Accession Number : ADA322347

Title :   Experimental Investigation of Flow Control by Means of Airfoil Flapping.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Yue, Jiannwoei

PDF Url : ADA322347

Report Date : SEP 1996

Pagination or Media Count : 94

Abstract : Flapping airfoils generate thrust-producing jet-like wakes. It therefore is the objective of this investigation to explore whether this feature can be used for effective flow control. To this end, the flow characteristics of flapping airfoils are first explored in a water tunnel experiment, using dye flow visualization and laser-doppler velocimeter. The effect of airfoil flapping frequency and amplitude of oscillation and of flow velocity on the wake flow characteristics are determined. This is followed by a second water tunnel experiment, where a small flapping airfoil is mounted in and near the separated flow region caused by the flow over a backward-facing step. The effect of airfoil size, location, frequency, and amplitude of oscillation on the separated flow region is again determined by means of laser-doppler velocimeter. It is found that the reattachment length of the separated flow region can be reduced by as much as 70%.

Descriptors :   *FLOW VISUALIZATION, *WAKE, *FLAPS(CONTROL SURFACES), THESES, TURBULENCE, VORTICES, FLOW FIELDS, FREE STREAM, FLOW SEPARATION, THRUST CONTROL, JET FLOW, REYNOLDS NUMBER, LASER VELOCIMETERS, WATER TUNNELS, THREE DIMENSIONAL FLOW.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE