Control of jets in crossflow

Air Force Office of Scientific Research         Graduate Student: Rajes Sau

 

                  

Direct numerical simulation is being used to develop control strategies that improve the mixing properties of jets in crossflow. Presently simulations are being performed to explain and scale experimental observations on the use of pulsing as a means of control. Since pulsing generates vortex rings, the mixing properties of vortex rings in the presence and absence of crossflow have been studied. It is shown, that in the absence of any crossflow, entrainment is highest when the stroke ratio equals the 'formation number'. However the presence of crossflow changes the formation number, and furthermore increases the entrainment by the trailing column (figure on right). Entrainment is therefore higher at stroke ratios greater than the formation number. The papers below propose physical mechanisms for this behavior. The figure on the left shows rate of volume change of scalar carrying fluid as a a function of stroke, in the presence (triangles), and absence (circles) of crossflow.

Publications

 

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