Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)
Technical Report,01 May 2012,30 Apr 2015
University Of Arizona Tucson United States
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The potential of thermal perturbations i.e. energy deposition and subsequent compression wave generation as a mechanism for high amplitude, high bandwidth actuation has been demonstrated, but the fundamental physics of how this influences the flow field remain poorly understood. The aim of this study is to establish knowledge of the fundamental mechanisms underpinning the success of energy deposition for active flow control. The basic nature of this problem requires examination of a canonical flow system and turbulent shear layers are employed due to their ubiquitous nature inactive flow control. The effects of localized thermal perturbations, delivered by electrical discharges and pulsed lasers, on these flows are studied experimentally with strong consideration of the rapidly developing literature and established theory. Our most important finding is that the required energy deposition is related to an as yet to be determined measure of the initial shear layer thickness. The initial shear layer state and free stream velocity are of secondary importance in the flow regimes surveyed. This suggests that amplitude scaling ideas for thermal perturbations are fundamentally different from those accepted for momentum-based devices. It also provides guidance for moving forward with such a definition.