Technical Report Archive and Image Library (TRAIL) - 52 Matching Results

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Application of Radial-Equilibrium Condition to Axial-Flow Compressor and Turbine Design

Description: "Basic general equations governing the three-dimensional compressible flow of gas through a compressor or turbine are given in terms of total enthalpy, entropy, and velocity components of the gas. Two methods of solution are obtained for the simplified, steady axially symmetric flow; one involves the use of a number of successive planes normal to the axis of the machine and short distances apart, and the other involves only three stations for a stage in which an appropriate radial-flow path is used. Methods of calculation for the limiting cases of zero and infinite blade aspect ratios and an approximate method of calculation for finite blade aspect ratio are also given" (p. 1).
Date: January 1, 1949
Creator: Wu, Chung-Hua & Wolfenstein, Lincoln
Partner: UNT Libraries Government Documents Department

Characteristics of Low-Aspect-Ratio Wings at Supercritical Mach Numbers

Description: The separation of the flow over wings precipitated by the compression shock that forms as speeds are increased into the supercritical Mach number range has imposed serious difficulties in the improvement of aircraft performance. Three difficulties rise principally as a consequence of the rapid drag rise and the loss of lift that causes serious stability changes when the wing shock-stalls. Favorable relieving effects due to the three-dimensional flow around the tips were obtained and these effects were of such magnitude that it is indicated that low-aspect-ratio wings offer a possible solution of the problems encountered.
Date: January 1, 1949
Creator: Stack, John & Lindsey, W. F.
Partner: UNT Libraries Government Documents Department

Constant-pressure combustion charts including effects of diluent addition

Description: Charts are presented for the calculation of (a) the final temperatures and the temperature changes involved in constant-pressure combustion processes of air and in products of combustion of air and hydrocarbon fuels, and (b) the quantity of hydrocarbon fuels required in order to attain a specified combustion temperature when water, alcohol, water-alcohol mixtures, liquid ammonia, liquid carbon dioxide, liquid nitrogen, liquid oxygen, or their mixtures are added to air as diluents or refrigerants. The ideal combustion process and combustion with incomplete heat release from the primary fuel and from combustible diluents are considered. The effect of preheating the mixture of air and diluents and the effect of an initial water-vapor content in the combustion air on the required fuel quantity are also included. The charts are applicable only to processes in which the final mixture is leaner than stoichiometric and at temperatures where dissociation is unimportant. A chart is also included to permit the calculation of the stoichiometric ratio of hydrocarbon fuel to air with diluent addition. The use of the charts is illustrated by numerical examples.
Date: 1949
Creator: Turner, L. Richard & Bogart, Donald
Partner: UNT Libraries Government Documents Department

The design of low-turbulence wind tunnels

Description: From Summary: "Within the past 10 years there have been placed in operation in the United States four low-turbulence wind tunnels of moderate cross-sectional area and speed, one at the National Bureau of Standards, two at the NACA Langley Laboratory, and one at the NACA Ames Laboratory. This paper reviews briefly the state of knowledge and those features which make possible the attainment of low turbulence in wind tunnels. Specific applications to two wind tunnels are described."
Date: 1949
Creator: Dryden, Hugh L. & Abbott, Ira H.
Partner: UNT Libraries Government Documents Department

The development of cambered airfoil sections having favorable lift characteristics at supercritical Mach numbers

Description: Several groups of new airfoil sections, designated as the NACA 8-series, are derived analytically to have lift characteristics at supercritical Mach numbers which are favorable in the sense that the abrupt loss of lift, characteristic of the usual airfoil section at Mach numbers above the critical, is avoided. Aerodynamic characteristics determined from two-dimensional wind-tunnel tests at Mach numbers up to approximately 0.9 are presented for each of the derived airfoils. Comparisons are made between the characteristics of these airfoils and the corresponding characteristics of representative NACA 6-series airfoils.
Date: 1949
Creator: Graham, Donald J.
Partner: UNT Libraries Government Documents Department

Effect of Reynolds Number in Turbulent-Flow Range on Flame Speeds of Bunsen Burner Flames

Description: "The effect of flow conditions on the geometry of the turbulent Bunsen flame was investigated. Turbulent flame speed is defined in terms of flame geometry and data are presented showing the effect of Reynolds number of flow in the range of 3000 to 35,000 on flame speed for burner diameters from 1/4 to 1 1/8 inches and three fuels -- acetylene, ethylene, and propane. The normal flame speed of an explosive mixture was shown to be an important factor in determining its turbulent flame speed, and it was deduced from the data that turbulent flame speed is a function of both the Reynolds number of the turbulent flow in the burner tube and of the tube diameter" (p. 1).
Date: 1949
Creator: Bollinger, Lowell M. & Williams, David T.
Partner: UNT Libraries Government Documents Department

General Theory of Aerodynamic Instability and the Mechanism of Flutter

Description: The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom have been determined. The problem resolves itself into the solution of certain definite integrals, which have been identified as Bessel functions of the first and second kind and of zero and first order. The theory, being based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing-section theory relating to the steady case. The air forces being known, the mechanism of aerodynamic instability has been analyzed in detail. An exact solution, involving potential flow and the adoption of the Kutta condition, has been analyzed in detail. An exact solution, involving potential flow and the adoption of the Kutta condition, has been arrived at. The solution is of a simple form and is expressed by means of an auxiliary parameter K.
Date: January 1, 1949
Creator: Theodorsen, Theodore
Partner: UNT Libraries Government Documents Department

Heat transfer to bodies traveling at high speed in the upper atmosphere

Description: A general method has been developed, using the methods of kinetic theory, whereby the surface temperatures of bodies can be calculated for steady flight at any speed in a rarefied gas. The particular solution was made for a flat plate; however, the calculations can be easily extended to bodies of arbitrary shape.
Date: 1949
Creator: Stalder, Jackson R. & Jukoff, David
Partner: UNT Libraries Government Documents Department

Investigation of a systematic group of NACA 1-series cowlings with and without spinners

Description: Report presents the results of an investigation conducted in the Langley propeller research tunnel to study cowling-spinner combinations based on the NACA 1-series nose inlets and to obtain systematic design data for one family of approximately ellipsoidal spinners. In the main part of the investigation, 11 of the related spinners were tested in various combinations with 9 NACA open-nose cowlings, which were also tested without spinners. The effects of location and shape of the spinner, shape of the inner surface of the cowling lip, and operation of a propeller having approximately oval shanks were investigated briefly. In addition, a study was conducted to determine the correct procedure for extrapolating design conditions determined from the low-speed test data to the design conditions at the actual flight Mach number.
Date: 1949
Creator: Nichols, Mark R. & Keith, Arvid L., Jr.
Partner: UNT Libraries Government Documents Department

Plastic Buckling of a Rectangular Plate Under Edge Thrusts

Description: "The fundamental equations for the plastic buckling of a rectangular plate under edge thrusts are developed on the basis of a new set of stress-strain relations for the behavior of a metal in the plastic range. These relations are derived for buckling from a state of uniform compression. The fundamental equation for the buckling of a simply compressed plate together with typical boundary conditions is then developed and the results are applied to calculating the buckling loads of a thin strip, a simply supported plate, and a cruciform section" (p. 1).
Date: 1949
Creator: Handelman, G. H. & Prager, W.
Partner: UNT Libraries Government Documents Department

Recommendations for numerical solution of reinforced-panel and fuselage-ring problems

Description: "Procedures are recommended for solving the equations of equilibrium of reinforced panels and isolated fuselage rings as represented by the external loads and the operations table established according to Southwell's method. From the solution of these equations the stress distribution can be easily determined. The method of systematic relaxations, the matrix-calculus method, and several other methods applicable in special cases are discussed" (p. 1).
Date: 1949
Creator: Hoff, N. J. & Libby, Paul A.
Partner: UNT Libraries Government Documents Department

A simplified method for the determination and analysis of the neutral-lateral-oscillatory-stability boundary

Description: A necessary condition for neutral oscillatory stability is that Routh's discriminant r, formed from the coefficients of the stability equation, is equal to zero. Computations obtained from rsub1=0 and d=0 show very good agreement with the results calculated by the expression for r=0. The nature of the modes of motion as a function of the directional-stability derivative and the effective-dihedral derivative is discussed in detail.
Date: 1949
Creator: Sternfield, Leonard & Gates, Ordway B., Jr.
Partner: UNT Libraries Government Documents Department

Summary of section data on trailing-edge high-lift devices

Description: "A summary has been made of available data on the characteristics of airfoil sections with trailing-edge high-lift devices. Data for plain, split, and slotted flaps are collected and analyzed. The effects of each of the variables involved in the design of the various types of flap are examined and, in cases where sufficient data are given, optimum configurations are deduced. Wherever possible, the effects of airfoil section, Reynolds number, and leading-edge roughness are shown. For single and double slotted flaps, where a large amount of unrelated data are available, maximum lift coefficients of many configurations are presented in tables" (p. 1).
Date: 1949
Creator: Cahill, Jones F.
Partner: UNT Libraries Government Documents Department

Theoretical characteristics in supersonic flow of two types of control surfaces on triangular wings

Description: From Summary :"Methods based on the linearized theory for supersonic flow were used to find the characteristics of two types of control surfaces on thin triangular wings. The first type, the constant-chord partial-span flap, was considered to extend either outboard from the center of the wing or inboard from the wing tip. The second type, the full-triangular-tip flap, was treated only for the case in which the Mach number component normal to the leading edge is supersonic. For each type, expressions were found for the lift, rolling-moment, pitching-moment, and hinge-moment characteristics."
Date: 1949
Creator: Tucker, Warren A. & Nelson, Robert L.
Partner: UNT Libraries Government Documents Department

Laminar mixing of a compressible fluid

Description: From Summary: "A theoretical investigation of the velocity profiles for laminar mixing of a high-velocity stream with a region of fluid at rest has been made assuming that the Prandtl number is unity. A method which involves only quadratures is presented for calculating the velocity profile in the mixing layer for an arbitrary value of the free-stream Mach number. Detailed velocity profiles have been calculated for free-stream Mach numbers of 0, 1, 2, 3, and 5."
Date: January 5, 1949
Creator: Chapman, Dean R.
Partner: UNT Libraries Government Documents Department

Fundamental effects of aging on creep properties of solution-treated low-carbon N-155 alloy

Description: A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.
Date: January 18, 1949
Creator: Frey, D. N.; Freeman, J. W. & White, A. E.
Partner: UNT Libraries Government Documents Department

Investigation at low speeds of the effect of aspect ratio and sweep on rolling stability derivatives of untapered wings

Description: A low-scale wind-tunnel investigation was conducted in rolling flow to determine the effects of aspect ratio and sweep (when varied independently) on the rolling stability derivatives for a series of untapered wings. The rolling-flow equipment of the Langley stability tunnel was used for the tests. The data of the investigation have been used to develop a method of accounting for the effects of the drag on the yawing moment due to rolling throughout the lift range.
Date: January 19, 1949
Creator: Goodman, Alex & Fisher, Lewis R.
Partner: UNT Libraries Government Documents Department

Investigation with an interferometer of the turbulent mixing of a free supersonic jet

Description: The free turbulent mixing of a supersonic jet of Mach number 1.6 has been experimentally investigated. An interferometer, of which a description is given, was used for the investigation. Density and velocity distributions through the mixing zone have been obtained. It was found that there was similarity in distribution at the cross sections investigated and that, in the subsonic portion of the mixing zone, the velocity distribution fitted the theoretical distribution for incompressible flow. It was found that the rates of spread of the mixing zone both into the jet and into the ambient air were less than those of subsonic jets.
Date: January 21, 1949
Creator: Gooderum, Paul B.; Wood, George P. & Brevoort, Maurice J.
Partner: UNT Libraries Government Documents Department

Theoretical lift and damping in roll at supersonic speeds of thin sweptback tapered wings with streamwise tips, subsonic leading edges, and supersonic trailing edges

Description: "On the basis of linearized supersonic-flow theory, generalized equations were derived and calculations made for the lift and damping in roll of a limited series of thin sweptback tapered wings. Results are applicable to wings with streamwise tips and for a range of supersonic speeds for which the wing is wholly contained between the Mach cones springing from the wing apex and from the trailing edge of the root section. A further limitation is that the tip Mach lines may not intersect on the wing" (p. 395).
Date: February 15, 1949
Creator: Malvestuto, Frank S., Jr.; Margolis, Kenneth & Ribner, Herbert S.
Partner: UNT Libraries Government Documents Department

Equilibrium Operating Performance of Axial-Flow Turbojet Engines by Means of Idealized Analysis

Description: "A method of predicting equilibrium operating performance of turbojet engines has been developed, with the assumption of simple model processes for the components. Results of the analysis are plotted in terms of dimensionless parameters comprising critical engine dimensions and over-all operating variables. This investigation was made of an engine in which the ratio of axial inlet-air velocity to compressor-tip velocity is constant, which approximates turbojet engines with axial-flow compressors" (p. 673).
Date: February 25, 1949
Creator: Sanders, John C. & Chapin, Edward C.
Partner: UNT Libraries Government Documents Department

The effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings

Description: From Summary: "An analysis is presented of the effect of torsional flexibility on the rolling characteristics at supersonic speeds of tapered unswept wings with partial-span constant-percent-chord ailerons extending inboard from the wing tip. The geometric variables considered are aspect ratio, taper ratio, aileron span, and aileron chord. The shape of the wing-torsional-stiffness curve is assumed and the twisting moment is considered to result solely from the pressure distribution caused by aileron deflection, so that the necessity of using a successive-approximation method is avoided."
Date: March 8, 1949
Creator: Tucker, Warren A. & Nelson, Robert L.
Partner: UNT Libraries Government Documents Department

On Stability of Free Laminar Boundary Layer Between Parallel Streams

Description: "An analysis and calculations on the stability of the free laminar boundary layer between parallel streams were made for an incompressible fluid using the Tollmien-Schlichting theory of small disturbances. Because the boundary conditions are at infinity, two solutions of the Orr-Sommerfeld stability equations need not be considered, and the remaining two solutions are exponential in character at the infinite boundaries. The calculations show that the flow is unstable except for very low Reynolds numbers" (p. 571).
Date: March 21, 1949
Creator: Lessen, Martin
Partner: UNT Libraries Government Documents Department

Investigations at supersonic speeds of 22 triangular wings representing two airfoil sections for each of 11 apex angles

Description: The results of tests of 22 triangular wings, representing two leading-edge shapes for each of 11 apex angles, at Mach numbers 1.62, 1.92, and 1.40 are presented and compared with theory. All wings have a common thickness ratio of 8 percent and a common maximum-thickness point at 18 percent chord. Lift, drag, and pitching moment are given for all wings at each Mach number. The relation of transition in the boundary layer, shocks on the wing surfaces, and characteristics of the pressure distributions is discussed for several wings.
Date: March 30, 1949
Creator: Love, Eugene S.
Partner: UNT Libraries Government Documents Department

Frequency response of linear systems from transient data

Description: "Methods are presented that use general correlative time-response input and output data for a linear system to determine the frequency-response function of that system. These methods give an exact description of any linear system for which such transient data are available. Examples are shown of application of a method to both an underdamped and a critically damped exact second-order system, and to an exact first-order system with and without dead time. Experimental data for a turbine-propeller engine showing the response of engine speed to change in propeller-blade angle are presented and analyzed" (p. 547).
Date: April 1, 1949
Creator: Laverne, Melvin E. & Boksenbom, Aaron S.
Partner: UNT Libraries Government Documents Department