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Methods of Visually Determining the Air Flow Around Airplanes

Description: "This report describes methods used by the National Advisory Committee for Aeronautics to study visually the air flow around airplanes. The use of streamers, oil and exhaust gas streaks, lampblack and kerosene, powdered materials, and kerosene smoke is briefly described. The generation and distribution of smoke from candles and from titanium tetrachloride are described in greater detail because they appear most advantageous for general application. Examples are included showing results of the various methods" (p. 1).
Date: July 1932
Creator: Gough, Melvin N. & Johnson, Ernest
Partner: UNT Libraries Government Documents Department

Pressure distribution over airfoils at high speeds

Description: This report deals with the pressure distribution over airfoils at high speeds, and describes an extension of an investigation of the aerodynamic characteristics of certain airfoils which was presented in NACA Technical Report no. 207. The results presented in report no. 207 have been confirmed and extended to higher speeds through a more extensive and systematic series of tests. Observations were also made of the air flow near the surface of the airfoils, and the large changes in lift coefficients were shown to be associated with a sudden breaking away of the flow from the upper surface. The tests were made on models of 1-inch chord and comparison with the earlier measurements on models of 3-inch chord shows that the sudden change in the lift coefficient is due to compressibility and not to a change in the Reynolds number. The Reynolds number still has a large effect, however, on the drag coefficient. The pressure distribution observations furnish the propeller designer with data on the load distribution at high speeds, and also give a better picture of the air-flow changes.
Date: 1927
Creator: Briggs, L. J. & Dryden, H. L.
Partner: UNT Libraries Government Documents Department

The Nature of Air Flow About the Tail of an Airplane in a Spin

Description: "Air flow about the fuselage and empennage during a high-angle-of-attack spin was made visible in flight by means of titanium-tetrachloride smoke and was photographed with a motion-picture camera. The angular relation of the direction of the smoke streamer to the airplane axes was computed and compared with the angular direction of the motion in space derived from instrument measurement of the spin of the airplane for a nearly identical mass distribution. The results showed that the fin and upper part of the rudder were almost completely surrounded by dead air, which would render them inoperative; that the flow around the lower portion of the rudder and the fuselage was nonturbulent; and that air flowing past the cockpit in a high-angle-of-attack spin could not subsequently flow around control surfaces" (p. 1).
Date: May 1932
Creator: Scudder, N. F. & Miller, M. P.
Partner: UNT Libraries Government Documents Department

Effects of rocket-armament exhaust gas on the performance of a supersonic-inlet J34-turbojet-engine installation at Mach 2.0

Description: Report presenting an investigation of the effects of rocket-armament-exhaust-gas ingestion on the performance of a supersonic-inlet J34-turbojet-engine installation at Mach 2. Rockets were fired from two different spike positions and with the engine at high or low speed. Results regarding engine air flow, temperature, and flame-out are provided.
Date: February 20, 1956
Creator: Beheim, Milton A. & Evans, Phillip J.
Partner: UNT Libraries Government Documents Department

Effects of a J34 Turbojet Engine on Supersonic Diffuser Performance

Description: Report presenting testing of a translating cone inlet with a variable bypass at Mach numbers 1.6, 1.8, and 2.0 with both a choked exit plug and a J34 turbojet engine. The main difference between the two options was increased inlet subcritical stability with the engine. Results regarding basic diffuser performance, inlet stability, buzz amplitude and frequency, and diffuser-exit profiles are provided.
Date: January 4, 1956
Creator: Beheim, Milton A. & Englert, Gerald W.
Partner: UNT Libraries Government Documents Department

The Resistance to Air Flow of Porous Materials Suitable for Boundary-Layer-Control Applications Using Area Suction

Description: "Measurements were made of the resistance to air flow of commercially available porous materials. Three general types of porous media were tested - granular (sintered materials), fibrous (felt cloths and filter papers), and perforated. The flow-resistance characteristics of the porous materials tested are presented in a form intended to assist in the selection of materials for applications to boundary-layer control using area suction" (p. 1).
Date: January 1954
Creator: Dannenberg, Robert E.; Weiberg, James A. & Gambucci, Bruno J.
Partner: UNT Libraries Government Documents Department

Using SPARK as a Solver for Modelica

Description: Modelica is an object-oriented acausal modeling language that is well positioned to become a de-facto standard for expressing models of complex physical systems. To simulate a model expressed in Modelica, it needs to be translated into executable code. For generating run-time efficient code, such a translation needs to employ algebraic formula manipulations. As the SPARK solver has been shown to be competitive for generating such code but currently cannot be used with the Modelica language, we report in this paper how SPARK's symbolic and numerical algorithms can be implemented in OpenModelica, an open-source implementation of a Modelica modeling and simulation environment. We also report benchmark results that show that for our air flow network simulation benchmark, the SPARK solver is competitive with Dymola, which is believed to provide the best solver for Modelica.
Date: June 30, 2008
Creator: Wetter, Michael; Wetter, Michael; Haves, Philip; Moshier, Michael A. & Sowell, Edward F.
Partner: UNT Libraries Government Documents Department

Two-dimensional subsonic compressible flows past arbitrary bodies by the variational method

Description: Instead of solving the nonlinear differential equation which governs the compressible flow, an approximate method of solution by means of the variational method is used. The general problem of steady irrotational flow past an arbitrary body is formulated. Two examples were carried out, namely, the flow past a circular cylinder and the flow past a thin curved surface. The variational method yields results of velocity and pressure distributions which compare excellently with those found by existing methods. These results indicate that the variational method will yield good approximate solution for flow past both thick and thin bodies at both high and low Mach numbers.
Date: March 1951
Creator: Wang, Chi-Teh
Partner: UNT Libraries Government Documents Department

Design of Injectors for Low-Pressure Air Flow

Description: Report issued by the Bureau of Mines discussing the design of low-pressure injectors. As stated in the scope of paper, "this paper purposes to present and discuss methods of designing injectors for low-pressure air flow according to Professor Week's theory, with special reference to their use in mine and tunnel ventilation" (p. 1). This report includes tables, and illustrations.
Date: 1945
Creator: McElroy, G. E.
Partner: UNT Libraries Government Documents Department

The 7 by 10 foot wind tunnel of the National Advisory Committee for Aeronautics

Description: This report presents a description of the 7 by 10 foot wind tunnel and associated apparatus of the National Advisory Committee for Aeronautics. Included also are calibration test results and characteristic test data of both static force tests and autorotation tests made in the tunnel.
Date: October 22, 1931
Creator: Harris, Thomas A.
Partner: UNT Libraries Government Documents Department

Considerations of air flow in combustion chambers of high-speed compression-ignition engines

Description: The air flow in combustion chambers is divided into three fundamental classes - induced, forced, and residual. A generalized resume is given of the present status of air flow investigations and of the work done at this and other laboratories to determine the direction and velocity of air movement in auxiliary and integral combustion chambers. The effects of air flow on engine performance are mentioned to show that although air flow improves the combustion efficiency, considerable induction, friction, and thermal losses must be guarded against.
Date: April 1932
Creator: Spanogle, J. A. & Moore, C. S.
Partner: UNT Libraries Government Documents Department

Comparison of Two-Dimensional Air Flows About an NACA 0012 Airfoil of 1-Inch Chord at Zero Lift in Open and Closed 3-Inch Jets and Corrections for Jet-Boundary Interference

Description: Note presenting pressure distributions and schileren photographs for the high-speed flow about a symmetrical airfoil at zero lift in open and closed jets in order to show the nature of the jet-boundary interference. Results regarding the application of jet-boundary-interference theory, analysis of experimental wall-interference data and comparison with theory, conditions near choking, and change of velocity ratio with Mach number are provided.
Date: May 1946
Creator: Wright, Ray H. & Donaldson, Coleman duP.
Partner: UNT Libraries Government Documents Department

The Effect of Propeller Operation on the Air Flow in the Region of the Tail Plane for a Twin-Engine Tractor Monoplane

Description: Report presenting air-flow surveys made in the region of the tail plane of a typical twin-engine tractor monoplane model with tail surfaces removed. The surveys were made with propellers removed and operating and for both cases included the conditions for flaps retracted and flaps deflected 50 degrees.
Date: August 1942
Creator: Sweberg, Harold H.
Partner: UNT Libraries Government Documents Department

The Propeller and Cooling-Air-Flow Characteristics of a Twin-Engine Airplane Model Equipped With NACA D(Sub S)-Type Cowlings and With Propellers of NACA 16-Series Airfoil Sections

Description: Report presenting an investigation in the 19-foot pressure tunnel to determine the nacelle drag, the cowling-air flow, and the propeller characteristics of a model of a high-performance military airplane. The model is fitted with NACA D(sub S)-type engine cowlings and with propellers embodying NACA 16-series airfoil sections. Results regarding the propeller characteristics, drag and cowling-air flow with the propeller removed, the effect of propeller on flow through cowling, and the influence of cooling requirements on airplane performance are provided.
Date: September 1944
Creator: McHugh, James G. & Pepper, Edward
Partner: UNT Libraries Government Documents Department

Investigation of Air Flow in Open-Throat Wind Tunnels

Description: "Tests were conducted on the 6-inch wind tunnel of the National Advisory Committee for Aeronautics to form a part of a research on open-throat wind tunnels. The primary object of this part of the research was to study a type of air pulsation which has been encountered in open-throat tunnels, and to find the most satisfactory means of eliminating such pulsations. In order to do this it was necessary to study the effects of different variable on all of the important characteristics of the tunnel" (p. 399).
Date: September 26, 1928
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

Filter Media Recommendation Review

Description: The original filter recommended by PNNL for the RASA is somewhat difficult to dissolve and has been discontinued by the manufacturer (3M) because the manufacturing process (substrate blown microfiber, or SBMF) has been superceded by a simpler process (scrim-free blown microfiber, or BMF). Several new potential filters have been evaluated by PNNL and by an independent commercial lab. A superior product has been identified which provides higher trapping efficiency, higher air flow, is easier to dissolve, and is thinner, accommodating more filters per RASA roll. This filter is recommended for all ground-based sampling, and with additional mechanical support, it could be useful for airborne sampling, as well.
Date: January 7, 2002
Creator: Thompson, Robert C.; Miley, Harry S. & Arthur, Richard J.
Partner: UNT Libraries Government Documents Department

EXPERIMENTAL BUBBLE FORMATION IN A LARGE SCALE SYSTEM FOR NEWTONIAN AND NONNEWTONIAN FLUIDS

Description: The complexities of bubble formation in liquids increase as the system size increases, and a photographic study is presented here to provide some insight into the dynamics of bubble formation for large systems. Air was injected at the bottom of a 28 feet tall by 30 inch diameter column. Different fluids were subjected to different air flow rates at different fluid depths. The fluids were water and non-Newtonian, Bingham plastic fluids, which have yield stresses requiring an applied force to initiate movement, or shearing, of the fluid. Tests showed that bubble formation was significantly different in the two types of fluids. In water, a field of bubbles was formed, which consisted of numerous, distributed, 1/4 to 3/8 inch diameter bubbles. In the Bingham fluid, large bubbles of 6 to 12 inches in diameter were formed, which depended on the air flow rate. This paper provides comprehensive photographic results related to bubble formation in these fluids.
Date: June 26, 2008
Creator: Leishear, R & Michael Restivo, M
Partner: UNT Libraries Government Documents Department

Two-Dimensional Irrotational Transonic Flows of a Compressible Fluid

Description: The methods of NACA TN No. 995 have been slightly modified and extended in include flows with circulation by considering the alteration of the singularities of the incompressible solution due to the presence of the hypergeometric functions in the analytic continuation of the solution. It was found that for finite Mach numbers the only case in which the nature of the singularity can remain unchanged is for a ratio of specific heats equal to -1. From a study of two particular flows it seems that the effect of geometry cannot be neglected, and the conventional "pressure-correction" formulas are not valid, even in the subsonic region if the body is thick, especially if there is a supersonic region in the flow.
Date: June 1948
Creator: Kuo, Yung-Huai
Partner: UNT Libraries Government Documents Department

A model for simulating airflow and pollutant dispersion around buildings

Description: A three-dimensional, numerical mode1 for simulating airflow and pollutant dispersion around buildings is described. The model is based on an innovative finite element approach and fully implicit time integration techniques. Linear and nonlinear eddy viscosity/diffusivity submodels are provided for turbulence parameterization. Mode1 predictions for the flow-field and dispersion patterns around a surface-mounted cube are compared with measured data from laboratory experiments.
Date: February 24, 1999
Creator: Chan, S T & Lee, R L
Partner: UNT Libraries Government Documents Department