Suction and Oscillatory Blowing Interaction with Boundary Layers

Abstract

This work presents ongoing experiments toward developing fundamental understanding of suction and oscillatory blowing (SaOB) flow control mechanisms along with development of accurate and practical CFD simulation methodologies for complex unsteady active flow control systems. Experimental and computational studies were conducted on SaOB actuators’ internal flow and external interaction with two zero pressure gradient boundary layers. The experimental work incorporates detailed multi component hot-wire measurements of both laminar and turbulent boundary layers with steady suction and pulsed blowing for a single actuator and an array configuration. Large eddy simulation was employed for the computational model. Simulations were carried out on the actuator internal flow, and the resulting oscillatory blowing jet exit velocity profiles are characterized and fit with a functional form, in order to create simplified boundary conditions for future flow control simulations. Both experimental and computational results show that the suction hole geometry and configuration is an important factor in determining the structure and stability of the downstream laminar as well as turbulent boundary layer flow-fields. Measurements of oscillatory blowing jets interacting with a turbulent boundary layer demonstrate this flow control produces unsteady spanwise and streamwise vorticity components that can be interpreted as counter-rotating streamwise vortex patterns.