Enhancement of Control Jet Performance in Supersonic Crossflows Through Pilot Injection

Abstract

Injection of a control jet into a supersonic crossflow creates a large region of separated flow in the vicinity of injection, altering the pressure distribution on the parent body, and consequently the effectiveness of the injected jet in producing the desired control forces and moments. In the case of an axisymmetric parent body, this disruption typically results in a loss of effectiveness due to the spillover of the shock structures around the parent body. In this study, a novel technique for enhancing this jet effectiveness on bodies of revolution by means of employing a pilot injection upstream of the main control jet is proposed and evaluated at different external flow conditions. We show that diverting a small fraction ([Formula: see text]) of the primary control jet mass flow rate through an orifice situated five to 10 jet diameters upstream causes an earlier disruption of the external flow, leading to a weaker shock system around the primary injector. This reduces the extent of adverse interaction region and results in a lower spillover of the shock and vortical structures to the bottom side, leading to a significant improvement of the control effectiveness.