Accession Number : ADA321557

Title :   Some Structural Features of a Turbulent Wing-Body Junction Vortical Flow.

Descriptive Note : Technical rept. 1 Jan-30 Sep 96,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCE AN ENGINEERING

Personal Author(s) : Olcmen, M. S. ; Simpson, R. L.

PDF Url : ADA321557

Report Date : 30 SEP 1996

Pagination or Media Count : 111

Abstract : The horse-shoe vortex that forms around a wing-wall junction is experimentally investigated. Laser-Doppler velocimeter measurements of mean velocity and higher order statistics including the third order products are reported for 15 measurement stations in one plane to the side of the junction of a 3:2 elliptical nose, NACA 0020 tail wing and a wall. The approach Reynolds number of the air flow based on momentum thickness is approximately 5940. The outer layer vortical structure on the down-wash or wing side results in a thin boundary layer and lower turbulence intensity due to the redirected free-stream. Lateral pressure-gradients cause separation on the uplifting side of the vortex on the wall. Bimodal histograms of the w fluctuating velocity occur under the vortex core near the wall. A vortical structure with higher vorticity concentration and opposite sense to the large vortical structure is located below the large vortical structure. High normal stress values are obtained at the wing-wall junction. In this wing-wall junction region a vortical structure of the same rotation sense of the large outer layer vortex forms. Triple products describe the diffusion processes for this type of a flow. In such a flow the shear-stress angle (SSA) highly lags the flow-gradient angle (FGA) and the turbulent structure highly lags the mean flow. The turbulence diffusion is highly altered due to the presence of the large outer layer vortical structure.

Descriptors :   *TURBULENT FLOW, *VORTICES, *WING BODY CONFIGURATIONS, PRESSURE GRADIENTS, AIR FLOW, TURBULENCE, FLOW FIELDS, SHEAR STRESSES, ORDER STATISTICS, FREE STREAM, AERODYNAMIC LIFT, REYNOLDS NUMBER, BOUNDARY LAYER FLOW, LASER VELOCIMETERS, THREE DIMENSIONAL FLOW, TURBULENT DIFFUSION.

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE