Utilization of Schlieren Imaging to Investigate the Effect of Active Control on Multi-Aperture Rectangular Single Expansion Ramp Nozzle

Schlieren imaging is a well-known method to investigate and record a flow field’s structure. It is an invaluable tool to record the affect of an active control composed of micro-jets in the flow field of the shockwaves created by a Multi-Aperture Rectangular Single Expansion Ramp Nozzle (MARS). The Schlieren imaging system used is designed vertically around the MARS nozzle to accurately capture the developing shock structures. Previously, research was performed using a passive control which was proven to diminish a dominant frequency tone created from the instability at the interface of the core and bypass streams within the MARS. To expand and improve upon the past methods used, active control is implemented in the splitter plate trailing edge region, a region determined via simulation to be highly receptive to excitation. Schlieren imaging is used in order to record and understand the change resulting from the active control. By using this method, data from the active control can be compared to previous experiments that used a passive control as well as the uncontrolled case. The comparison of the data from the two control systems is extremely important to determine the effect of an active control on the restriction of the dominant frequency that arises in the flow field.