UNT Libraries Government Documents Department - 187 Matching Results

Search Results

prev Results: 31 - 54 next
open access

Deplacement Effect of the Laminar Boundary Layer and the Pressure Drag

Description: The displacement effect of the boundary layer on the outer frictionless flow is discussed for both steady and unsteady flows. The analysis is restricted to cases in which the potential flow pressure distribution remains valid for the boundary-layer calculation. Formulas are given for the dependence of the pressure drag, friction drag, and total drag of circular cylinders on the time from the start of motion for cases in which the velocity varies as a power of the time. Formulas for the location… more
Date: October 1951
Creator: Görtler, H.
open access

Determination of the Elastic Constants of Airplane Tires

Description: For determination of the elastic constants of airplane tires which are required for the numerical calculations of the shimmy properties of nose and tail wheels, deformation measurements were carried out on four different tires. For this purpose, the tires were loaded in each case with a normal load and then with a lateral force, a tangential force, and a moment. Moreover, the weight and the mass moment of inertia about a vertical axis were determined for the various tires.
Date: November 1954
Creator: Boeckh
open access

The Development of a Hollow Blade for Exhaust Gas Turbines

Description: The subject of the development of German hollow turbine blades for use with internal cooling is discussed in detail. The development of a suitable blade profile from cascade theory is described. Also a discussion of the temperature distribution and stresses in a turbine blade is presented. Various methods of manufacturing hollow blades and the methods by which they are mounted in the turbine rotor are presented in detail.
Date: December 1950
Creator: Kohlmann, H.
open access

Development of a Laminar Boundary Layer Behind a Suction Point

Description: A theoretical investigation is made of the development of a laminar boundary layer behind a suction slot that is assumed to cut off part of the boundary layer without exerting any sink effect. The development, which is approximate, is based on the heat conduction equation. The heat conduction equation enters the analysis through a linearization of the Prandtl-Mises form of the boundary-layer equation.
Date: March 1952
Creator: Wuest, Walter
open access

Directional Stability of Towed Airplanes

Description: "So far, very careful investigations have been made regarding the flight properties, in particular the static and dynamic stability, of engine-propelled aircraft and of untowed gliders. In contrast, almost no investigations exist regarding the stability of airplanes towed by a towline. Thus, the following report will aim at investigating the directional stability of the towed airplane and, particularly, at determining what parameters of the flight attitude and what configuration properties affe… more
Date: January 1956
Creator: Söhne, W.
open access

Drop Hammer Tests With Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures

Description: "Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly" (p. 1).
Date: July 1954
Creator: Kranz
open access

Effect of Fatigue Crack on Static Strength: 2014-T6, 2024-T4, 6061-T6, 7075-T6 Open-Hole Monobloc Specimens

Description: "Static tensile test results are presented for specimens of 2014-T6, 2024-T4, 6061-T6, and 7075-T6 aluminum alloy containing fatigue cracks. The results are found to be in good agreement with the results reported for similar tests from other sources. The results indicate that the presence of a fatigue crack reduced the static strength, in all cases, by an amount larger than the corresponding reduction in net area; the 6061-T6 alloy specimens were least susceptible to the crack and the 7075-T6 a… more
Date: May 1957
Creator: Nordmark, Glenn E. & Eaton, Ian D.
open access

The Effect of Free-Stream Turbulence on Heat Transfer From a Flat Plate

Description: Turbulence was generated by using screens, and the turbulence percentage was measured by a hot-wire anemometer both in the boundary layer and the free stream. The local heat-transfer coefficient was measured at 12 locations along the plate for the cases of various turbulence levels. The transition Reynolds number from laminar to turbulent flow decreases as the main-stream turbulence level increases. In the range of laminar heat transfer the effect of turbulence in the main flow was not great, b… more
Date: September 1958
Creator: Sugawara, Sugao; Sato, Takashi; Komatsu, Hiroyasu & Osaka, Hiroichi
open access

The Effect of High Viscosity on the Flow Around a Cylinder and Around a Sphere

Description: "For the determination of the flow velocity one is accustomed to measure the impact pressure, i.e., the pressure intensity in front of an obstacle. In incompressible fluids the impact pressure is yv(sup 2)/2g if the influence of viscosity can be neglected. Such an influence is appreciable, however, when the Reynolds number corresponding to impact tube radius is under about 100, and must consequently be considered, if the velocity determination is not to be faulty" (p. 1).
Date: June 1952
Creator: Homann, F.
open access

Effect of Intense Sound Waves on a Stationary Gas Flame

Description: Intense sound waves with a resonant frequency of 5000 cycles per second were imposed on a stationary propane-air flame issuing from a nozzle. In addition to a slight increase of the flame velocity, a fundamental change both in the shape of the burning zone and in the flow pattern could be observed. An attempt is made to explain the origin of the variations in the flame configuration on the basis of transition at the nozzle from jet flow to potential flow.
Date: July 1950
Creator: Hahnemann, H. & Ehret, L.
open access

The Effect of Solid Admixtures on the Velocity of Motion of a Free Dusty Air Jet

Description: "In dusty air flows occurring in industrial practice in transport by air pressure of friable materials, in the drying, annealing, and so forth, of a pulverized solid mass in suspension, and in other processes, the concentration of solid particles usually has a magnitude of the order of 1 kg per 1 kg of air. At such a concentration, the ratio of the volume of the particles to the volume of the air is small (less than one-thousandth part). However, regardless of this, the presence of a solid admi… more
Date: April 1957
Creator: Chernov, A. P.
open access

Effects of Intermittent Versus Continuous Heating upon the Tensile Properties of 2024-T4, 6061-T6 and 7075-T6 Alloys

Description: In some applications, aluminum alloys are subjected to intermittent heating at elevated temperature. It is generally considered that the effects of such intermittent heating are cumulative, and therefore are the same as if the heating had been continuous for the same total length of time. The object of these tests was to determine the effects of intermittent and continuous heating at 300 and 400 F, for total periods of 100 and 200 hr, upon the tensile properties of 2024-T4 and 6061-T6 alloy rol… more
Date: August 1956
Creator: Stickley, G. W. & Anerson, H. L.
open access

Elliptic Functions and Integrals with Real Modulus in Fluid Mechanics

Description: "Advantage of the elliptic functions and of the more general functions of Schwarz for fluid mechanics. Flows outside and inside polygons. Application to the calculation of an elbow diffuser for a wind tunnel. Properties of the elliptic integrals of the first kind and of the elliptic functions" (p. 1).
Date: June 1958
Creator: Legendre, Robert
open access

Equations of Motion of a Rocket

Description: "In considering the motion of the rocket, at each instant of time only the state of those material particles which at that instant are within the control surface passing through the exterior surface of the body of the rocket and the exit section of the nozzle shall be included. In order to obtain the equations of motion of the rocket, the following procedure is used. An arbitrary but fixed instant of time is considered" (p. 1).
Date: April 1950
Creator: Gantmacher, F. R. & Levin, L. M.
open access

Evaporation, Heat Transfer, and Velocity Distribution in Two-Dimensional and Rotationally Symmetrical Laminar Boundary-Layer Flow

Description: The fundamental boundary layer equations for the flow, temperature and concentration fields are presented. Two dimensional symmetrical and unsymmetrical and rotationally symmetrical steady boundary layer flows are treated as well as the transfer boundary layer. Approximation methods for the calculation of the transfer layer are discussed and a brief survey of an investigation into the validity of the law that the Nusselt number is proportional to the cube root of the Prandtl number is presente… more
Date: February 1958
Creator: Frössling, Nils
open access

Exact Solutions of Equations of Gas Dynamics

Description: This document presents equations for the two-dimensional stationary problem of gas dynamics, and uses them to derive other equations, including equations for vorticity.
Date: June 1950
Creator: Kiebel, I. A.
open access

The Excitation of Unstable Perturbations in a Laminar Friction Layer

Description: "With the aid of the method of small oscillations which was used successfully in the investigation of the stability of laminar velocity distributions in the presence of two-dimensional perturbations, the excitation of the unstable perturbations for the Hartree velocity distributions occurring in plane boundary-layer flow for decreasing and increasing pressure is calculated as a supplement to a former report. The results of this investigation are to make a contribution toward calculation of the … more
Date: September 1952
Creator: Pretsch, Joachim
open access

Exhaust Turbine and Jet Propulsion Systems

Description: DVL experimental and analytical work on the cooling of turbine blades by using ram air as the working fluid over a sector or sectors of the turbine annulus area is summarized. The subsonic performance of ram-jet, turbo-jet, and turbine-propeller engines with both constant pressure and pulsating-flow combustion is investigated. Comparison is made with the performance of a reciprocating engine and the advantages of the gas turbine and jet-propulsion engines are analyzed. Nacelle installation meth… more
Date: April 1951
Creator: Leist, Karl & Knörnschild, Eugen
open access

Experiments on a Tail-Wheel Shimmy

Description: "Model tests on the "running belt" and tests with a full-scale tail wheel were made on a rotating drum as well as on a runway in order to investigate the causes of the undesirable shimmy phenomena frequently occurring on airplane tail wheels, and the means of avoiding them. The small model (scale 1:10) permitted simulation of the mass, moments of inertia, and fuselage stiffness of the airplane and determination of their influence on the shimmy, whereas by means of the larger model with pneumati… more
Date: October 1954
Creator: Dietz, O. & Harling, R.
open access

Extension to the Cases of Two Dimensional and Spherically Symmetric Flows of Two Particular Solutions to the Equations of Motion Governing Unsteady Flow in a Gas

Description: "The author previously discovered two interesting particular solutions to the equations of motion describing unsteady flow in a gas confined solely to a one-dimensional duct. These solutions are now extended to cover the more noteworthy cases of central symmetry in two and three dimensions" (p. 1).
Date: June 1952
Creator: Pozzi, Lorenzo
open access

Extreme Speeds and Thermodynamic States in Supersonic Flight

Description: "The increasing importance of high-speed flow leads to similar problems in various fields of research which are summarized in what follows. Typical of all cases is the conversion of high kinetic energy into extreme thermodynamic states with temperatures of several thousand degrees, frequently connected with dissociation and ionization of the gas involved. There is also a characteristic small sensitivity to the processes discussed in the case of gases of low molecular weight (light gases)" (p. 1… more
Date: April 1958
Creator: Oswatitsch, Klaus
Back to Top of Screen