Performance enhancement of a vertical stabilizer using synthetic jet actuators: Non-zero sideslip

Synthetic jets operating at a dimensionless frequency O(10) have been shown to be effective in improving the performance of aerodynamic bodies. Application of flow control to a vertical stabilizer of an aircraft could enable significant reduction in its size, with corresponding reductions in drag, weight and fuel costs. Wind tunnel experiments at a Reynolds number of 350,000 were conducted on a swept back, tapered vertical stabilizer capable of sideslip rotation and with a 33% rudder chord. The model was approximately 1/19^th scale, used a NACA 0012 airfoil section and had twelve synthetic jet actuators distributed along the span, just upstream of the rudder hingeline. With active flow control and in the presence of a boundary layer trip, the side force was increased by a maximum of 0.17 (34%) over the baseline vertical tail. Active flow control effectiveness generally decreased with increasing sideslip angle. In the absence of a boundary layer trip, active flow control effectiveness was similar to that for the tripped case at lower rudder deflections, but superior at greater deflections. The relative importance of multiple flow control parameters was investigated. The total momentum coefficient was determined to be the more dominant factor than the blowing ratio. Synthetic jet actuator orifice aspect ratio and spacing between adjacent actuator orifice edges was also studied. Synthetic jets were shown to be a more effective flow control technique than passive vortex generators, demonstrating their potential in a full-scale application.