Spanwise-Inclined Jets in Supersonic Crossflow: Effects of Injection Pressure and Separation-Control Effectiveness

Abstract

Motivated by the advantageous performance of air-jet vortex generators (AJVGs) in controlling shock-induced flow separation, we aim at understanding the effects of relevant injection parameters on the physical mechanisms involved, as well as on the control effectiveness. We performed implicit large-eddy simulations to examine the influence of injection pressure on a spanwise-inclined jet in supersonic crossflow at Mach 2.5 and with momentum-thickness Reynolds number 7000. Four injection pressures were considered. The jet and jet/crossflow interactions strengthen with injection pressure, which is reflected in an enhanced obliqueness and asymmetry of the flow topology, strengthening the induced major counter-rotating vortex pair (CVP). This strengthening of the major CVP stagnates at a certain threshold, above which the flow blockage and momentum influx caused by the jets become so strong that they counter the positive influence on the CVP. Subsequently, we installed these jets in an AJVG control setup for a 24 deg compression-ramp interaction with separation to analyze the control effectiveness and interplay of the injection pressure and jet spacing. The strongest effects on control effectiveness are not related to the injection pressure itself, but to interactions between the jet-induced shocks and vortical structures. Therefore, there is a strong link between jet spacing and injection pressure regarding the control effectiveness. Based on these observations, we provide recommendations for designing efficient AJVG control setups.