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An Estimate of the Fluctuating Surface Pressures Encountered in the Reentry of a Ballistic Missile

Description: Note presenting calculations made of the magnitude of the surface sound pressure levels that will occur on blunt-nosed vehicles during reentry into the earth's atmosphere. The results presented cover a wide range of re-entrance velocities and reentrance angles into the atmosphere and sizes and weights of the vehicle.
Date: July 1958
Creator: Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

Investigation of far noise field of jets 2: comparison of air jets and jet engines

Description: Report presenting a comparison of the noise generation of air jets and turbojet engines under similar free-flight conditions. Results regarding a comparison of the sound power, afterburner data, spectrum measurements, noise data for engine thrust, and frequency distribution for the two engines are provided.
Date: January 1956
Creator: Coles, Willard D. & Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

A Method for Rapid Determination of the Icing Limit of a Body in Terms of the Stream Conditions

Description: 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.
Date: March 1953
Creator: Callaghan, Edmund E. & Serafini, John S.
Partner: UNT Libraries Government Documents Department

Analytical Investigation of Icing Limit for Diamond-Shaped Airfoil in Transonic and Supersonic Flow

Description: Calculations have been made for the icing limit of a diamond airfoil at zero angle of attack in terms of the stream Mach number, stream temperature, and pressure altitude. The icing limit is defined as a wetted-surface temperature of 320 F and is related to the stream conditions by the method of Hardy. The results show that the point most likely to ice on the airfoil lies immediately behind the shoulder and is subject to possible icing at Mach numbers as high as 1.4.
Date: January 1953
Creator: Callaghan, Edmund E. & Serafini, John S.
Partner: UNT Libraries Government Documents Department

Investigation of flow coefficient of circular, square, and elliptical orifices at high pressure ratios

Description: Report presenting an experimental investigation to determine the orifice coefficient of a jet direct 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.
Date: September 1949
Creator: Callaghan, Edmund E. & Bowden, Dean T.
Partner: UNT Libraries Government Documents Department

Analytical investigation of icing limit for diamond-shaped airfoil in transonic and supersonic flow

Description: From Introduction: "The results presented herein were calculated for a symmetrical diamond airfoil at zero angle of attack for a range of airfoil-thickness ratios from 0.02 to 0.10, pressure altitude from sea level to 45,000 feet, and free-stream static temperatures to -.40^o F."
Date: January 1953
Creator: Callaghan, Edmund E. & Serafini, John S.
Partner: UNT Libraries Government Documents Department

Experimental investigation of hot-gas bleedback for ice protection of turbojet engines 2: nacelle with long straight air inlet

Description: Report presenting aerodynamic and icing investigations conducted in the icing research tunnel on a model of a turbojet-engine nacelle with a long straight air inlet in order to provide basic design criteria for hot-gas blowback systems. The most uniform temperature distribution was obtained with a bleedback of 4.4 percent at a gas temperature of 1000 degrees Fahrenheit and resulted in an average dry-air-temperature rise of 46 degrees Fahrenheit.
Date: May 26, 1949
Creator: Callaghan, Edmund E. & Ruggeri, Robert S.
Partner: UNT Libraries Government Documents Department

Experimental investigation of hot-gas bleedback for ice protection of turbojet engines 3: nacelle with short straight air inlet

Description: Report presenting aerodynamic and icing investigations in the icing research tunnel on a model of a turbojet-engine nacelle with a short straight air inlet. The hot-gas blowback system consisted of several orifices peripherally located around the inlet and was investigated in both dry-air and icing conditions. Results regarding the aerodynamic investigation without bleedback, aerodynamic investigation with cold-gas bleedback, aerodynamic investigation with hot-gas bleedback, and icing with bleedback are provided.
Date: August 4, 1949
Creator: Ruggeri, Robert S. & Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

Full-Scale Investigation of Several Jet-Engine Noise-Reduction Nozzles

Description: A number of nozzles which use the mixing interference of adjacent jets for noise suppression were investigated. Reductions in sound power of nearly 70 percent (5 db) with thrust losses of 1 percent were achieved. A method of calculating the limiting frequency affected by this type of suppression nozzle, that is , multiple-slot nozzles, is presented. Data are shown which indicate that further large reductions in sound power are not likely with mixing-interference nozzles.
Date: April 1, 1957
Creator: Coles, Willard D. & Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

Full-Scale Investigation of Several Jet-Engine Noise-Reduction Nozzles

Description: A number of noise-suppression nozzles were tested on full-scale engines. In general, these nozzles achieved noise reduction by the mixing interference of adjacent jets, that is, by using multiple-slot-nozzles. Several of the nozzles achieved reductions in sound power of approximately 5 decibels (nearly 70 percent) with small thrust losses (approx. 1 percent). The maximum sound-pressure level was reduced by as much as 18 decibels in particular frequency bands. Some of the nozzles showed considerable spatial asymmetry; that is, the sound field was not rotationally symmetrical. A method of calculating the limiting frequency effected by such nozzles is presented. Furthermore data are shown that appear to indicate that further reductions in sound power will not be easily achieved from nozzles using mixing interference as a means of noise suppression.
Date: January 1, 1958
Creator: Coles, Willard D. & Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

Far Noise Field of Air Jets and Jet Engines

Description: An experimental investigation was conducted to study and compare the acoustic radiation of air jets and jet engines. A number of different nozzle-exit shapes were studied with air jets to determine the effect of exit shape on noise generation. Circular, square, rectangular, and elliptical convergent nozzles and convergent-divergent and plug nozzles were investigated. The spectral distributions of the sound power for the engine and the air jet were in good agreement for the case where the engine data were not greatly affected by reflection or jet interference effects. Such power spectra for a subsonic or slightly choked engine or air jet show that the peaks of the spectra occur at a Strouhal number of 0.3.
Date: January 1, 1957
Creator: Callaghan, Edmund E. & Coles, Willard D.
Partner: UNT Libraries Government Documents Department

Investigation of the Penetration on an Air Jet Directed Perpendicularly to an Air Stream

Description: Note presenting an experimental investigation conducted to determine the penetration of a circular air jet directly 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.
Partner: UNT Libraries Government Documents Department

Investigation of Flow Coefficient of Circular, Square, and Elliptical Orifices at High Pressure Ratios

Description: 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.
Partner: UNT Libraries Government Documents Department

Near Noise Field of a Jet-Engine Exhaust

Description: From Summary: "Aircraft structures located in the near noise field of a jet engine are subjected to extremely high fluctuating pressures that may cause structural fatigue. Studies of such structures have been limited by lack of knowledge of the loadings involved. The acoustic near field produced by the exhaust of a stationary turbojet engine having a high pressure ratio was measured for a single operating condition without burning. The maximum overall sound pressure without afterburning was found to be about 42 pounds per square foot along the jet boundary in the region immediately downstream of the jet-nozzle exit."
Date: 1957
Creator: Howes, Walton L.; Callaghan, Edmund E.; Coles, Willard D. & Mull, Harold R.
Partner: UNT Libraries Government Documents Department

NACA Investigations of Icing-Protection Systems for Turbojet-Engine Installations

Description: Investigations have been made in flight and in wind tunnels to determine which components of turbojet installations are most critical in icing conditions, and to evaluate several methods of icing protection. From these studies, the requirements necessary for adequate icing protection and the consequent penalties on engine performance can be estimated. Because investigations have indicated that the compressor-inlet screen constitutes the greatest icing hazard and is difficult to protect, complete removal or retraction of the screen upon encountering an icing condition is recommended. In the absence of the screen, the inlet guide vanes of an axial-flow-type turbojet engine constitute the greatest danger to engine operation in an icing condition; a centrifugal-type engine, on the other hand, is relatively unsusceptible to icing once the screen has been removed. Of the three icing-protection systems investigated, surface heating, hot-gas bleedback, and inertia-separation inlets, only the first two offer an acceptable solution to the problem of engine icing protection. Surface heating, either by gas heating or electrical means, appears to be the most acceptable icing-protection method with regard to performance losses. Hot-gas bleedback, although causing undesirable thrust losses, offers an easy means of obtaining icing protection for some installations. The final choice of an icing-protection system depends, however, on the supply of heated gas and electrical power available and on the allowable performance and. weight penalties associated with each system.
Date: May 2, 1951
Creator: VonGlahn, Uwe; Callaghan, Edmund E. & Gray, Vernon H.
Partner: UNT Libraries Government Documents Department

Investigation of noise field and velocity profiles of an afterburning engine

Description: Report presenting sound pressure levels, frequency spectrum, and jet velocity profiles for an engine-afterburner combination at various values of afterburner fuel-air ratio. Lower sound pressure levels were obtained from a current fighter aircraft with a different afterburner configuration. Results regarding the jet temperature, jet Mach number and velocity, and sound measurements are provided.
Date: September 24, 1954
Creator: North, Warren J.; Callaghan, Edmund E. & Lanzo, Chester D.
Partner: UNT Libraries Government Documents Department

Investigation of Noise Field and Velocity Profiles of an Afterburning Engine

Description: From Summary: "Sound pressure levels, frequency spectrum, and jet velocity profiles are presented for an engine-afterburner combination at various values of afterburner fuel - air ratio. At the high fuel-air ratios, severe low-frequency resonance was encountered which represented more than half the total energy in the sound spectrum. At similar thrust conditions, lower sound pressure levels were obtained from a current fighter air craft with a different afterburner configuration. The lower sound pressure levels are attributed to resonance-free afterburner operation and thereby indicate the importance of acoustic considerations in afterburner design."
Date: September 24, 1954
Creator: North, Warren J.; Callaghan, Edmund E. & Lanzo, Chester D.
Partner: UNT Libraries Government Documents Department

Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream

Description: 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.
Partner: UNT Libraries Government Documents Department

Experimental investigation of hot-gas bleedback for ice protection of turbojet engines 1: nacelle with offset air inlet

Description: Report presenting aerodynamic and icing investigations on a model of a turbojet-engine nacelle in order to provide icing protection for the engine, protective screen, and accessory housing by the introduction of hot gases into the inlet-air stream. Adequate ice protection was afforded when the minimum kinetic temperature in the protective screen was greater than 32 degrees Fahrenheit.
Date: July 9, 1948
Creator: Callaghan, Edmund E.; Ruggeri, Robert S. & Krebs, Richard P.
Partner: UNT Libraries Government Documents Department

Near noise field of a jet-engine exhaust 2: cross correlation of sound pressures

Description: Pressure cross correlations were obtained over a range of jet velocities both longitudinally and laterally for the overall sound pressure and for several frequency bands. The region of positive correlation was found to increase with distance downstream of the nozzle exit and was greater for lateral than for longitudinal correlations. In general, little change in the correlation curves was found as a function of jet velocity or frequency band width. Measurements made with a fixed and a movable microphone in a plate showed correlations similar to the free-field results. The results are interpreted in terms of pressure loads on surfaces.
Date: September 1956
Creator: Callaghan, Edmund E.; Howes, Walton L. & Coles, Willard D.
Partner: UNT Libraries Government Documents Department