Study of Control Devices Applied to a Transonic Shock Wave/Boundary Layer Interaction

Summary

The aim of this study was to investigate in detail the flow field resulting from transonic shock wave / boundary layer interactions under control conditions. Several control techniques have been investigated: 1) active control consisting in sucking a part of the boundary layer flow through a slot, 2) hybrid control, which is a combination of a passive control cavity placed underneath the shock region and a suction slot (or cavity) located downstream, and 3) control by a local deformation of the surface, the so-called bump concept. In the experimental part of the study, flow surveys have been executed with a two-component LDV system, including mean velocity and Reynolds tensor component measurements. Results show that active control by slot suction produces an increase in wave drag, but a significant decrease in friction drag, especially when the slot is located just downstream of the shock. The tendencies are inverted when bump or hybrid control is applied, the bump control having nevertheless a moderate effect on the friction drag. Moreover, active control by a slot efficiently diminishes the turbulence level downstream of the interaction domain. The aim of the theoretical study was to discuss the problems involved in the modeling of the vertical velocity component at the wall in the control region and of the effect of control on the turbulent field. The RANS research solver Nasca has been used for numerical simulations. Both, the algebraic Baldwin-Lomax model and the transport equation [k-ε] Chien model were investigated, the latter having shown deficiencies in the prediction of the channel flow. On the other hand, Poll’s law and the Bohning-Doerffer law give a similar and fair reproduction of the vertical velocity at the wall in the control region.