Accession Number : ADA330174

Title :   Combined Theoretical and Experimental Study of Phenomena Related to Limit Cycle Oscillations.

Descriptive Note : Final rept. Jun 93-May 97,

Corporate Author : LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS

Personal Author(s) : Walker, J. D. ; Smith, C. R. ; Delph, T.

PDF Url : ADA330174

Report Date : 13 OCT 1997

Pagination or Media Count : 9

Abstract : A combined theoretical, computational, and experimental program has investigated situations where fluid motion and a flexible surface produce nonlinear interactions. The main cases of interest concern situations where an external flow field contains a significant disturbance, such as a vortex in subsonic flow or a shock wave in supersonic flow. This type of flow feature can produce pressure perturbations which may provoke movement in flexible panels on the surface, as well as unsteady viscous separation effects in the boundary layers, which are on all solid walls. The net result is a complex interaction between the external mainstream flow, the viscous boundary layers, and the flexible surface itself The aforementioned interactions produce complicated oscillations of the surface that are sometimes refereed to as limit cycle oscillations (LCO). When such events are observed, it is common for a significant flow disturbance, such as a shock wave or vortex, to be somewhere in the vicinity. The present research addresses a number of fundamental problems of LCO, with the goal of establishing cause and effect relationships in relatively simple environments. Several computational and experimental studies of selected simplified interactions are described in the body of the report.

Descriptors :   *SUBSONIC FLOW, *SUPERSONIC FLOW, *OSCILLATION, EXPERIMENTAL DATA, SHOCK WAVES, EDDIES(FLUID MECHANICS), TRAILING VORTICES, PERTURBATIONS, BAROMETRIC PRESSURE, AIR WATER INTERACTIONS, LAMINAR FLOW, INSTABILITY, BOUNDARY LAYER FLOW, LASER VELOCIMETERS.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE