Accession Number : ADA336654

Title :   Velocity Profiles and Skin Friction on a Ribletted Flat Plate in Adverse Pressure Gradient.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH

Personal Author(s) : Branam, Richard D.

PDF Url : ADA336654

Report Date : DEC 1997

Pagination or Media Count : 179

Abstract : This project investigated the flow field characteristics over a flat, ribletted plate and the effects of an adverse pressure gradient on this flow field. Testing examined the development of the flow over the ribletted plate from laminar through fully turbulent flow fields. The flow field states (laminar, transitional, and turbulent) were determined using local turbulence intensity values and boundary layer profiles. Several parameters were examined to help better describe the flow characteristics, boundary layer profiles, and influence on skin friction drag. The skin friction drag coefficients were calculated using a numerical integration technique to determine an average value and scaled to the platform area of the plate to compare results with smooth plate values. Although the geometry and flow conditions produced a drag augmenting case, skin friction followed trends described by the other flow parameters; streamwise velocity, Reynolds stress, etc. At locations where the boundary layer developed in the riblet valley, the skin friction was higher. As the flow developed to transitional and fully turbulent, higher values were also experienced. For the zero pressure gradient and mild adverse pressure gradient, counter rotating vortices developed in the riblet valley. This more organized motion also had slightly reduced skin friction below the transitional flow field for the plate as well.

Descriptors :   *VELOCITY, *PRESSURE GRADIENTS, *FLOW FIELDS, *SKIN FRICTION, STRESSES, PARAMETERS, INTENSITY, THESES, BOUNDARY LAYER, TURBULENCE, TURBULENT FLOW, VORTICES, REDUCTION, PROFILES, PLATFORMS, PLATES, COEFFICIENTS, NUMERICAL INTEGRATION, ADVERSE CONDITIONS, TRANSITIONS, NUMERICAL METHODS AND PROCEDURES, COUNTERROTATION, MOMENTUM TRANSFER.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE