Accession Number : ADA311422

Title :   The Forced Turbulent Wall Jet Effects of Pressure Gradient and Curvature.

Descriptive Note : Final rept. 16 Jan 93-15 Jan 96,

Corporate Author : ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING

Personal Author(s) : Wygnanski, Israel

PDF Url : ADA311422

Report Date : 01 JUN 1996

Pagination or Media Count : 45

Abstract : The studies completed in the period of the proposal were in three parts: (1) Both hot wire and PIV data have been obtained on the Coanda cylinder. Strong influences of curvature and of the pressure gradient on the mean and the turbulence quantities were found. New structures were observed around the cylinder in the forced case. A theoretical model was established for the mean flow, which will be an important tool in the further stability studies. (2) Two types of weak wall jet have been observed. Length and velocity scales were found and applied in successful normalization of the mean velocity profiles. Furthermore, three instability modes, coupled to each other, were investigated through forcing. (3) A novel technique for identification of coherent motions was developed which can eliminate the influence of phase jitter and discover much more coherent energy than the conventional phase locked ensemble averaging technique, based on which a reasonable coherent energy budget was established for the first time. This technique will be applied to explore the role of coherent motion in the control of separation.

Descriptors :   *TURBULENT FLOW, PRESSURE GRADIENTS, MATHEMATICAL MODELS, STRESS ANALYSIS, AERODYNAMIC STABILITY, TURBULENCE, VORTICES, COMPUTATIONAL FLUID DYNAMICS, FLOW FIELDS, CYLINDRICAL BODIES, AERODYNAMIC DRAG, DATA ACQUISITION, FLAPS(CONTROL SURFACES), VELOCIMETERS, FLOW SEPARATION, PRESSURE DISTRIBUTION, AERODYNAMIC LIFT, JET FLOW, REYNOLDS NUMBER, SKIN FRICTION, HOT WIRE ANEMOMETERS, SHEAR FLOW, BOUNDARY LAYER FLOW.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE