Using Active Flow Control to Improve the Capabilities of a Tilt Wing Tilt Rotor Aircraft

Abstract

This thesis covers wind tunnel experiments on a scale model of a V22 starboard wing. The wing had been used in previous experiments but was modified to incorporate a suction/blowing system at the leading edge. The model used a simple flap that was 3D printed with 28 sweeping jet actuators with a throat area of 0.025in2. Along with leading edge suction and blowing, the leading edge could be replaced with a 3D printed piece that had 30 actuators. Many experiments in the past looked at reducing the download on VTOL aircraft using multiple different active flow control techniques. The experiments covered in this thesis utilized different combinations of sweeping jet actuators over the flap and leading edge, leading edge steady blowing, leading edge suction, and a Krueger flap. Data was taken for an alpha range of -50˚ to -104˚ in 2˚ intervals and the range of flap deflections tested was 45˚ to 75˚ in 5˚ intervals. The experiments focused on the download, suck back force, and pitching moment acting on the wing. For the VTOL configuration, sweeping jet actuators operating with a Cμ of 1.50% delayed separation over the flap, allowing for larger flap deflections to be utilized during hover. This decreased the download by about 11% with the potential for larger download reductions with higher flap deflections and Cμ values. This configuration increased the nose down pitching moment and substantially increases the suck back force. Including leading edge suction with a flow rate comparable to that of the sweeping jet actuators reduced the download by about 21% compared to the VTOL baseline. This also decreased the nose down pitching moment by 8% while only increasing the suck back force by 14%. Adding a Krueger with sweeping jet actuators at the leading edge produced download results comparable to the configurations with sweeping jet actuators over the flap. The major difference was that it generated a suck forward instead of suck back force and decreased the nose down pitching moment by about 40% compared to the baseline. Changing this vehicle from a VTOL configuration to a STO configuration by tilting the rotors forward decreased the download by close to 17% without the need for any active flow control. Including active flow control at a Cμ of 1.50% reduced the download by 30% compared to the VTOL baseline configuration. One problem with the tilt rotor configuration is that there is a large increase in the nose down pitching moment. More experiments on a model of the full aircraft is needed to figure out how to compensate for the increased pitching moment.