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4,107 Matching Results
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Impingement of Water Droplets on a Cylinder in an Incompressible Flow Field and Evaluation of Rotating Multicylinder Method for Measurement of Droplet-Size Distribution, Volume-Median Droplet-Size, and Liquid-Water Content in Clouds
Note presenting an evaluation of the rotating method for the measurement of droplet-size distribution, volume-median droplet size, and liquid-water content in clouds, which showed that small uncertainties in basic data eliminate the distinction between cloud droplet-size distributions and are a source of large errors in the determination of the droplet size. Matching curves for obtaining droplet-size distribution, volume-median droplet size, and liquid-water content from flight data were computed from the results of the droplet-trajectory calculations.
Date:
March 1953
Creator:
Brun, Rinaldo J. & Mergler, Harry W.
System:
The UNT Digital Library
Impingement of Cloud Droplets on Aerodynamic Bodies as Affected by Compressibility of Air Flow Around the Body
Note presenting the computation of the trajectories of water droplets in a compressible-air flow field around a cylinder using a mechanical analog. The results of the calculations at approximately the flight critical Mach number were compared with calculations of trajectories in an incompressible flow field. Results regarding the extension of cylinder results to airfoils are provided.
Date:
March 1953
Creator:
Brun, Rinaldo J.; Serafini, John S. & Gallagher, Helen M.
System:
The UNT Digital Library
A Method for Determining Cloud-Droplet Impingement on Swept Wings
From Summary: "The general effect of wing sweep on cloud-droplet trajectories about swept wings of high aspect ratio moving at subsonic speeds is discussed. A method of computing droplet trajectories about yawed cylinders and swept wings is presented, and illustrative droplet trajectories are computed. A method of extending two-dimensional calculations of droplet impingement on nonswept wings to swept wings is presented."
Date:
April 1953
Creator:
Dorsch, Robert G. & Brun, Rinaldo J.
System:
The UNT Digital Library
Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 5 in Axisymmetric Flow
"The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 5 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, (3) distribution of impinging water, and (4) local rate of water impingement" (p. 1).
Date:
March 1954
Creator:
Dorsch, Robert G.; Brun, Rinaldo J. & Gregg, John L.
System:
The UNT Digital Library
Variation of Local Liquid-Water Concentration About and Ellipsoid of Fineness Ratio 5 Moving in a Droplet Field
From Summary: "Trajectories of water droplets about an ellipsoid of revolution with a fineness ratio of 5 (which often approximates the shape of an aircraft fuselage or missile) were computed with the aid of a differential analyzer. Analyses of these trajectories indicate that the local concentration of liquid water at various points about an ellipsoid in flight through a droplet field varies considerably and under some conditions may be several times the free-stream concentration."
Date:
July 1954
Creator:
Dorsch, Robert G. & Brun, Rinaldo J.
System:
The UNT Digital Library
Analogy Between Mass and Heat Transfer with Turbulent Flow
From Introduction: "The purpose of this paper is to present an analysis of the mass- and heat-transfer process in terms of a simplified physical picture of the turbulent boundary layer subject to the assumptions previously described."
Date:
October 1953
Creator:
Callaghan, Edmund E.
System:
The UNT Digital Library
Experimental Investigation of Sublimation of Ice at Subsonic and Supersonic Speeds and Its Relation to Heat Transfer
"An experimental investigation was conducted in a 3.84- by 10-inch tunnel to determine the mass transfer by sublimation, heat transfer, and skin friction for an iced surface on a flat plate for Mach numbers of 0.4, 0.6, and 0.8 and pressure altitudes to 30,000 feet. Measurements of rates of sublimation were also made for a Mach number of 1.3 at a pressure altitude of 30,000 feet. The results show that the parameters of sublimation and heat transfer were 40 to 50 percent greater for an iced surface than was the bare-plate heat-transfer parameter" (p. 1).
Date:
March 1954
Creator:
Coles, Willard D. & Ruggeri, Robert S.
System:
The UNT Digital Library
The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity
"Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure of the liquid-water content of the cloud" (p. 1).
Date:
January 1952
Creator:
Neel, Carr B. & Steinmetz, Charles P.
System:
The UNT Digital Library
An Instrument Employing a Coronal Discharge for the Determination of Droplet-Size Distribution in Clouds
From Summary: "A flight instrument that uses electric means for measuring the droplet-size distribution in above-freezing clouds has been devised and given preliminary evaluation in flight. An electric charge is placed on the droplets and they are separated aerodynamically according to their mass. Because the charge placed on the droplets is a. function of the droplet size, the size spectrum can 'be determined by measurement of the charge deposited on cylinders of several different sizes placed to intercept the charged droplets. An expression for the rate of charge acquisition by a water droplet in a field of coronal discharge is derived."
Date:
September 1951
Creator:
Brun, Rinaldo J.; Levine, Joseph & Kleinknecht, Kenneth S.
System:
The UNT Digital Library
Comparison of Three Multicylinder Icing Meters and Critique of Multicylinder Method
"Three multicylinder cloud meters, fundamentally similar but differing in important details, were compared in use at the Mount Washington Observatory. Determinations of liquid water content were found to agree within the limits of the probable error, but the two instruments designed by the National Advisory Committee for Aeronautics indicated larger drop sizes than did the Observatory's instrument, apparently because of spurious ice catch on the rather rough surface of the larger cylinders. Comparisons of drop-size distribution were largely indeterminate" (p. 1).
Date:
June 1952
Creator:
Howell, Wallace E.
System:
The UNT Digital Library
An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size Distributions in Flight
"An airborne cloud aeroscope by which droplet size, size distribution, and liquid-water content of clouds can be determined has been developed and tested in flight and in wind tunnels with water sprays. In this aeroscope the cloud droplets are continuously captured in a stream of oil, which Is then photographed by a photomicrographic camera. The droplet size and size distribution can be determined directly from the photographs" (p. 1).
Date:
January 1956
Creator:
Hacker, Paul T.
System:
The UNT Digital Library
A Probability Analysis of the Meteorological Factors Conducive to Aircraft Icing in the United States
Note presenting meteorological icing data obtianed in flight in the United States that is analyzed statistically and used to develop methods for the determination of the various simultaneous combinations of the three basic icing parameters and the probability of exceeding any specified group of values of liquid-water content associated simultaneously with temperature and drop-diameter values. A mathematical basis is also provided for the future statistical analysis of meteorological icing data that can be obtained throughout the world.
Date:
July 1952
Creator:
Lewis, William & Bergrun, Norman R.
System:
The UNT Digital Library
Comparison of Heat Transfer from Airfoil in Natural and Simulated Icing Conditions
"An investigation of the heat transfer from an airfoil in clear air and in simulated icing conditions was conducted in the NACA Lewis 6- by 9-foot icing-research tunnel in order to determine the validity of heat-transfer data as obtained in the tunnel. This investigation was made on the same model NACA 65,2-016 airfoil section used in a previous flight study, under similar heating, icing, and operating conditions. The effect of tunnel turbulence, in clear air and in icing was indicated by the forward movement of transition from laminar to turbulent heat transfer" (p. 1).
Date:
September 1951
Creator:
Gelder, Thomas F. & Lewis, James P.
System:
The UNT Digital Library
A Method for Rapid Determination of the Icing Limit of a Body in Terms of the Stream Conditions
"The effects of existing frictional heating were analyzed to determine the conditions under which ice formations on aircraft surfaces can be prevented. A method is presented for rapidly determining by means of charts the combination of-Mach number, altitude, and stream temperature which will maintain an ice-free surface in an icing cloud. The method can be applied to both subsonic and supersonic flow. The charts presented are for Mach numbers up to 1.8 and pressure altitudes from sea level to 45,000 feet" (p. 1).
Date:
March 1953
Creator:
Callaghan, Edmund E. & Serafini, John S.
System:
The UNT Digital Library
Investigation of the Penetration of an Air Jet Directed Perpendicularly to an Air Stream
Note presenting an experimental investigation to determine the penetration of a circular air jet directed perpendicularly to an air stream as a function of jet density, jet velocity, air-stream density, air-stream velocity, jet diameter, and distance downstream from the jet. The penetration was determined for nearly constant values of air-stream density at two tunnel velocities, four jet diameters, four positions downstream of the jet, and for a large range of jet velocities and densities.
Date:
June 1948
Creator:
Callaghan, Edmund E. & Ruggeri, Robert S.
System:
The UNT Digital Library
Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream
From Summary: "An experimental investigation was conducted to determine the penetration of air jets directed perpendicularly to an air stream. Jets issuing from circular, square, and elliptical orifices were investigated and the jet penetration at a position downstream of the orifice was determined- as a function of jet density, jet velocity, air-stream density, air-stream velocity, effective jet diameter, and orifice flow coeffIcient. The jet penetrations were determined for nearly constant values of air-stream density at three tunnel-air velocities arid for a large range of jet velocities and densities."
Date:
February 1950
Creator:
Ruggeri, Robert S.; Callaghan, Edmund E. & Bowden, Dean T.
System:
The UNT Digital Library
Investigation of Flow Coefficient of Circular, Square, and Elliptical Orifices at High Pressure Ratios
Note presenting an experimental investigation conducted to determine the orifice coefficient of a jet directed perpendicularly to an air stream as a function of pressure ratio and jet Reynolds number for circular, square, and elliptical orifices. The effect of air-stream velocity on the jet flow was also determined for three tunnel-air velocities. Results regarding jets discharging into still air and effect of tunnel-air velocity on jet flow.
Date:
September 1949
Creator:
Callaghan, Edmund E. & Bowden, Dean T.
System:
The UNT Digital Library
General Correlation of Temperature Profiles Downstream of a Heated Air Jet Directed at Various Angles to Air Stream
An experimental investigation was conducted to determine the temperature profiles downstream of heated air jets directed at angles of 90 deg, 60 deg, 45 deg, and 30 deg to an air stream. The profiles were determined at two positions downstream of the jet as a function of jet diameter, jet density, jet velocity, free-stream density, free-stream velocity, jet total temperature, orifice flow coefficient, and jet angle. A method is presented which yields a good approximation of the temperature profile in terms of the flow and geometric conditions.
Date:
December 1952
Creator:
Ruggeri, Robert S.
System:
The UNT Digital Library
A General Correlation of Temperature Profiles Downstream of a Heated-Air Jet Directed Perpendicularly to an Air Stream
"An experimental investigation was conducted to determine the temperature profile downstream of a heated-air jet directed perpendicularly to an air stream. The profiles were determined at several positions downstream of the jet as functions of jet density, jet velocity, free-stream density, free-stream velocity, jet temperature, and orifice flow coefficient. A method is presented which yields a good approximation of the temperature profile in terms of dimensionless parameters of the flow and geometric conditions" (p. 1).
Date:
September 1951
Creator:
Callaghan, Edmund E. & Ruggeri, Robert S.
System:
The UNT Digital Library
Simple Graphical Solution of Heat Transfer and Evaporation From Surface Heated to Prevent Icing
"Equations expressing the heat transfer and evaporation from wetted surfaces during ice prevention have been simplified and regrouped to permit solutions by simple graphical means. Working charts for quick and accurate anti-icing calculations are also included" (p. 1).
Date:
October 1952
Creator:
Gray, Vernon H.
System:
The UNT Digital Library
Theoretical Investigation of Submerged Inlets at Low Speeds
From Summary: "The general characteristics of the flow field in a submerged air inlet are investigated by theoretical, wind-tunnel, and visual-flow studies. Equations are developed for calculating the laminar and turbulent boundary-layer growth along the ramp floor for parallel, divergent, and convergent ramp walls, and a general equation is derived relating the boundary-layer pressure losses to the boundary-layer thickness. It is demonstrated that the growth of the boundary layer on the floor of the divergent-ramp inlet is retarded and that a vortex pair is generated in such an inlet."
Date:
August 1951
Creator:
Sacks, Alvin H. & Spreiter, John R.
System:
The UNT Digital Library
Aerodynamic forces, moments, and stability derivatives for slender bodies of general cross section
From Introduction: "The present paper employs an approach believed to be novel in slender-body theory and is concerned with developing formulas for the forces and moments as well as the stability derivatives for general slender wing-body combinations."
Date:
November 1954
Creator:
Sacks, Alvin H.
System:
The UNT Digital Library
Hydrodynamic and Aerodynamic Tests of a Family of Models of Seaplane Floats With Varying Angles of Dead Rise: N.A.C.A. Models 57-A, 57-B, and 57-C
Report presenting testing of three models of V-bottom floats for twin-float seaplanes with varying angles of dead rise were tested in a tank and a wind tunnel. Results regarding the effect of angle of dead rise, height and amount of spray at hump speed, aerodynamic drag, effect of cross-sectional shape and load coefficients, and spray strips are provided.
Date:
July 1939
Creator:
Parkinson, John B.; Olson, Roland E. & House, Rufus O.
System:
The UNT Digital Library
A Simple Method of Estimating the Subsonic Lift and Damping in Roll of Sweptback Wings
"A method of modifying existing correction factors of lifting-surface theory to account approximately for the effects of sweep was derived, and these factors were applied to existing lifting-line theories for the lift and damping in roll of swept wings. Despite the simplicity of the resulting formulas the agreement with experimental data for low speeds is very good. The equation for lift is expressed entirely in terms of the geometric characteristics of the wing and the section-lift-curve; the necessity for any charts is thereby eliminated" (p. 1).
Date:
April 1949
Creator:
Polhamus, Edward C.
System:
The UNT Digital Library