Numerical Investigation of Slot Variations on the Efficiency of Tangential Blowing at a Vertical Tailplane with Infinite Span

Kurzfassung

On a swept vertical tailplane with infinite span tangential blowing over the shoulder of a deflected rudder is applied. For large rudder deflection angles the flow on the rudder is separated without blowing. A numerical study is conducted with the aim to increase the side force coefficient. This could be required for example for a take-off condition with a one-sided engine failure necessitating the compensation of a large yawing moment. If this criterion is critical for the sizing of the vertical tailplane, active flow control like tangential blowing could help to reduce the size of the vertical tailplane and save weight and fuel. With a continuous slot it is demonstrated that the separation on the rudder can be reduced or avoided. It is shown that by using discrete slots this can be achieved with a smaller momentum coefficient. To analyze the effects of the discrete slots and their jets on each other and their effectivity with regard to the gain in side force coefficient a parameter study is conducted. The number of slots as well as the width of the slots in spanwise direction is varied and the impact of jet velocity changes is also studied. Comparing the results for a constant increase in side force and constant slot width the configuration with the smaller number of slots but a higher jet velocity proved to be the most effective one.