Current Projects

Control of Supersonic Impinging Jets

Supersonic impinging jets, such as those occurring in the next generation short takeoff and vertical landing (STOVL) aircraft, generate a highly oscillatory flow with high unsteady loads on the nearby structures and the landing surfaces. These high-pressure and acoustic loads are also accompanied by a dramatic loss in lift during hover. Other adverse phenomenons include severe ground erosion on the landing surface and hot gas ingestion into the engine inlets. It is now well known that the highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields, which leads to these adverse effects.

Flowfield around a STOVL aircraft

The current project at the STOVL facility, sponsored by Air Force Office of Scientific Research (AFOSR), is to characterize the impinging jets and eliminate unwanted effects of impinging jet flows. We have demonstrated that arrays of microjets, appropriately placed near the nozzle exit, effectively disrupt the feedback loop, thus reducing the related undesired effects. It has also been demonstrated that an active control strategy using pulsed microjets modifies the flowfield and show uniform reduction of unsteady loads over a wide range of operating conditions. We are presently studying the characteristics of heated impinging jets and its control using supersonic microjets.

Turbulence Intensity without and with control