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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Serial/Series Title: NACA Technical Reports
 Collection: National Advisory Committee for Aeronautics Collection
Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades

Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades

Date: January 1, 1948
Creator: Sinnette, John T & Voss, William J
Description: A theory has been developed for resetting the blade angles of an axial-flow compressor in order to improve the performance at speeds and flows other than the design and thus extend the useful operating range of the compressor. The theory is readily applicable to the resetting of both rotor and stator blades or to the resetting of only the stator blades and is based on adjustment of the blade angles to obtain lift coefficients at which the blades will operate efficiently. Calculations were made for resetting the stator blades of the NACA eight-stage axial-flow compressor for 75 percent of design speed and a series of load coefficients ranging from 0.28 to 0.70 with rotor blades left at the design setting. The NACA compressor was investigated with three different blade settings: (1) the design blade setting, (2) the stator blades reset for 75 percent of design speed and a load coefficient of 0.48, and (3) the stator blades reset for 75 percent of design speed and a load coefficient of 0.65.
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Determination of Stresses in Gas-turbine Disks Subjected to Plastic Flow and Creep

Determination of Stresses in Gas-turbine Disks Subjected to Plastic Flow and Creep

Date: January 1, 1948
Creator: Manson, S. S.
Description: None
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General Theory of Aerodynamic Instability and the Mechanism of Flutter

General Theory of Aerodynamic Instability and the Mechanism of Flutter

Date: January 1, 1949
Creator: Theodorsen, Theodore
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.
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Thin oblique airfoils at supersonic speed

Thin oblique airfoils at supersonic speed

Date: January 1, 1946
Creator: Jone, Robert T
Description: The well-known methods of thin-airfoil theory have been extended to oblique or sweptback airfoils of finite aspect ratio moving at supersonic speeds. The cases considered thus far are symmetrical airfoils at zero lift having plan forms bounded by straight lines. Because of the conical form of the elementary flow fields, the results are comparable in simplicity to the results of the two-dimensional thin-airfoil theory for subsonic speeds. In the case of untapered airfoils swept back behind the Mach cone the pressure distribution at the center section is similar to that given by the Ackeret theory for a straight airfoil. With increasing distance from the center section the distribution approaches the form given by the subsonic-flow theory. The pressure drag is concentrated chiefly at the center section and for long wings a slight negative drag may appear on outboard sections. (author).
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Tank tests to determine the effect on planing-tail hulls of varying length, width, and plan-form taper of afterbody

Tank tests to determine the effect on planing-tail hulls of varying length, width, and plan-form taper of afterbody

Date: January 1, 1946
Creator: Dawson, John R
Description: Tests were conducted in Langley Tank no. 2 on models of an unconventional flying-boat hull called a planing-tail hull to determine the effects on resistance of varying a number of afterbody parameters. The effects of varying length, width, and plan-form taper of the afterbody are presented. Tests were made with afterbodies of two widths, two lengths, and two tapers. In the tests the depth of step and the angle of afterbody keel were held constant.(author).
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The stability of the laminar boundary layer in a compressible fluid

The stability of the laminar boundary layer in a compressible fluid

Date: January 1, 1947
Creator: Lees, Lester
Description: Report is a continuation of a theoretical investigation of the stability of the laminar boundary layer in a compressible fluid. An approximate estimate for the minimum critical Reynolds number, or stability limit, is obtained in terms of the distribution of the kinematic viscosity and the product of the mean density and mean vorticity across the boundary layer. The extension of the results of the stability analysis to laminar boundary-layer gas flows with a pressure gradient in the direction of the free stream is discussed. (author).
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Summary of Airfoil Data

Summary of Airfoil Data

Date: January 1, 1945
Creator: Abbott, Ira H
Description: The historical development of NACA airfoils is briefly reviewed. New data are presented that permit the rapid calculation of the approximate pressure distributions for the older NACA four-digit and five-digit airfoils by the same methods used for the NACA 6-series airfoils. The general methods used to derive the basic thickness forms for NACA 6 and 7-series airfoils together with their corresponding pressure distributions are presented. Detail data necessary for the application of the airfoils to wing design are presented in supplementary figures placed at the end of the paper. The report includes an analysis of the lift, drag, pitching-moment, and critical-speed characteristics of the airfoils, together with a discussion of the effects of surface conditions. Available data on high-lift devices are presented. Problems associated with lateral-control devices, leading-edge air intakes, and interference are briefly discussed, together with aerodynamic problems of application. (author).
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Experiments on stability of Bunsen-burner flames for turbulent flow

Experiments on stability of Bunsen-burner flames for turbulent flow

Date: January 1, 1948
Creator: Bollinger, Lowell M
Description: The results of a study of the stability of propane-air flames on bunsen-burner tubes are presented. Fuel-air ratio, tube diameter, and Reynolds number were the primary variables. Regions of stability are outlined in plots of fuel-air ratio as a function of Reynolds number for flames seated on the burner lip and for flames suspended well above the burner. For fully developed flow, turbulent as well as laminar, the velocity gradient at the burner wall is a satisfactory variable for correlating the fuel-air ratio required for blow-off of seated flames for fuel-air ratios of less than 15 percent. For turbulent flames, wall velocity serves as a correlating variable in the same fuel-air-ratio range. (author).
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A unified theory of plastic buckling of columns and plates

A unified theory of plastic buckling of columns and plates

Date: January 1, 1948
Creator: Stowell, Elbridge Z
Description: On the basis of modern plasticity considerations, a unified theory of plastic buckling applicable to both columns and plates has been developed. For uniform compression, the theory shows that long columns which bend without appreciable twisting require the tangent modulus and that long flanges which twist without appreciable bending require the secant modulus. Structures that both bend and twist when they buckle require a modulus which is a combination of the secant modulus and the tangent modulus.
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Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream

Theoretical study of air forces on an oscillating or steady thin wing in a supersonic main stream

Date: July 1, 1947
Creator: Garrick, I E
Description: A theoretical study, based on the linearized equations of motion for small disturbance, is made of the air forces on wings of general plan forms moving forward at a constant supersonic speed. The boundary problem is set up for both the harmonically oscillating and the steady conditions. Two types of boundary conditions are distinguished, which are designated "purely supersonic" and "mixed supersonic." the method is illustrated by applications to a number of examples for both the steady and the oscillating conditions. The purely supersonic case involves independence of action of the upper and lower surfaces of the airfoil and present analysis is mainly concerned with this case. A discussion is first given of the fundamental or elementary solution corresponding to a moving source. The solutions for the velocity potential are then synthesized by means of integration of the fundamental solution for the moving source. The method is illustrated by applications to a number of examples for both the steady and the oscillating cases and for various plan forms, including swept wings and rectangular and triangular plan forms. The special results of a number of authors are shown to be included in the analysis.
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