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Aerodynamic Design of Axial-Flow Compressors, Volume 2

Description: Available experimental two-dimensional-cascade data for conventional compressor blade sections are correlated. The two-dimensional cascade and some of the principal aerodynamic factors involved in its operation are first briefly described. Then the data are analyzed by examining the variation of cascade performance at a reference incidence angle in the region of minimum loss. Variations of reference incidence angle, total-pressure loss, and deviation angle with cascade geometry, inlet Mach number, and Reynolds number are investigated. From the analysis and the correlations of the available data, rules and relations are evolved for the prediction of the magnitude of the reference total-pressure loss and the reference deviation and incidence angles for conventional blade profiles. These relations are developed in simplified forms readily applicable to compressor design procedures.
Date: August 1, 1956
Partner: UNT Libraries Government Documents Department

Factors Affecting the Starting Characteristics of Gas-Turbine Engines

Description: This report summarizes the effects of fuel volatility and engine design variables on the problem of starting gas-turbine engines at sea-level and altitude conditions. The starting operation for engines with tubular combustors is considered as three steps; namely, (1) ignition of a fuel-air mixture in the combustor, (2) propagation of flame through cross-fire tubes to all combustors, and (3) acceleration of the engine from windmilling or starting speed to the operating speed range. Pertinent data from laboratory researches, single-combustor studies, and full-scale engine investigations are presented on each phase of the starting problem.
Date: January 31, 1951
Partner: UNT Libraries Government Documents Department

Factors that affect operational reliability of turbojet engines

Description: The problem of improving operational reliability of turbojet engines is studied in a series of papers. Failure statistics for this engine are presented, the theory and experimental evidence on how engine failures occur are described, and the methods available for avoiding failure in operation are discussed. The individual papers of the series are Objectives, Failure Statistics, Foreign-Object Damage, Compressor Blades, Combustor Assembly, Nozzle Diaphrams, Turbine Buckets, Turbine Disks, Rolling Contact Bearings, Engine Fuel Controls, and Summary Discussion.
Date: January 31, 1956
Partner: UNT Libraries Government Documents Department

Chemical Action of Halogenated Agents in Fire Extinguishing

Description: From Summary: "The action of halogenated agents in preventing flame propagation in fuel-air mixtures in laboratory tests is discussed in terms of a possible chemical mechanism. The mechanism chosen is that of chain-breaking reactions between agent and active particles (hydrogen and oxygen atoms and hydroxyl radicsls). Data from the literature on the flammability peaks of n-heptane agent-air mixtures are treated. Ratings of agent effectiveness in terms of the fuel equivalent of the agent, based on both fuel and agent concentrations at the peak, are proposed as preferable to ratings in terms of agent concentration alone."
Date: September 1955
Creator: Belles, Frank E.
Partner: UNT Libraries Government Documents Department

Investigation of Icing Characteristics of Typical Light Airplane Engine Induction Systems

Description: The icing characteristics of two typical light-airplane engine induction systems were investigated using the carburetors and manifolds of engines in the horsepower ranges from 65 to 85 and 165 to 185. The smaller system consisted of a float-type carburetor with an unheated manifold and the larger system consisted of a single-barrel pressure-type carburetor with an oil-jacketed manifold. Carburetor-air temperature and humidity limits of visible and serious Icing were determined for various engine power conditions. Several.methods of achieving ice-free induction systems are discussed along with estimates of surface heating requirements of the various induct ion-system components. A study was also made of the icing characteristics of a typical light-airplane air scoop with an exposed filter and a modified system that provided a normal ram inlet with the filter located in a position to Induce inertia separation of the free water from the charge air. The principle of operation of float-type carburetors is proved to make them inherently more susceptible to icing at the throttle plate than pressure-type carburetors.. The results indicated that proper jacketing and heating of all parts exposed to the fuel spray can satisfactorily reduce or eliminate icing in the float-type carburetor and the manifold. Pressure-type carburetors can be protected from serious Icing by proper location of the fuel-discharge nozzle combined with suitable application of heat to critical parts.
Date: February 1, 1949
Creator: Coles, W. D.
Partner: UNT Libraries Government Documents Department

Interferometer corrections and measurements of laminar boundary layers in supersonic stream

Description: Report presenting an investigation of the laminar boundary layer on a flat plate in a supersonic stream by means of a Zehnder-Mach interferometer and a total-pressure probe. Results regarding the velocity and density profiles, skin friction, and recovery factor are provided.
Date: June 1950
Creator: Blue, Robert E.
Partner: UNT Libraries Government Documents Department

Investigation of Aerodynamic and Icing Characteristics of a Flush Alternate Inlet Induction System Air Scoop

Description: An investigation has been made in the NACA Lewis icing research tunnel to determine the aerodynamic and icing characteristics of a full-scale induction-system air-scoop assembly incorporating a flush alternate inlet. The flush inlet was located immediately downstream of the offset ram inlet and included a 180 deg reversal and a 90 deg elbow in the ducting between inlet and carburetor top deck. The model also had a preheat-air inlet. The investigation was made over a range of mass-air- flow ratios of 0 to 0.8, angles of attack of 0 and 4 deg airspeeds of 150 to 270 miles per hour, air temperatures of 0 and 25 F various liquid-water contents, and droplet sizes. The ram inlet gave good pressure recovery in both clear air and icing but rapid blockage of the top-deck screen occurred during icing. The flush alternate inlet had poor pressure recovery in both clear air and icing. The greatest decreases in the alternate-inlet pressure recovery were obtained at icing conditions of low air temperature and high liquid-water content. No serious screen icing was observed with the alternate inlet. Pressure and temperature distributions on the carburetor top deck were determined using the preheat-air supply with the preheat- and alternate-inlet doors in various positions. No screen icing occurred when the preheat-air system was operated in combination with alternate-inlet air flow.
Date: July 24, 1953
Creator: Lewis, James P.
Partner: UNT Libraries Government Documents Department

Investigation of Meteorological Conditions Associated with Aircraft Icing in Layer-Type Clouds for 1947-48 Winter

Description: Rotating-cylinder measurements of the icing conditions encountered in flight during the winter of 1947-48 are presented. Liquid water content, drop size, and temperature data are shown to be consistent with previously measured conditions and with proposed maximum icing conditions in supercooled layer-type clouds. Cumulative frequency graphs of meteorological parameters indicate the frequency with which various icing conditions have been encountered in the Great Lakes area and surrounding states.
Date: January 1949
Creator: Kline, Dwight B.
Partner: UNT Libraries Government Documents Department

Method of designing cascade blades with prescribed velocity distributions in compressible potential flows

Description: By use of the assumption that the pressure-volume relation is linear, a solution to the problem of designing a cascade for a given turning and with a prescribed velocity distribution along the blade in a potential flow of a compressible perfect fluid was obtained by a method of correspondence between potential flows of compressible and incompressible fluids. The designing of an isolated airfoil with a prescribed velocity distribution along the airfoil is considered as a special case of cascade. If the prescribed velocity distribution is not theoretically attainable, the method provides a means of modifying the distribution so as to obtain a physically significant blade shape. Numerical examples are included.
Date: October 1, 1949
Creator: Costello, George R.
Partner: UNT Libraries Government Documents Department

A method for the determination of aromatics in hydrocarbon mixtures

Description: Bulletin discusses a method to estimate aromatic hydrocarbons in hydrocarbon mixtures, which is important for determining the percentage of aromatics in fuel blends. The method was tested with nine base stocks at several levels of aromatics concentration and the maximum level of error was found to be about 0.5 percent. The speed and simplicity of the testing is emphasized.
Date: December 1945
Creator: Hipsher, Harold F.
Partner: UNT Libraries Government Documents Department

Experimental Permeability Measurements on a Strut-Supported Transpiration-Cooled Turbine Blade with Stainless-Steel Shell made by the Federal-Mogul Corporation under Bureau of Aeronautics Contract N0as 51613-C

Description: A turbine blade with a porous stainless-steel shell sintered to a supporting steel strut has been fabricated for tests at the NACA by Federal-Mogul Corporation under contract from the Bureau of Aeronautics, Department of the Navy. The apparent permeability of this blade, on the average, more nearly approaches the values specified by the NAGA than did two strut-supported bronze blades in a previous investigation. Random variations of permeability in the present blade are substantialy greater than those of the bronze blades, but projected improvements in certain phases of the fabrication process are expected to reduce these variations.
Date: April 30, 1954
Creator: Richards, Hadley T.
Partner: UNT Libraries Government Documents Department

Performance of a blunt-lip side inlet with ramp bleed, bypass, and a long constant-area duct ahead of the engine : Mach number 0.66 and 1.5 to 2.1

Description: Unsteady shock-induced separation of the ramp boundary layer was reduced and stabilized more effectively by external perforations than by external or internal slots. At Mach 2.0 peak total-pressure recovery was increased from 0.802 to 0.89 and stable mass-flow range was increased 185 percent over that for the solid ramp. Peak pressure recovery occurred just before instability. The 7 and one-third-diameter duct ahead of the engine reduced large total-pressure distortions but was not as successful for small distortions as obtained with throat bleed. By removing boundary-layer air the bypass nearly recovered the total-pressure loss due to the long duct.
Date: December 28, 1956
Creator: Allen, John L.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of effect on performance of dividing conical-spike nose inlets into halves at Mach numbers 1.5 to 2.0

Description: Inserting a splitter plate in the subsonic diffuser caused a pressure-recovery loss of about 1 percent for an inlet with a long nearly constant-area throat section. The loss was due to the increased surface area. Another inlet, which had a comparatively rapid area increase immediately after the throat, experienced pressure-recovery losses of 5 and 6 percent at Mach numbers of 1.8 and 2.0, respectively, and about 1 percent at Mach 1.5.
Date: December 19, 1955
Creator: Allen, John L.
Partner: UNT Libraries Government Documents Department

Effects of internal corner fillets on pressure recovery: Mass flow characteristics of scoop-type conical supersonic inlets

Description: Report presenting an investigation in the 8- by 6-foot supersonic tunnel at a range of free-stream Mach numbers at zero angle of attack to determine the effects of internal corner fillets on the pressure recovery characteristics of twin-scoop conical-type inlets utilizing boundary layer removal and mounted on the RM-10 body. Without boundary layer removal, the use of fillets resulted in substantial improvements in pressure recoveries and near critical mass flows up to a certain Mach number.
Date: December 8, 1952
Creator: Valerino, Alfred S.
Partner: UNT Libraries Government Documents Department

Performance characteristics at Mach numbers to 2.0 of various types of side inlets mounted on fuselage of proposed supersonic airplane 1: two-dimensional compression-ramp inlets with semicircular cowls

Description: Report presenting an experimental investigation to determine the performance of twin-scoop side inlets located on the fuselage of a proposed aircraft in a region of large boundary-layer thickness. Inlet configurations with subsonic and supersonic cowlings which utilized two-dimensional compression ramps and ram-type scoops for boundary-layer-removal systems were investigated at several Mach number ranges. Results regarding supersonic Mach number range, angle of attack, subsonic Mach number, and static conditions are provided.
Date: July 16, 1952
Creator: Valerino, Alfred S.
Partner: UNT Libraries Government Documents Department

Performance of supersonic ramp-type side inlet with combinations of fuselage and inlet throat boundary-layer removal

Description: Report presenting an experimental investigation to evaluate combinations of fuselage and inlet throat boundary-layer removal for a ramp-type side inlet in the 8- by 6-foot supersonic wind tunnel at Mach numbers 1.5, 1.8, and 2.0. Optimum combinations of fuselage and inlet throat boundary-layer removal showed gains in available thrust from 3 to 10 percent over the case of no inlet throat bleed. Results regarding variations of diffuser total-pressure distortion, recovery and external drag coefficients, and net gains in available thrust are provided.
Date: April 25, 1956
Creator: Campbell, Robert C.
Partner: UNT Libraries Government Documents Department

Performance of an Inlet Having a Variable-angle Two-dimensional Compression Surface and a Fixed-geometry Subsonic Diffuser for Application to Reduced Engine Rotative Speeds- Mach Numbers 0.66, 1.5, 1.7, and 2.0

Description: Report presenting the performance of a two-dimensional side inlet with a technique of varying compression-surface angle while retaining a fixed-geometry diffuser at several Mach numbers and zero angle of attack. A 12 degree compression ramp was faired into the diffuser contour in this conventional manner. Results regarding the inlet flow field, application to reduced engine speeds, and a inlet performance with a sudden expansion in the diffuser are provided.
Date: January 30, 1958
Creator: Allen, John L.
Partner: UNT Libraries Government Documents Department

Performance of mixed-flow impeller, model MFI-1B, with diffuser vanes at equivalent impeller speeds from 1100 to 1700 feet per second

Description: Report presenting an investigation of the performance characteristics of a mixed-flow impeller (Model MFI-1B) in combination with a vaned diffuser. The results indicated that the peak pressure ratio and maximum efficiency were not being obtained at overdesign speeds because of premature surge. Increasing inlet angle at the leading edge of the vanes improved the pressure ratio and efficiency at overdesign speeds with little to no effect on underdesign speeds.
Date: June 16, 1954
Creator: Osborn, Walter M.
Partner: UNT Libraries Government Documents Department

Jet effects on pressure loading of all-movable horizontal stabilizer

Description: Report presenting an investigation in the 8- by 6-foot supersonic tunnel to determine the effects of a cold exhaust jet on the pressure loadings of an all-movable, 45 degree sweptback horizontal stabilizer located in a region influenced by the jet. Results indicated that at jet pressure ratios of 1 to 9, the exhaust jet did not appreciably affect the pressure loadings of the stabilizer.
Date: June 10, 1954
Creator: Valerino, Alfred S.
Partner: UNT Libraries Government Documents Department

Preliminary Results of Heat Transfer from a Stationary and Rotating Ellipsoidal Spinner

Description: Convective heat-transfer coefficients in dry air were obtained for an ellipsoidal spinner of 30-inch maximum diameter for both stationary and rotating operation over a range of conditions including airspeeds up to 275 miles per hour, rotational speeds up to 1200 rpm, and angles of attack of zero and 40 The results are presented in terms of Nusselt numbers, Reynolds numbers, and convective heat-transfer coefficients. The studies included both uniform heating densities over the spinner and uniform surface temperatures.. In general, the results showed that rotation will increase the convective heat transfer from a spinner, especially in the turbulent-flow regions. Rotation of the spinner at 1200 rpm and at a free-stream velocity of 275 miles per hour increased the Nusselt number parameter in the turbulent-flow region by 32 percent over that obtained with a stationary spinner; whereas in the nose region, where the flow was laminar, an increase of only 18 percent was observed. Transition from laminar to turbulent flow occurred over a large range of Reynolds numbers primarily because of surface roughness of the spinner. Operation at an angle of attack of 40 had only small effects on the local convective heat transfer for the model studied.
Date: August 6, 1953
Creator: von Glahn, U.
Partner: UNT Libraries Government Documents Department

A preliminary investigation at Mach number 1.91 of a diffuser employing a pivoted cone to improve operation at angle of attack

Description: Report presenting an investigation to determine the performance of a conical-nose supersonic diffuser at angle of attack. The inlet had a pivoting cone which could be oriented to any of several angles independent of the angle of attack of the diffuser. Results regarding total-pressure recovery and mass-flow characteristics, cowl lip position, cone position relative to angle of attack, shadowgraphs, and contour maps are provided.
Date: December 8, 1953
Creator: Beheim, Milton A.
Partner: UNT Libraries Government Documents Department