W. G. Pritchard Lab Seminar: 4-5 PM, 116 McAllister Building

	       **Tuesday February 26, 2002**
	
Micro-Active Control of a Jet Flow

Thomas Peacock

Fluid Dynamics Laboratory
Department of Mathematics
Massachusetts Institute of Technology

Abstract:

We present the results of a combined experimental and numerical study
in which MEMS micro-actuators are used to control the instabilities
of a jet flow. The system is unstable to two different modes and we
are able to use the actuators to selectively excite either mode. The
experimental growth rates of the instabilities are compared with
numerical calculations, taking into account the non-parallel nature
of the jet. These small scale disturbances are then amplified by the
flow and give rise to large scale vortices that entrain air into the
jet. The vortices are responsible for the phenomena of `sensitive
flames', which was the subject of many striking experiments at the
start of the 20th century.