Accession Number : ADA322460

Title :   Numerical and Experimental Investigation of the Flowfield Near a Wrap-Around Fin.

Descriptive Note : Doctoral thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Tilmann, Carl P.

PDF Url : ADA322460

Report Date : MAR 1997

Pagination or Media Count : 150

Abstract : A wall-mounted semi-cylindrical model fitted with a single wrap-around fin (WAF) has been investigated both numerically and experimentally, with the objective of characterizing the mean and turbulent flowfield in the vicinity of the fin. Numerical and experimental results are used to determine the nature of the flowfield and quantify the effects of fin curvature on the character of the flow near WAFs. This research has been motivated by the need to identify possible sources of a rolling moment reversal observed at high speeds in sub-scale flight tests. Detailed mean flow and turbulence measurements were obtained in the AFIT Mach 3 wind tunnel using conventional probes and cross wire hot film anemometry at a series of stations upstream of and aft of the fin shock/boundary layer interaction. Hot film anemometry results showed the turbulence intensity in the fuselage boundary layer to be far greater on the concave side of the fin than on the convex side. Similarly, the Reynolds shear stress rises dramatically on the concave side of the fin and is reduced on the convex side. These results are consistent with the stabilizing and destabilizing effects of pressure gradient distortion on supersonic boundary layers. Mean flow was also obtained in the AFIT Mach 5 wind tunnel using conventional pressure probes. Shadowgraph and schlieren photography were used for flow visualization in both wind tunnels.

Descriptors :   *GUIDED MISSILES, *NUMERICAL ANALYSIS, *FLOW FIELDS, *SUBMUNITIONS, *FINS, STRESSES, PRESSURE GRADIENTS, STATIONS, FLIGHT TESTING, MEASUREMENT, PROBES, ROLL, EXPERIMENTAL DATA, SCALE MODELS, HIGH VELOCITY, INTENSITY, FILMS, BOUNDARY LAYER, TURBULENCE, TURBULENT FLOW, MOMENTS, FLOW VISUALIZATION, PRESSURE MEASUREMENT, CURVATURE, REVERSIBLE, SHEAR STRESSES, FUSELAGES, FLOW, MEAN, SUPERSONIC CHARACTERISTICS, DISTORTION, WIND TUNNELS, ANEMOMETERS, SCHLIEREN PHOTOGRAPHY, MOMENTUM TRANSFER, SPARK SHADOWGRAPH PHOTOGRAPHY, CONCAVE BODIES, CONVEX BODIES, TUBE LAUNCHED.

Subject Categories : Guided Missile Dynam, Config & Cntrl Surfaces
      Ammunition and Explosives
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE