142 Matching Results

Search Results

Advanced search parameters have been applied.

Boundary-induced upwash for yawed and swept-back wings in closed circular wind tunnels

Description: Report presenting a determination of the tunnel-induced velocities for yawed and swept-back airfoils in a closed circular wind tunnel. Calculations were performed for elemental horseshoe vortices with one tip of the bound vortex on the tunnel axis for a range of yaw angles and bound-vortex lengths.
Date: May 1947
Creator: Eisenstadt, Bertram J.
Partner: UNT Libraries Government Documents Department

The effect of the walls in closed type wind tunnels

Description: "A series of tests has been conducted during the period 1925-1927 by the National Advisory Committee for Aeronautics in the variable-density wind tunnel on several airfoil models of different sizes and sections to determine the effect of tunnel-wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical corrections give the best results, and their use is recommended for correcting closed wind tunnel results to the conditions of free air" (p. 375).
Date: 1928
Creator: Higgins, George J.
Partner: UNT Libraries Government Documents Department

The NACA CYH airfoil section

Description: The NACA CYH airfoil section is described and its aerodynamic characteristics are given as tested in the NACA variable density wind tunnel at twenty atmosphere pressure. This section has a low drag, a high maximum lift, and a small travel of center of pressure.
Date: June 1926
Creator: Higgins, George J.
Partner: UNT Libraries Government Documents Department

Wall interference in closed type wind tunnels

Description: "A series of tests has been conducted by the National Advisory Committee for Aeronautics, in the variable density wind tunnel on several airfoils of different sizes and sections to determine the effect of tunnel wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical correction gives the best results and its use is recommended for correcting closed wind tunnel results to conditions of free air" (p. 1).
Date: March 1927
Creator: Higgins, George J.
Partner: UNT Libraries Government Documents Department

High-speed wind tunnels

Description: Wind tunnel construction and design is discussed especially in relation to subsonic and supersonic speeds. Reynolds Numbers and the theory of compressible flows are also taken into consideration in designing new tunnels.
Date: November 1936
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department

Determination of boundary-layer transition Reynolds numbers by surface-temperature measurements of a 10 degree cone in various NACA supersonic wind tunnels

Description: Report presenting an investigation in several NACA wind tunnels to determine transition Reynolds numbers on a 10 degree cone at zero angle of attack. The trends of transition Reynolds number with stream Reynolds number and Mach number are not consistent across the different tunnels. These inconsistencies are attributed to variations in free-stream turbulence, flow irregularities introduced by compressor systems, and other airstream disturbances like compression- or expansion-wave boundary-layer interactions.
Date: October 1953
Creator: Ross, Albert O.
Partner: UNT Libraries Government Documents Department

The development and performance of two small tunnels capable of intermittent operation at Mach numbers between 0.4 and 4.0

Description: Report presenting the design, development, and performance of equipment suitable for use by educational institutions for student training and basic compressible-flow research. Supersonic nozzles designed for a range of Mach numbers were tested in the blowdown tunnel and produced average Mach numbers close to the design values.
Date: September 1950
Creator: Lindsey, Walter F. & Chew, William L.
Partner: UNT Libraries Government Documents Department

Experimental investigation of two-dimensional tunnel-wall interference at high subsonic speeds

Description: Report presenting a determination of the tunnel-wall interference for a two-dimensional-flow, rectangular, closed-throat wind tunnel over a range of Mach numbers. Aerodynamic data obtained showed that the influence of the walls becomes progressively greater with increasing Mach number and increasing chord-height ratio.
Date: December 1953
Creator: Knechtel, Earl D.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of a technique of producing a heated core in a supersonic wind-tunnel stream

Description: Report presenting an investigation at Mach numbers 1.9 and 3.0 to demonstrate that a central core of air of high stagnation temperature can be produced in the test section of a supersonic wind tunnel. This makes performing wind tunnel testing cheaper and controls for more variables. Results regarding the core studies at Mach number 1.9 and 3.0 and diffuser performance at Mach number 1.9 are provided.
Date: February 18, 1955
Creator: Rousso, Morris D. & Beheim, Milton A.
Partner: UNT Libraries Government Documents Department

Considerations on the effect of wind-tunnel walls on oscillating air forces for two-dimensional subsonic compressible flow

Description: This report treats the effect of wind-tunnel walls on the oscillating two-dimensional air forces in a compressible medium. The walls are simulated by the usual method of placing images at appropriate distances above and below the wing. An important result shown is that, for certain conditions of wing frequency, tunnel height, and Mach number, the tunnel and wing may form a resonant system so that the forces on the wing are greatly changed from the condition of no tunnel walls. It is pointed out that similar conditions exist for three-dimensional flow in circular and rectangular tunnels and apparently, within certain Mach number ranges, in tunnels of nonuniform cross section or even in open tunnels or jets.
Date: 1953
Creator: Runyan, Harry L. & Watkins, Charles E.
Partner: UNT Libraries Government Documents Department

Tests of the N.P.L. airship models in the variable density wind tunnel

Description: Report presenting testing in the variable density wind tunnel on two airship models known as the NPL Standardization Models, long and short. The resistance or shape coefficients were determined for each model through a range of Reynolds numbers. Further work is found to be necessary in the standardization of wind tunnels.
Date: September 1927
Creator: Higgins, George J.
Partner: UNT Libraries Government Documents Department

Jet-boundary corrections for reflection-plane models in rectangular wind tunnels

Description: A detailed method for determining the jet-boundary corrections for reflection-plane models in rectangular wind tunnels is presented. The method includes the determination of the tunnel span local distribution and the derivation of equations for the corrections to the angle of attack, the lift and drag coefficients, and the pitching-, rolling-, yawing-, and hinge-moment coefficients. The principle effects of aerodynamic induction and of the boundary-induced curvature of the streamlines have been considered. An example is included to illustrate the method. Numerical values of the more important corrections for reflection-plane models in 7 by 10-foot closed wind tunnels are presented.
Date: April 13, 1943
Creator: Swanson, Robert S. & Toll, Thomas A.
Partner: UNT Libraries Government Documents Department

Wind Tunnel Studies in Aerodynamic Phenomena at High Speed

Description: A great amount of research and experimental work has been done and fair success obtained in an effort to place airplane and propeller design upon an empirical basis. However, one can not fail to be impressed by the apparent lack of data available toward establishing flow phenomena upon a rational basis, such that they may be interpreted in terms of the laws of physics. With this end in view it was the object of the authors to design a wind tunnel differing from the usual type especially in regard to large power and speed of flow.
Date: 1921
Creator: Caldwell, F. W. & Fales, E. N.
Partner: UNT Libraries Government Documents Department

Instrumentation of the Ames Supersonic Free-Flight Wind Tunnel

Description: Memorandum presenting a description of the equipment used in the Ames supersonic free-flight wind tunnel to obtain the data necessary to measure the aerodynamic characteristics of free-flying models. The model is fired from a gun into the supersonic air stream of a blowdown-type wind tunnel. The action resulting from aerodynamic forces is computed from a time-distance-attitude record of the model flight through the test section.
Date: April 24, 1952
Creator: Briggs, Robert O.; Kerwin, William J. & Schmidt, Stanley F.
Partner: UNT Libraries Government Documents Department

The Ames Supersonic Free-Flight Wind Tunnel

Description: Memorandum presenting a description of the Ames supersonic free-flight wind tunnel, which is a new piece of equipment for aerodynamic research at high supersonic Mach numbers. It has a wide Mach number range extending from low supersonic speeds to Mach numbers in excess of 10. The air stream in the tunnel is imperfect, mainly due to a symmetrical pair of oblique shock waves which reflect down the test section.
Date: April 25, 1952
Creator: Seiff, Alvin; James, Carlton S.; Canning, Thomas N. & Boissevain, Alfred G.
Partner: UNT Libraries Government Documents Department

Tests of Six Symmetrical Airfoils in the Variable Density Wind Tunnel

Description: "This paper is the first of a series covering an investigation of a family of airfoils all formed from a basic profile. It gives in preliminary form the results of six symmetrical airfoils, differing only in maximum thickness. The maximum thickness-to-chord ratios are 0.06, 0.09, 0.12, 0.15, 0.18, and 0.21" (p. 1).
Date: July 1931
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

The Theory of Wind-Tunnel Wall Interference

Description: This report outlines the development of a general theory for the calculation of the effect of the boundaries of the air stream on the flow past an airfoil. Analytical treatments are given for tunnels with horizontal boundaries only, with vertical boundaries only, and with a bottom boundary only. Formulas are developed for the tunnel wall interference in each case for an airfoil located at the center of the tunnel. The correction is given as a function of the width to height ratio of the tunnel.
Date: October 9, 1931
Creator: Theodorsen, Theodore
Partner: UNT Libraries Government Documents Department