Full-Scale Flight Demonstration of Active Control of a Pod Wake

Abstract

Pods and externally carried stores can generate unsteady flows in their wakes with high acoustic loads capable of damaging aircraft structure. Active flow control technology has the potential to modify unsteady shedding in the wake of the pod, thereby reducing acoustic loads. In this work, an active flow control system was developed and tested on an F16 Aircraft. Using open loop flow control actuation, the frequency of the acoustic loads can be modified and their amplitude reduced. In addition, wake location can also be manipulated by the active control system. During the development process, small, mid, and full-scale wind tunnel tests were conducted with synthetic jet flow control actuators. Wind tunnel tests leading up to the flight test were conducted from Mach numbers from 0.2 up to 0.85. Synthetic jet exit velocities in excess of 800 feet per second were achieved. As was the case for wind tunnel pod wake control tests, the frequency of shedding was controlled, the location of the wake also was controlled, and the amplitude of the pressure fluctuations was reduced during the flight tests. Full-scale flight data were obtained for various actuator frequencies and aircraft flight conditions such as speed, altitude, angle-of-attack and yaw angle.