Effect of air jet vortex generators on a shock wave boundary layer interaction

Abstract

The effect of upstream injection by means of continuous air jet vortex generators (AJVGs) on a shock wave turbulent boundary layer interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5°and a Mach number M e = 2.3. Considered are the effects of the AJVGs on the upstream boundary layer flow topology and on the spatial and dynamical characteristics of the interaction. To this aim, Stereoscopic Particle Image Velocimetry has been employed, in addition to hot-wire anemometry (HWA) for the investigation of the unsteady characteristics of the reflected shock. The AJVGs cause a reduction of the separation bubble length and height. In addition, the energetic frequency range of the reflected shock is increased by approximately 50%, which is in qualitative agreement with the smaller separation bubble size.

Control of shock unsteadiness in shock boundary-layer interaction on a compression corner using mechanical vortex generators

“…Recently, studies have been carried out to diminish the detrimental effects of SWBLI using flow control [11][12][13][14][15][16][17][18][19][20]. These techniques primarily rely on altering the characteristics of the incoming boundary-layer by adding momentum to the velocity profile close to the wall.…”

“…These techniques primarily rely on altering the characteristics of the incoming boundary-layer by adding momentum to the velocity profile close to the wall. The most popular method to accomplish this relies on the generation of vortices near the wall by the use of vortex generating (VG) devices such as micro-ramps, vane-type VG fixed at an angle to the main flow or the use of micro air-jets at an appropriate distance upstream of the region of interaction [12][13][14][15][16]. These devices generate either co-rotating or counter-rotating vortices depending upon their design and angular positions with respect to the main flow direction.…”

“…VG devices with a height 'h' of the order of boundary-layer thickness 'δ' have been used in the past to provide flow control in supersonic applications [15]. However, recent studies [12,13,[17][18][19] have revealed that sub-boundary-layer control devices (i.e., with h/δ of 0.1-0.4) to be more effective in suppressing wave drag and stabilizing the interaction region relative to conventional VG devices. However, the choice of placement location of the VG devices depends primarily on the type of interaction and the flow Mach number [13].…”

“…Alternate control methods include steady or pulsed air-jets, suction or bleed techniques [20]. Air-jet control methods also have the potential of integrating flow control with transpiration cooling [12]. Bleed however is known to reduce mass flow through the engine and is therefore a major cause of performance penalties which can be improved by using flow control methods [13].…”

Supersonic flow control

“…However, active flow control devices, as already mentioned before, can be complex, expensive and also difficult to implement and maintain [25]. Various groups in USA [29][30][31][32][33], Europe [10,28,34,35], UK [26,27], India [36,37] and China [38] are looking at different methods of shock-induced control in various areas of research applications.…”