Accession Number : ADA131396

Title :   Wind Tunnel Wall Interference.

Descriptive Note : Final rept. 1 Apr 77-31 Mar 82,


Personal Author(s) : Bliss,D B

PDF Url : ADA131396

Report Date : Apr 1983

Pagination or Media Count : 20

Abstract : The aerodynamic behavior of an isolated finite length slender slot in a wind tunnel wall was analyzed. Numerical and analytical solutions were obtained relating the pressure differential to the average flow rate through the slot as a function of slot geometry for subsonic and supersonic flow. These solutions apply to the cases of linear and quadratic behavior corresponding to small and large slot flow rates. The analysis was extended to include the effect of an imposed pressure gradient along was extended to include the effect of an imposed pressure gradient along the slot. The results obtained are applicable to low aspect ratio holes as well as slots, and thus provide insight into the behavior of both slotted and perforated walls. The pressure gradient effect on holes was found to introduce a pressure tunnel walls. The effect of aerodynamic interference between holes in a perforated wall was studied for two- and three-dimensional configuration using a wavy wall model problem. It was found that the interference effect between wall elements is relatively local over a wide range of parameters, thereby allowing it to be represented by an additional term in the average wall boundary condition. The interference effect takes the form of a streamline curvature term. The concept of a compliant wall wind tunnel was explored by analysis of a model problem to demonstrate a particular flexible wall concept. In the area of adaptive wall winds tunnels, a method was developed which shows how control adjustments should be made to converge very rapidly to interference-free conditions.

Descriptors :   *Wind tunnels, *Subsonic flow, *Supersonic flow, *Walls, Interference, Slots, Porous materials, Perforation, Deformation, Adaptive systems, Flexible materials, Pressure gradients, Flow rate, Aspect ratio, Holes(Openings), Boundaries, Control systems, Transonic flow, Aerodynamic characteristics, Mathematical models

Subject Categories : Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE