UNT Libraries Government Documents Department - 188 Matching Results

Search Results

prev Results: 49 - 72 next
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
Item Type: Refine your search to only Report
open access

Laws of Flow in Rough Pipes

Description: An experimental investigation is made of the turbulent flow of water in pipes with various degrees of relative roughness. The pipes range in size from 25 to 100 millimeters in diameter and from 1800 to 7050 millimeters in length. Flow velocities permitted Reynolds numbers from about 10 (sup. 4) to 10 (sup. 6). The laws of resistance and velocity distributions were obtained as a function of relative roughness and Reynolds number. Mixing length, as described by Prandtl's mixing-length formula, is… more
Date: November 1950
Creator: Nikuradse, J.
Item Type: Refine your search to only Report
open access

On Stability and Turbulence of Fluid Flows

Description: This investigation is divided into two parts, the treatment of the stability problem of fluid flows on the one hand, and that of the turbulent motion on the other. The first part summarizes all previous investigations under a unified point of view, that is, sets up as generally as possible the conditions under which a profile possesses unstable or stable characteristics, and indicates the methods for solution of the stability equation for any arbitrary velocity profile and for calculation of th… more
Date: June 1951
Creator: Heisenberg, Werner
Item Type: Refine your search to only Report
open access

The Structure of Airy's Stress Function in Multiply Connected Regions

Description: In solving two-dimensional problems using Airy's stress function for multiply connected regions, the form of the function depends on the dislocations and boundary forces present. The structure of Airy's function is shown to consist of a part expressible in terms of boundary forces and a part expressible in the manner of Poincare. Meanings of the constants occurring in Poincare's expression are discussed.
Date: July 1951
Creator: Grioli, Giusippe
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Report
open access

Dependence of the Elastic Strain Coefficient of Copper on the Pre-Treatment

Description: The effect of various pre-treatments on the elastic strain coefficient (alpha) (defined as the reciprocal of the modulus of elasticity E) (Epsilon) and on the mechanical hysteresis of copper has been investigated. Variables comprising the pre-treatments were pre-straining by stretching in a tensile testing machine and by drawing through a die, aging at room and elevated temperatures and annealing. The variation of the elastic strain coefficient with test stress was also investigated.
Date: August 1950
Creator: Kuntze, Wilhelm
Item Type: Refine your search to only Report
open access

Method of Successive Approximations for the Solution of Certain Problems in Aerodynamics

Description: A method of successive approximations for the solution of problems in the fields of diffusion, boundary-layer flow, and heat-transfer is illustrated by solving problems in each of these fields. In most of the examples, the approximate solutions are compared with known accurate solutions and the agreement is shown to be good.
Date: April 1951
Creator: Shvets, M. E.
Item Type: Refine your search to only Report
open access

Investigations of the Wall-Shearing Stress in Turbulent Boundary Layers

Description: Because of the unsatisfactory state of knowledge concerning the surface shearing stress of boundary layers with pressure gradients, the problem is re-examined. It is found that for general turbulent boundary layers in wall proximity, that is, in the laminar sublayer, in the transition zone and in the part of the completely turbulent zone near the wall, the same universal law applies as for the plate flow.
Date: May 1950
Creator: Ludwieg, Hubert & Tillmann, W.
Item Type: Refine your search to only Report
open access

Two-Dimensional Symmetrical Inlets With External Compression

Description: The purpose of inlets like, for instance, those of air-cooled radiators and scoops is to take a certain air quantity out of the free stream and to partly convert the free-stream velocity into pressure. In the extreme case this pressure conversion may occur either entirely in the interior of the inlet (inlet with internal compression) or entirely in the free stream ahead of the inlet (inlet with external compression). In this report a theory for two-dimensional inlets with external compression i… more
Date: March 1950
Creator: Ruden, P.
Item Type: Refine your search to only Report
open access

Calculation of the Lateral-Dynamic Stability of Aircraft

Description: "Graphs and formulas are given with the aid of which all the aerodynamic coefficients required for computing the lateral dynamic stability can be determined. A number of numerical examples are given for obtaining the stability derivatives and solving the characteristic-stability equation. Approximate formulas are derived with the aid of which rapid preliminary computations may be made and the stability coefficients corrected for certain modifications of the airplane" (p. 1).
Date: February 1952
Creator: Raikh, A.
Item Type: Refine your search to only Report
open access

Contribution to the Problem of Buckling of Orthotropic Plates, With Special Reference to Plywood

Description: Planar stress-strain relations and bending stress-strain relations are presented for elastic orthotropic plates and specialized to plywood. These relations are used to derive the differential equation and energy expression for the buckling of orthotropic rectangular plates whose principal stiffness directions are not parallel to the plate edges. Buckling analyses are made for the case of pure compression and pure shear of a long plate-strip.
Date: August 1950
Creator: Thielemann, Wilhelm
Item Type: Refine your search to only Report
open access

Turbulence and Heat Stratification

Description: With applications to meteorology in view, the method of small oscillations is used to investigate the stability of a plane laminar boundary layer in which the density depends in a special way on the distance from the plate. It is found that for a constant Froude number the flow becomes more stable as the Richardson number increases until, at a critical value of the Richardson number that depends on the Froude number, the flow is stable for all disturbance wave lengths and Reynolds numbers. The … more
Date: October 1950
Creator: Schlichting, Hermann
Item Type: Refine your search to only Report
open access

On the Theory of the Propagation of Detonation in Gaseous Systems

Description: "The existing theory of detonation is critically examined. It is shown that the considerations with which the steady value of the velocity of detonation is chosen are not convincing. In connection with the problem of the process of the chemical reaction in a detonation wave, the objections raised against the conceptions of Le Chatelier and Vieille of the 19th century with regard to the ignition of the gas by the shock wave are refuted" (p. 1).
Date: November 1950
Creator: Zeldovich, Y. B.
Item Type: Refine your search to only Report
open access

Sideslip in a Viscous Compressible Gas

Description: By an analysis of the Navier-Stokes equations it is shown that the aerodynamic coefficients of an infinite rectangular swept wing in an isothermal or adiabatic flow of a compressible gas can be determined from the aerodynamic coefficients of the unswept wing. When the flow is neither isothermal nor adiabatic, a three-dimensional boundary layer theory is developed and applied to the special case of a swept flat plate.
Date: April 1951
Creator: Struminsky, V. V.
Item Type: Refine your search to only Report
open access

The Solution of the Laminar-Boundary-Layer Equation for the Flat Plate for Velocity and Temperature Fields for Variable Physical Properties and for the Diffusion Field at High Concentration

Description: "In connection with Pohlhausen's solution for the temperature field on the flat plate, a series of formulas were indicated by means of which the velocity and temperature field for variable physical characteristics can be computed by an integral equation and an iteration method based on it. With it, the following cases were solved: On the assumption that the viscosity simply varies with the temperature while the other fluid properties remain constant, the velocity and temperature field on the he… more
Date: May 1950
Creator: Schuh, H.
Item Type: Refine your search to only Report
open access

Behavior of Fast Moving Flow of Compressible Gas in Cylindrical Pipe in Presence of Cooling

Description: For compressible flow with friction in a cylindrical pipe the momentum, continuity, and heat-transfer equations are examined to determine whether an increase in Mach number ("thermal" Laval nozzle) is obtainable through heat conduction from the gas through the pipe walls. The analysis is based on the assumption that the wall temperature is negligibly small in comparison with the stagnation temperature of the gas. The analysis leads to a negative result. When the gas cooling is increased by also… more
Date: September 1951
Creator: Varshavsky, G. A.
Item Type: Refine your search to only Report
open access

Critical Velocities of Ultracentrifuges

Description: The Euler equations for the rotation of a solid body are applied to the problem of the motion of ultracentrifuges. Particular attention is paid to the problem of the passage of an ultracentrifuge rotor through the critical velocity. The factors that affect the passage of rotors through the critical point are stressed.
Date: March 1951
Creator: Sokolov, V. I.
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Report
open access

The Gas Kinetics of Very High Flight Speeds

Description: The aerodynamic forces on bodies of arbitrary shape were investigated under conditions such that the mean free path of the air molecule is greater than the dimensions of the body. Air pressures and friction forces were calculated from gas kinetic theory for surfaces facing both toward and away from the air stream at any angle. Air forces for an atmosphere of definite composition (molecular hydrogen) were calculated as a function of the flight velocity.
Date: May 1950
Creator: Sänger, Eugen
Item Type: Refine your search to only Report
open access

Instrument for Measuring the Wall Shearing Stress of Turbulent Boundary Layers

Description: "It is shown that at a smooth wall in a turbulent boundary layer the velocity profile next to the wall is dependent, aside from the material constants of the flowing medium, only on the shearing stress transmitted to the wall, even with pressure rise or with pressure drop. Consequently, the heat transfer of a small element that is built into the wall and has a higher temperature than that of the flowing medium is a measure of the wall shearing stress. Theoretical considerations indicate that th… more
Date: May 1950
Creator: Ludwieg, H.
Item Type: Refine your search to only Report
Back to Top of Screen