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The effect of compressibility on two-dimensional tunnel-wall interference for a symmetrical airfoil

Description: Summary: The effective change in the velocity of flow past a wing section, caused by the presence of wind-tunnel walls, is known for potential flow. This theory is extended by investigation of the two-dimensional compressible flow past a thin Rankine Oval. It is shown that for a symmetrical section at zero angle of attack the velocity increment due to the tunnel walls in the incompressible case must be multiplied by the factor 1/1-M^2 to take account of compressibility effects. The Mach number, M, corresponds to conditions in the wind-tunnel test section with the model removed (p. 1.).
Date: May 1943
Creator: Nitzberg, Gerald E.
Partner: UNT Libraries Government Documents Department

Importance of Supernovae at z<0.1 for Probing Dark Energy

Description: Supernova experiments to characterize dark energy require a well designed low redshift program; we consider this for both ongoing/near term (e.g. Supernova Legacy Survey) and comprehensive future (e.g., SNAP) experiments. The derived criteria are: a supernova sample centered near z=0.05 comprising 150-500 (in the former case) and 300-900 (in the latter case) well measured supernovae. Low redshift Type Ia supernovae play two important roles for cosmological use of the supernova distance-redshift relation: as an anchor for the Hubble diagram and as an indicator of possible systematics. An innate degeneracy in cosmological distances implies that 300 nearby supernovae nearly saturate their cosmological leverage for the first use, and their optimum central redshift is z=0.05. This conclusion is strengthened upon including velocity flow and magnitude offset systematics. Limiting cosmological parameter bias due to supernova population drift (evolution) systematics plausibly increases the requirement for the second use to less than about 900 supernovae.
Date: February 20, 2007
Creator: Miller, Jeanne M & Linder, E.V.
Partner: UNT Libraries Government Documents Department

A linearized solution for time-dependent velocity potentials near three-dimensional wings at supersonic speeds

Description: Report presenting a source-distribution method for deriving a solution for the time-dependent surface velocity potential of thin finite wings at supersonic speeds. It is illustrated by evaluating the upwash over the tip of an arbitrary-plan-boundary wing with a supersonic and subsonic leading edge.
Date: September 1948
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

Tests of a New Model of Paclitaxel-Induced Neuropathy and the Effects of Paclitaxel on the Dorsal Root Ganglia

Description: This study examined a new model of paclitaxel-induced neuropathic pain and the effects of systemic paclitaxel on the gap junction protein subunit Cx43 and potassium inwardly-rectifying channel Kir4.1 within the dorsal root ganglia. In the new neuropathic pain model, subplantar injections of paclitaxel resulted in decreased conduction velocities of A-beta fiber compound action potentials in the sciatic (5.9%) and tibial nerves (6.8%) as well as in M (10.6%) and H (10.2%) waves. By using repeated recordings it was found that following paclitaxel injection, conduction velocities in the contralateral plantar nerve increased (9.2%). Systemic injections of paclitaxel resulted in reduced Kir4.1 immunolabeling in the dorsal root ganglia compared to vehicle injections. This reduction was observed in total labeling (32.4%) as well as in areas of intense labeling (28.7%). Reductions in overall Cx43 immunolabeling (25%) and area (25%) following systemic paclitaxel injections were not statistically significant. The results of these studies suggest that subplantar injections of paclitaxel can result in reduced peripheral nerve conduction velocities. The results also show that a unilateral neuropathy can result in contralateral changes in conduction velocities. The effects of paclitaxel on reducing Kir4.1 levels suggest that neuropathic pain caused by paclitaxel may share mechanisms in common with other types of neuropathies which show similar changes in Kir4.1 levels.
Date: August 2011
Creator: McWilliams, Steven P.
Partner: UNT Libraries

The effect of flight path inclination on airplane velocity

Description: This report was prepared at the request of the National Advisory Committee for Aeronautics in order to supply a systematic study of the relations between the flight velocity V and its horizontal component V subscript H, in power glides. Curves of V and V subscript H plotted against the inclination of the flight path 0 are given, together with curves which show the maximum values of V subscript H and the corresponding values of 0. Curves are also given showing the effect of small departures from the horizontal in high speed performance testing.
Date: January 1927
Creator: Diehl, Walter S.
Partner: UNT Libraries Government Documents Department

Design of two-dimensional channels with prescribed velocity distributions along the channel walls

Description: "A general method of design is developed for two-dimensional unbranched channels with prescribed velocities as a function of arc length along the channel walls. The method is developed for both compressible and incompressible, irrotational, nonviscous flow and applies to the design of elbows, diffusers, nozzles, and so forth. In part I solutions are obtained by relaxation methods; in part II solutions are obtained by a Green's function. Five numerical examples are given in part I including three elbow designs with the same prescribed velocity as a function of arc length along the channel walls but with incompressible, linearized compressible, and compressible flow" (p. 153).
Date: July 25, 1951
Creator: Stanitz, John D.
Partner: UNT Libraries Government Documents Department

Theoretical lift distribution and upwash velocities for thin wings at supersonic speeds

Description: Report presenting a method for calculating the upwash-velocity component in the vicinity of thin wings at supersonic speeds. The method is applied to obtain an expression for the upwash over wing tips of fairly general plan form and profile.
Date: November 1947
Creator: Evvard, John C. & Turner, L. Richard
Partner: UNT Libraries Government Documents Department

General instability criterion of laminar velocity distributions

Description: The present paper describes the results of a stability investigation on symmetrical velocity profiles in a channel and of boundary-layer profiles. The effect of friction was assumed to be vanishing and did not occur in the stability consideration so far as it had been resorted to for preparatory asymptotic considerations. Proceeding on very general premises as regards the form of the velocity distribution, a proof was deduced of the elementary theorem that velocity profiles with inflection points are unstable.
Date: April 1936
Creator: Tollmien, W.
Partner: UNT Libraries Government Documents Department

Experimental investigation of velocity distributions of downstream of single duct bends

Description: Report presenting measurements of the velocity distributions at the outlet of a large number of duct elbows of round and elliptical as well as square and rectangular cross section at a range of Reynolds numbers. Special investigations include measurements of the decay of velocity patterns produced by curved ducts and the effect of asymmetrical upstream velocity distributions. Results regarding typical distributions, tabulation of principal results, and special investigations are provided.
Date: January 13, 1947
Creator: Weske, John R.
Partner: UNT Libraries Government Documents Department

The Limiting Velocity in Falling from a Great Height

Description: The purpose of this report is to give a simple treatment of the problem of calculating the final or limiting velocity of an object falling in vertical motion under gravity in a resisting medium. The equations of motion are easily set up and integrated when the density of the medium is constant and the resistance varies as the square of the velocity. The results show that the fundamental characteristics of the vertical motion under gravity in a resisting medium is the approach to a terminal or limiting velocity, whether the initial downward velocity is less or greater than the limiting velocity. This method can be used to calculate the terminal velocity of a bomb trajectory.
Date: 1919
Creator: Wilson, Edwin Bidwell
Partner: UNT Libraries Government Documents Department

The numerical solution of compressible fluid flow problems

Description: Numerical methods have been developed for obtaining the steady, adiabatic flow field of a frictionless, perfect gas about arbitrary two-dimensional bodies. The solutions include the subsonic velocity regions, the supersonic velocity regions, and the transition compression shocks, if required. Furthermore, the rotational motion and entropy changes following shocks are taken into account. Extensive use is made of the relaxation method. In this report the details of the methods of solution are emphasized so as to permit others to solve similar problems. Solutions already obtained are mentioned only by way of illustrating the possibilities of the methods described. The methods can be applied directly to wind tunnel and free air tests of arbitrary airfoil shapes at subsonic, sonic, and supersonic speeds.
Date: May 1944
Creator: Emmons, Howard W.
Partner: UNT Libraries Government Documents Department

A velocity-correction formula for the calculation of transonic Mach number distributions over diamond-shaped airfoils

Description: Report presenting a velocity-correction formula for the purpose of calculating, from the known Mach number distribution for a diamond-shaped airfoil at a stream Mach number of 1.0, Mach number distributions on the same airfoil at speeds from a Mach number of about 0.8 to shock-attachment Mach number. An expression for the rate of change of local Mach number with stream Mach number is derived and an explicit equation for the drag coefficient as a function of stream Mach number and thickness ratio is given.
Date: November 1951
Creator: Ivey, H. Reese & Harder, Keith C.
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

Optimum Water Velocity for the Converter Reactor

Description: Abstract: "Two cases are considered. In Case I, the reactor water velocity is optimized to obtain a minimum annual cost (including amortization and operating costs) for the cooling system along. The optimum velocity for a 310 megawatt reactor is calculated to be ~25 feet per second, compared to the present design value of 30 feet per second. In Case II, the velocity which will give the minimum cost of product under the assumptions of varying power and production rate is found to be in the range from ~25 to ~40 feet per second, depending on the assumptions with respect to the variation of total investment in the reactor complex with design production capacity."
Date: June 18, 1952
Creator: Cooley, William C.
Partner: UNT Libraries Government Documents Department

A simple method for estimating terminal velocity including effect of compressibility on drag

Description: Report presenting a generalized drag curve providing an estimate for the drag rise due to compressibility as obtained from an analysis of wind-tunnel data of several airfoils, fuselages, nacelles, and windshields at speeds up to and above the wing critical speed. Results regarding drag characteristics and terminal-velocity calculation are provided.
Date: August 1945
Creator: Bielat, Ralph P.
Partner: UNT Libraries Government Documents Department

Induced Velocities Near a Lifting Rotor With Nonuniform Disk Loading

Description: A method is given for converting known uniformly loaded rotor induced velocities to correspond with arbitrary axisymmetric nonuniform disk load distributions. Numerical results for two specific distributions are given in chart form. Symmetry relations and relations between radial disk loading and wake velocities are developed. Experimental flow measurements are presented and compared with theory. Reasonable agreement is shown in the forward part of the flow when nonuniform loading is assumed, but far behind the rotor the flow is more like that of a wing.
Date: April 1956
Creator: Heyson, Harry H. & Katzoff, S.
Partner: UNT Libraries Government Documents Department

Investigation of Slipstream Velocity

Description: "These experiments were made at the request of the Bureau of Aeronautics, Navy Department, to investigate the velocity of the air in the slipstream in horizontal and climbing flight to determine the form of expression giving the slipstream velocity in terms of the airspeed of the airplane. The method used consisted in flying the airplane both on a level course and in climb at full throttle and measuring the slipstream velocity at seven points in the slipstream for the whole speed range of the airplane in both conditions. In general the results show that for both condition, horizontal and climbing flights, the slipstream velocity v subscript 3 and airspeed v can be represented by straight lines and consequently the equations are of the form: v subscript s = mv+b where m and b are constant" (p. 199).
Date: January 1925
Creator: Crowley, J. W., Jr.
Partner: UNT Libraries Government Documents Department

Turbulent Jet Expansion

Description: This report was made to study the velocity distribution in an open, in a partially open, and in a partially expanding jet. The open-jet observations reveal minor systematic discrepancies from Tollmien's theoretical velocity distribution. The shearing-stress distribution for the partially open jet was determined. The value derived for the ratio of mixing distance to jet width was found to be in close agreement with the corresponding value for the open-jet boundary.
Date: March 1936
Creator: Förthmann, E.
Partner: UNT Libraries Government Documents Department

Determining the Velocity Distribution in the Boundary Layer of an Airfoil Fitted With a Rotary Cylinder

Description: In the closer investigation of the results obtained from a wing model with a rotary cylinder mounted in its leading edge (NACA TM's 307 and 354), the velocity distribution in the vicinity of the surface of the model was determined by a hot-wire anemometer. The results confirmed the belief that the rotary cylinder had considerable effect on the air flow, but demonstrated the fact that the direct influence of the cylinder is confined to a very thin layer in immediate proximity to the surface.
Date: May 1927
Creator: Van der Hegge Zijnen, B. G.
Partner: UNT Libraries Government Documents Department

Observations on the Method of Determining the Velocity of Airships

Description: To obtain the absolute velocity of an airship by knowing the speed at which two routes are covered, we have only to determine the geographical direction of the routes which we locate from a map, and the angles of routes as given by the compass, after correcting for the variation (the algebraical sum of the local magnetic declination and the deviation).
Date: June 1921
Creator: Volterra, Vito
Partner: UNT Libraries Government Documents Department

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,
Partner: UNT Libraries Government Documents Department

The Velocity Distribution Caused by an Airplane at the Points of a Vertical Plane Containing the Span

Description: "A formula for the computation of the vertical velocity component on all sides of an airplane is deduced and discussed. The formation is of value for the interpretation of such free flight tests where two airplanes fly alongside each other to facilitate observation" (p. 1).
Date: March 1925
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

Variation in Velocity Profile with Change in Surface Roughness of Boundary

Description: "The present report deals with the variation of a turbulent velocity profile in flow from rough to smooth wall and vice versa. Expressions obtained for the shear-stress distribution with respect to the distance from the point of junction of the different roughnesses and from the wall distance, are utilized to ascertain the developing velocity distributions. Under simplified assumptions, the use of these formulas renders possible the integration of the motion equations for the shear stress. This calculation is carried out and compared with the experiments" (p. 1).
Date: September 1940
Creator: Jacobs, W.
Partner: UNT Libraries Government Documents Department