the inflow boundary layer displacement thickness was 26,000. Two types of subboundary layer vortex generators were investigated: wedgeshaped and counter-rotating vanes. It was found that the vane-type subboundary layer vortex generators eliminated and the wedge-type subboundary layer vortex generators greatly reduced the shock-induced separation. When placed in the supersonic part of the flow, both types of subboundary layer vortex generators caused a wave pattern consisting of a shock, reexpansion, and shock. The reexpansion and double shocks are undesirable features because they equate to increased total pressure losses. Furthermore there are indications that the vortex intensity is reduced by the normal shock/boundary layer interaction. Overall, the vane-type subboundary layer vortex generators were the more effective devices as they eliminated the shock-induced separation and had the least detrimental effect on the shock structure. Nomenclaturefreestream flow velocity, ms 1 u = local flow velocity, ms 1 X = streamwise coordinate, mm Y = vertical coordinate, mm Z = spanwise coordinate, mm = boundary layer thickness, mm = boundary layer displacement thickness, mm R 0 1 u= e U e dy = boundary layer momentum thickness, mm R 0 u= e U e 1 u= e U e dy Subscripts 0 = total conditions 1 = upstream of shock 1 = freestream

Effects of Micro-Ramps on a Shock Wave/Turbulent Boundary Layer Interaction

“…Although experimental studies (see [15,16]) suggest that vane-type SBVGs may be more effective in suppressing separation, micro-ramps offer the advantage of being more rugged, therefore less subject to mechanical failure, which is essential for engine intake applications. Within this context, the present paper reports on an exploratory study conducted to investigate the effects of SBVGs on an incident SWTBLI using PIV.…”

Numerical and Experimental Investigations of the Supersonic Microramp Wake

“…Babinsky [5], the effect of micro ramps and micro vanes installed upstream of a normal shock wave was investigated and a reduction of flow separation was observed. Also, the mechanism of the streamwise pair of vortices, initially visualized in subsonic flows [2,3], was also revealed in the supersonic regime.…”

LES investigation into the generation of momentum deficits in the supersonic wake of a micro-ramp

“…Abundant efforts have been recently devoted to investigate the flow properties through both numerical [9][10][11][12] and experimental [13][14] methods. The major features including the momentum deficit and the primary vortex pair were originally visualized by Holden and Babinsky through wind tunnel experiments [5] . These features were later confirmed qualitatively by the LES results of Lee and Loth [2] .…”

“…The positive effects of the micro-ramp have been reported in the preceding researches. A typical application is intended for separation reduction produced in a shock wave/boundary layer interaction (SWBLI) [2][3][4][5][6][7][8] . Although the effects have been demonstrated through the foregoing studies, the flow physics of the microramp has not been fully understood due to the complex geometry of current device.…”