Numerical Investigation of Tangential Blowing over the Rudder of a Vertical Tailplane

Abstract

On a vertical tailplane tangential blowing over the shoulder of a deflected rudder is applied. With large rudder deflection angle and without blowing the flow is mostly separated on the rudder. Three geometries are investigated in a numerical study with the aim to increase the side force coefficient. The first one is the baseline configuration without blowing, second a geometry with a continuous full span slot and third a geometry where discrete slots are used. With the continuous slot the separation on the rudder can be avoided completely while it is greatly reduced for the discrete slots. This is investigated for different sideslip angles. An approximately linear increase in the side force coefficient can be found until a sudden side force breakdown occurs. In a further study, the jet blowing velocity is varied. A smaller jet velocity leads to a smaller increase in the side force coefficient. Comparing the continuous and discrete slot configurations shows, that for a similar increase in the side force coefficient a much smaller mass flow rate is needed for the discrete slots. However, for jet velocities below the sonic speed the increase in the side force coefficient is limited. It can only be increased by a larger slot width in span wise direction but this comes at the expense of an increase in the required mass flow rate.