Stabilization of crossflow instability with plasma actuators: linearized navier stokes simulations

This paper describes work carried out within the Buterfli project to look at the control of transition causing “target” stationary cross flow vortices, by the use of distributed plasma actuation to generate sub-dominant “killer” modes. The objective is to use the “killer” modes to control the “target” modes through a non-linear stabilising mechanism. The numerical modelling and results are compared to experimental studies performed at the TsAGI T124 tunnel for a swept plate subject to a favourable pressure gradient flow. A mathematical model for the actuator developed at TsAGI was implemented in a linearised Navier Stokes (LNS) solver and used to model and hence predict “killer” mode amplitudes at a measurement plane in the experiment. The LNS analysis shows good agreement with experiment, and the results are used as input for non-linear PSE analysis to predict the effect of these modes on crossflow transition. Whilst the numerical model indicates a delay in transition, experimental results indicated an advance rather than delay in transition; this was determined to be due to actuator induced unsteadiness arising in the experiment, resulting in the generation of travelling crossflow disturbances which tended to obscure and thus dominate the plasma stabilised stationary disturbances.