Separated Turbulent Shear Layer Modification Via Feedback Flow Control and Feedback Flow Control with Experiment Based Order Reduction

摘要

Losses in the performance and effectiveness of optical systems are caused by turbulence. In particular, separated turbulent flow phenomena are present in several aero-optics applications. In an effort to reduce the adverse effects of turbulence, we are exploring the use of both open and closed-loop flow control. A series of experiments were performed in Syracuse University and Wright-Patterson Air Force Base (WPAFB) facilities using two test models, a quarter- and half-scale, respectively. The 3D turrets contained an actuation system that consists of 11 to 17 synthetic jets placed upstream from the leading edge of the aperture. Different actuation cases were tested to then evaluate the effects of the flow control over the aperture area and their control authority. Simultaneous surface pressure and particle image velocimetry (PIV) measurements in the separated region were performed, both with and without flow control. The PIV results for the Syracuse test suggest that with the open-loop control the separation zone above the aperture is reduced spatially and the mean square velocity fluctuations reduced in amplitude by 15 to 20 percent. Pressure results from the closed loop test at WPAFB present a 20 percent reduction in the amplitude when compared to the open loop results.