Numerical Investigation of Unsteady Tangential Blowing at the Rudder of a Vertical Tailplane Airfoil

Abstract

A numerical 2D investigation of a vertical tailplane airfoil using active flow control with tangential blowing over the rudder shoulder is conducted. The aim of the flow control application is to increase the maximum lift or side force which can be created by the vertical tailplane at critical conditions like the one engine-inoperative failure case. On the highly deflected rudder a large separation can be found without blowing. With constant tangential blowing it was shown that fully attached flow can be achieved. To increase the efficiency, pulsed blowing is applied here, leading to a similar increase in the lift coefficient at a reduced actuation mass flow required. Parameters like the blowing momentum coefficient and the dimensionless frequency are varied and the results are compared to those of the flow calculations with constant blowing. It is observed that pulsed blowing with a small momentum coefficient leads to a strong increase in the lift coefficient compared to constant blowing. The resulting lift increment depends on the dimensionless frequency selected.