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Design and test of mixed-flow impellers 5: design procedure and performance results for two vaned diffusers tested with impeller model MFI-1B

Description: Report presenting the design procedure and experimental test results for a range of impeller speeds for two vaned diffusers of 24 and 40 vanes. Both sets of vanes were designed to give approximately the same prescribed velocity distribution on the vane surfaces and were tested with the same impeller. Results regarding overall performance and the total-pressure-loss coefficient for both vanes are provided.
Date: July 7, 1955
Creator: Hamrick, Joseph T. & Osborn, Walter M.
Partner: UNT Libraries Government Documents Department

Experimental Study of Effect of Vaneless-Diffuser Diameter on Diffuser Performance

Description: Report presenting an investigation of the diameter of vaneless diffusers and how it affects the variations in compressor and diffuser efficiency. The primary efficiency losses occurred in the vicinity of the diffuser entrance and exit. The effect of diffuser diameter was very slight on nearly all characteristics studied.
Date: October 1948
Creator: Bradshaw, Guy R. & Laskin, Eugene B.
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of Supersonic Diffusers

Description: Report presenting the deceleration of air from supersonic velocities in channels. A normal shock in the diverging part of the diffuser is probably necessary for stable flow, and ways of minimizing the intensity of this shock have been developed.
Date: May 1945
Creator: Kantrowitz, Arthur & Donaldson, Coleman duP.
Partner: UNT Libraries Government Documents Department

The Performance of a Vaneless Diffuser Fan

Description: "The present paper is devoted to the theoretical and experimental investigation of one of the stationary elements of a fan, namely, the vaneless diffuser. The method of computation is based on the principles developed by Pfleiderer (Forschungsarbeiten No. 295). The practical interest of this investigation arises from the fact that the design of the fan guide elements - vaneless diffusers, guide vanes, spiral casing - is far behind the design of the impeller as regards accuracy and reliability" (p. 1).
Date: December 1942
Creator: Polikovsky, V. & Nevelson, M.
Partner: UNT Libraries Government Documents Department

Summary of Subsonic-Diffuser Data

Description: Memorandum presenting a review of the subsonic-diffuser data available in the literature, which is then reduced to certain appropriate performance coefficients and presented as functions of the significant geometric and flow variables. Results regarding total-pressure-loss factor, diffuser effectiveness, recovery of diffuser effectiveness in the tailpipe, inlet speed effects, exit flow distributions, boundary-layer control, and effects of distorted inlet velocity distribution are provided.
Date: October 12, 1956
Creator: Henry, John R.; Wood, Charles C. & Wilbur, Stafford W.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of cone-type diffusers designed for minimum spillage at inlet

Description: Report presenting a preliminary investigation of cone-type diffusers designed for minimum spillage at the inlet during operation in the supersonic tunnel at Mach number 1.85. Pressure recoveries of a series of stationary cones with included angles from 20 degrees to 60 degrees were investigated. Results regarding the pressure recovery with stationary cones and pressure recovery of movable-cone configurations are provided.
Date: May 3, 1948
Creator: Luidens, Roger W. & Hunczak, Henry
Partner: UNT Libraries Government Documents Department

Effect of Various Arrangements of Triangular Ledges on the Performance of a 23 Degree Conical Diffuser at Subsonic Mach Numbers

Description: Note presenting an investigation to determine whether the use of annular ledges to promote turbulent momentum exchange will improve the performance of a short, wide-angle diffuser. Results are presented of tests of a 23 degree conical diffuser with a 2:1 ratio of exit to inlet area with both rough and smooth triangular ledges, approximately one-tenth of the inlet boundary-layer thickness in height, installed in succession from the inlet to the exit. Results regarding rough ledges, comparison between smooth and rough ledges, and effect of changing the height of the smooth ledge are provided.
Date: January 1954
Creator: Persh, Jerome & Bailey, Bruce M.
Partner: UNT Libraries Government Documents Department

Investigation of the effect of short fixed diffusers on starting blowdown jets in the Mach number range from 2.7 to 4.5

Description: Report presenting an investigation at several Mach numbers to determine the effect of short fixed convergent-divergent wedge diffusers on the starting characteristics of blowdown jets exhausting to the atmosphere. Results regarding the boundary-layer separation on nozzle contour, results of the testing, and analysis of flow during the starting process are provided.
Date: January 1956
Creator: Moore, John A.
Partner: UNT Libraries Government Documents Department

Method of designing vaneless diffusers and experimental investigation of certain undetermined parameters

Description: Report presenting a method of designing vaneless diffusers using data given for simple conical diffusers. A family of diffusers with three different cone angles and the same throat height was designed and experimentally studied. A second set of diffusers with varying throats with the best cone angle was also investigated.
Date: September 1947
Creator: Brown, W. Byron & Bradshaw, Guy R.
Partner: UNT Libraries Government Documents Department

Analytical Investigation of Ram-Jet-Engine Performance in Flight Mach Number Range From 3 to 7

Description: "An analytical investigation was made of the performance of isolated ram-jet engines in the flight Mach number range from 3 to 7 for two types of diffuser, a high-efficiency diffuser, and a normal-shock diffuser. The fuel was assumed to be a hydrocarbon similar to gasoline. The conclusions reached are: (1) a design altitude of about 100,000 feet is desirable for a high-efficiency high Mach number ram jet on the basis of engine construction and performance; and (2) although greater thrust could be obtained with other fuels, gasoline provides sufficient energy release for maximum engine efficiency in the flight Mach number range investigated. The maximum engine efficiency calculated was 0.47, which occurred at a Mach number of 5. At a Mach number of 7, the maximum propulsive-thrust coefficient was 0.57" (p. 1).
Date: October 17, 1951
Creator: Evans, Philip J., Jr.
Partner: UNT Libraries Government Documents Department

Investigation of Suction-Slot Shapes for Controlling a Turbulent Boundary Layer

Description: Note presenting tests of three types of boundary-layer-control suction slots in a two-dimensional diffuser to investigate design criterions and to evaluate the practical minimum total-pressure losses. Testing occurred at a velocity of about 100 feet per second with a boundary layer with a displacement thickness of 0.85 inch and a shape parameter of about 1.8.
Date: June 1947
Creator: Pierpont, P. Kenneth
Partner: UNT Libraries Government Documents Department

Investigations of an Annular Diffuser-Fan Combination Handling Rotating Flow

Description: Memorandum presenting an investigation of two annular diffusers of different conical angles of expansion but constant outer diameters with rotating flow behind a fan. The performance characteristics are determined and the rotational-kinetic-energy effects on the overall energy transformation are observed over a range of inlet mach numbers from 0.1 to 0.44 and angles of flow up to 28 degrees.
Date: April 25, 1949
Creator: Schwartz, Ira R.
Partner: UNT Libraries Government Documents Department

Friction Coefficients in a Vaneless Diffuser

Description: Note presenting a determination of friction coefficients for three constant-area vaneless diffusers, used in conjunction with a centrifugal impeller, from static- and total-pressure surveys taken at several radii and from the usual overall measurements of temperature, pressure, and air flow. The average value of the friction coefficient through the entire diffuser was approximately 50 percent higher than that for fully developed turbulent flow in smooth pipes.
Date: May 1947
Creator: Brown, W. Byron
Partner: UNT Libraries Government Documents Department

Full-Scale Free-Jet Investigation of a Two-Shock Side-Inlet Diffuser at Mach 2.75 and a Comparison With a Single-Shock Diffuser

Description: Memorandum presenting a full-scale free-jet investigation of a two-shock side-inlet diffuser at Mach umber 2.75 in an altitude test chamber. Data were obtained over ranges of free-stream total pressure and temperature. Results regarding diffuser mass-flow ratio, critical pressure recovery, diffuser static-pressure variation, and diffuser-outlet flow conditions are provided.
Date: April 24, 1957
Creator: McAulay, John E.
Partner: UNT Libraries Government Documents Department

Effect of Screens in Wide-Angle Diffusers

Description: Note presenting an experimental investigation at low airspeeds of the filling effect observed when a screen or similar resistance is placed across a diffuser. The filling effect is found to be real in that screens can prevent separation or restore separated flow in diffusers even of extreme divergence and to depend principally on screen location and pressure-drop coefficient of the screen.
Date: July 1948
Creator: Schubauer, Galen Brandt & Spangenberg, Wesley G.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Water Injection in Subsonic Diffuser of a Conical Inlet Operation at Free-Stream Mach Number of 2.5

Description: A spike-type nose inlet with sharp-lip cowl was investigated at a free-stream Mach number of 2.5 with water injection in its 16-inch diameter, 11-foot-long subsonic diffuser section. Inlet total temperature of exit with liquid-air ratios of about 0.04 with no apparent change in the critical pressure recovery. The observed temperature drops were less than the theoretically predicted values, and the amount of water evaporated was 35 to 50 percent less than that theoretically possible.
Date: January 15, 1957
Creator: Beke, Andrew
Partner: UNT Libraries Government Documents Department

Investigation of Flow Fluctuations at the Exit of a Radial-Flow Centrifugal Impeller

Description: Memorandum presenting surveys made at the exit of a radial-flow centrifugal impeller to obtain instantaneous values of velocity from blade to blade and at various positions between the front and rear diffuser walls. Surveys were also made at several radial stations midway between the walls of the diffuser to observe the radial change in the flow pattern through the vaneless diffuser. Results regarding typical trace, hub-shroud surveys, and radial surveys are provided.
Date: October 13, 1952
Creator: Hamrick, Joseph T. & Mizisin, John
Partner: UNT Libraries Government Documents Department

Investigation of Perforated Convergent-Divergent Diffusers With Initial Boundary Layer

Description: An experimental investigation was made at Mach number 1.90 of the performance of a series of perforated convergent-divergent supersonic diffusers operating with initial boundary layer, which was induced and controlled by lengths of cylindrical inlets affixed to the diffusers. Supercritical mass-flow and peak total-pressure recoveries were decreased slightly by use of the longest inlets (4 inlet diameters in length). Combinations of cylindrical inlets, perforated diffusers, and subsonic diffuser were evaluated as simulated wind tunnels having second throats. Comparisons with noncontracted configurations of similar scale indicated conservatively computed power reductions of 25 percent.
Date: August 15, 1950
Creator: Weinstein, Maynard I.
Partner: UNT Libraries Government Documents Department

Effect of Screens in Wide-Angle Diffusers

Description: "An experimental investigation at low airspeeds was made of the filling effect observed when a screen or similar resistance is placed across a diffuser. The filling effect is found to be real in that screens can prevent separation or restore separated flow in diffusers even of extreme divergence and to depend principally on screen location and pressure-drop coefficient of the screen. Results are given for three different diffusers of circular cross section with a variety of screen arrangements. Effects of single screens and multiple screens are shown" (p. 1).
Date: June 26, 1947
Creator: Schubauer, G. B. & Spangenberg, W. G.
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of Use of Conical Flow Separation for Efficient Supersonic Diffusion

Description: Use of flow separation on a rod projecting upstream of a blunt body to decelerate the supersonic stream ahead of an annular nose inlet was investigated at Mach numbers of 1.76, 1.93, and 2.10. Maximum pressure recoveries were obtained with rod tip projections about 1.5 times the radius of the spherical nose and were higher than those obtained with single-shock solid cones. Subcritical operation was similar to that observed with solid-cone inlets, but the effect of angle of attack on maximum pressure recovery was more severe.
Date: December 17, 1951
Creator: Moeckel, W. E. & Evans, P. J., Jr.
Partner: UNT Libraries Government Documents Department

Effect of Surface Roughness Over the Downstream Region of a 23 Degree Conical Diffuser

Description: Note presenting an experimental investigation conducted to determine the effects of varying extents of surface roughness over the downstream region of a 23 degree conical diffuser with an inlet-boundary-layer thickness of the order of 5 percent of the inlet diameter. The air flows used in the investigation cover an inlet Mach number range from about 0.10 to 0.40. The results indicate that the flow in the roughened diffuser was steady and reproducible for all conditions.
Date: January 1954
Creator: Persh, Jerome & Bailey, Bruce M.
Partner: UNT Libraries Government Documents Department

Theory of Plane, Symmetrical Intake Diffusers

Description: "The present report ties in with the investigations on the inlet diffusers by P. Ruden. The theory developed by Ruden had produced results which found excellent confirmation in wind-tunnel tests and in spite of certain still-existing defects, are technically very promising. The reasons for the new theory of the diffuser forms indicated by Ruden are twofold: first, the arguments adduced in Ruden's theory deal only with one specific operating condition, that is, a certain ratio of mean velocity within the diffuser to flying speed, while in the present report any desired velocity ratios are involved; second, a different choice of parameters and the increased possibilities of variation result in diffuser forms which cannot be reconciled at once with Ruden's theory" (p. 1).
Date: April 1950
Creator: Brödel, Walter
Partner: UNT Libraries Government Documents Department

An investigation of diffuser-resistance combinations in duct systems

Description: Report presenting an investigation to determine the properties of diffuser-resistance combinations. The work applies to the design of airplane cooling ducts in which air is expanded in front of resistances, such as radiators, oil coolers, intercoolers, or the cylinders of an air-cooled engine.
Date: February 1942
Creator: McLellan, Charles H. & Nichols, Mark R.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of short two-dimensional subsonic diffusers

Description: Report presenting several short two-dimensional subsonic diffusers over a range of throat Mach numbers from 0.3 to 0.9. The designs incorporated an effective diffusion angle of approximately 30 degrees and an area ratio of 3. At a throat Mach number of 0.7, the resulting profile distortion of the unmodified 30 degree diffuser was diminished from about 11 to approximately 4 percent by using any of the configurations.
Date: May 25, 1956
Creator: Woollett, Richard R.
Partner: UNT Libraries Government Documents Department