A Numerical Method of Calculating the Boundary-induced Interference in Slotted of Perforated Wind Tunnels of Rectangular Cross Section


Book Description

A numerical method is presented for calculating the boundary-induced interference at subsonic speeds in wind tunnels of rectangular cross section with slotted or perforated walls. The slot width or wall porosity can vary throughout the test section. The interference can be computed at any point in the test section. The model can be any configuration and can be located anywhere in the test section. Several examples are given, and comparison is made with other methods were available.




NASA Technical Note


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Approximate Treatment of V/STOL Wall Interference for Closed Circular Tunnels


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An approximate treatment of V/STOL wall interference in a circular tunnel indicates that the interference factors at the model for this tunnel should be of the same order of magnitude as those presently available for a square tunnel of equal cross-sectional area. There is a greater degree of uncertainty with respect to the lateral and longitudinal distributions of interference; however, the available results for the square tunnel should be reasonably close to those of the circular tunnel provided that the model is relatively small in comparison with the test section.




Method of Calculating the Wind Tunnel Interference for Steady and Oscillating Wings in Tunnels of Arbitrary Wall Configuration


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A method of calculating the wind tunnel interference induced by arbitrary wall configurations has been developed wherein a linearized equation of the perturbation velocity potential is used to describe the flow in the tunnel. A series solution of the interference velocity potential satisfies the differential equation exactly. The constant coefficients in the series solution are determined by the point matching technique along the boundary. Results are presented for slotted tunnel walls with homogeneous boundary conditions. Solutions presented show excellent agreement with the results obtained by other methods for a stationary as well as an oscillating wing. Finally, the method is applied to compute a set of zero interference configurations for a combination of slot openings of side walls, roof, and floor. (Author).







Low-Speed Wind Tunnel Testing


Book Description

A brand-new edition of the classic guide on low-speed wind tunnel testing While great advances in theoretical and computational methods have been made in recent years, low-speed wind tunnel testing remains essential for obtaining the full range of data needed to guide detailed design decisions for many practical engineering problems. This long-awaited Third Edition of William H. Rae, Jr.'s landmark reference brings together essential information on all aspects of low-speed wind tunnel design, analysis, testing, and instrumentation in one easy-to-use resource. Written by authors who are among the most respected wind tunnel engineers in the world, this edition has been updated to address current topics and applications, and includes coverage of digital electronics, new instrumentation, video and photographic methods, pressure-sensitive paint, and liquid crystal-based measurement methods. The book is organized for quick access to topics of interest, and examines basic test techniques and objectives of modeling and testing aircraft designs in low-speed wind tunnels, as well as applications to fluid motion analysis, automobiles, marine vessels, buildings, bridges, and other structures subject to wind loading. Supplemented with real-world examples throughout, Low-Speed Wind Tunnel Testing, Third Edition is an indispensable resource for aerospace engineering students and professionals, engineers and researchers in the automotive industries, wind tunnel designers, architects, and others who need to get the most from low-speed wind tunnel technology and experiments in their work.




Approximation of the Spanwise Distribution of Wind-tunnel-boundary Interference on Lift of Wings in Rectangular Perforated-wall Test Sections


Book Description

An approximation method has been developed for calculating the spanwise distribution of wind-tunnel-boundary upwash interference on lift of wings in rectangular perforated-wall test sections. This method is applied to square test sections with an assumed effective permeability constant of 0.6. A problem of considerable difficulty in practical application of the method presented is the estimation of an effective permeability constant. Because of the variation of the upwash interference with Mach number and of the influence of boundary layer on the effective permeability factor, the boundary interference in a perforated-wall wind-tunnel test section at high subsonic Mach numbers is likely to be of the nature of that in an open-throat tunnel.




NASA Scientific and Technical Reports


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