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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

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

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

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

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

High Mach number, low-cowl-drag, external-compression inlet with subsonic dump diffuser

Description: Report presenting an investigation of a zero-cowl-drag, all-external-compression inlet with an abrupt area discontinuity or subsonic dump diffuser for high Mach number application. Results regarding the diffuser performance characteristics, effect of spike retraction, a comparison with other inlets, and some theoretical calculations related to the results are provided.
Date: May 12, 1958
Creator: Connors, James F. & Flaherty, Richard J.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of a translating cowl technique for improving take-off performance of a sharp-lip supersonic diffuser

Description: A preliminary investigation was conducted in quiescent air on a translating cowl technique for improving the take-off performance of a sharp-lip supersonic diffuser. The technique consists of cutting the cowling in a plane normal to its axis and then translating the forepart of the cowling in the forward direction. The leading edge of the fixed portion of the cowling is rounded. Appreciable improved inlet performance was obtained with a cowling translation corresponding to a gap of only 1/4 inlet radius.
Date: November 28, 1951
Creator: Cortright, Edgar M., Jr.
Partner: UNT Libraries Government Documents Department

Full-scale, free-jet investigation of methods of improving outlet flow distribution in a side-inlet supersonic diffuser

Description: Report presenting a full-scale, free-jet investigation to determine the performance of a side-inlet supersonic diffuser designed for a flight Mach number of 2.75. Several internal modifications made to improve diffuser-outlet flow uniformity were also evaluated. Results regarding the general characteristics of the diffuser and effect of diffuser modifications on flow distribution are provided.
Date: March 28, 1955
Creator: Farley, John M. & Seashore, Ferris L.
Partner: UNT Libraries Government Documents Department

The use of perforated inlets for efficient supersonic diffusion

Description: Report presenting the use of wall perforations on supersonic diffusers to avoid the internal contraction-ratio limitation. Experimental results on a preliminary model of a perforated diffuser at Mach number 1.85 are provided. A theoretical discussion of the flow coefficients and the size and spacing of the perforations are included.
Date: September 1956
Creator: Evvard, John C. & Blakey, John W.
Partner: UNT Libraries Government Documents Department

The use of perforated inlets for efficient supersonic diffusion

Description: Report presenting the use of wall perforations on supersonic diffusers to avoid the internal contraction-ratio limitation. Experimental results on a preliminary model of a perforated diffuser at Mach number 1.85 are provided. A theoretical discussion of the flow coefficients and the size and spacing of the perforations are included.
Date: June 25, 1947
Creator: Evvard, John C. & Blakey, John W.
Partner: UNT Libraries Government Documents Department

Design and performance of family of diffusing scrolls with mixed-flow impeller and vaneless diffuser

Description: A family of diffusing scrolls was designed for use with a mixed-flow impeller and a small-diameter vaneless diffuser. The design theory, intended to maintain a uniform pressure around the scroll inlet, permits determination of the position of scroll cross sections of preassigned area by considering the radial variation in fluid density and the effects of friction along the scroll. Inasmuch as the design method leaves the cross-sectional shape undetermined, the effect of certain variations in scroll shape was investigated by studying scrolls having angles of divergence (of the scroll walls downstream of the entrance section) of 24 degrees, 40 degrees, and 80 degrees. A second 80 degree scroll was of asymmetrical construction and a third was plaster-cast instead of sand-cast. Each scroll was tested as a compressor component at actual impeller tip speeds of 700 to 1300 feet per second from full throttle to surge.
Date: October 1947
Creator: Brown, W. Byron & Bradshaw, Guy R.
Partner: UNT Libraries Government Documents Department

Comparative performance of two vaneless diffusers designed with different rates of passage curvature for mixed-flow impellers

Description: Report presenting an investigation of the effect of diffuser performance of the passage curvature of two vaneless diffusers designed with a 6 degree equivalent-cone divergence angle along a logarithmic-spiral path in combination with two mixed-flow impellers. The peak of overall adiabatic efficiency is compared with the corresponding diffuser efficiency. Results regarding the variation of diffuser efficiency with load-coefficient parameter and peak overall adiabatic efficiencies and corresponding diffuser efficiencies of the two compressors are provided.
Date: November 1947
Creator: Barina, Frank J.
Partner: UNT Libraries Government Documents Department

Some observations of flow at the throat of a two-dimensional diffuser at a Mach number of 3.85

Description: Report presenting an experimental investigation at a Mach number of 3.85 in the supersonic wind tunnel to study the flow patterns at the throat of a two-dimensional single-shock diffuser and to evaluate qualitatively several schemes for improving the turning conditions. Schileren observations were made for supercritical inlet operation and conditions of maximum total-pressure recovery.
Date: November 13, 1952
Creator: Connors, James F. & Woollett, Richard R.
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

Effect of screens in reducing distortion and diffusion length for a 'dump' diffuser at a Mach number of 3.85

Description: Report presenting an investigation of the effect of screens in a dump-type diffuser in the 2- by 2-foot supersonic wind tunnel at Mach number 3.85. Results of a slanted half screen of 0.41 solidity, positioned 0.263 inlet diameter from the cowl lip, are presented on a range basis, as this configuration allows for shortening of the subsonic diffuser.
Date: July 15, 1958
Creator: Wasserbauer, Joseph F.
Partner: UNT Libraries Government Documents Department

Investigation of High-Subsonic Performance Characteristics of a 12 Degree 21-Inch Conical Diffuser, Including the Effects of Change in Inlet-Boundary-Layer Thickness

Description: "Investigations were conducted of a 12 degree 21-inch conical diffuser of 2:1 area ratio to determine the interrelation of boundary layer growth and performance characteristics. Surveys were made of inlet and exit from, longitudinal static pressures were recorded, and velocity profiles were obtained through an inlet Reynolds number range, determined from mass flows and based on inlet diameter of 1.45 x 10(exp 6) to 7.45 x 10(exp 6) and a Mach number range of 0.11 to approximately choking. These investigations were made to two thicknesses of inlet boundary layer" (p. 1).
Date: March 24, 1950
Creator: Copp, Martin R. & Klevatt, Paul L.
Partner: UNT Libraries Government Documents Department

Characteristics of perforated diffusers at free-stream Mach number 1.90

Description: "An investigation was conducted at Mach number 1.90 to determine pressure recovery and mass-flow characteristics of series of perforated convergent-divergent supersonic diffusers. Pressure recoveries as high as 96 percent were obtained, but at reduced mass flows through the diffuser. Theoretical considerations of effect of perforation distribution on shock stability in converging section of diffuser are presented and correlated with experimental data. A method of estimating relative importance of pressure recovery and mass flow on internal thrust coefficient basis is given and a comparison of various diffusers investigated is made" (p. 1).
Date: May 8, 1950
Creator: Hunczak, Henry R. & Kremzier, Emil J.
Partner: UNT Libraries Government Documents Department

One-dimensional compressible flow in vaneless diffusers of radial- and mixed-flow centrifugal compressors, including effects of friction, heat transfer and area change

Description: Report presenting an analysis method and a design method for one-dimensional, compressible flow with friction, heat transfer, and area change in vaneless diffusers with arbitrary profiles in the axial-radial plane. The effects of mixing losses due to nonuniform flow conditions at the impeller discharge are not considered.
Date: January 1952
Creator: Stanitz, John D.
Partner: UNT Libraries Government Documents Department

Effects of shock-boundary-layer interaction on the performance of a long and a short subsonic annular diffuser

Description: Report presenting an investigation to determine the effects on performance of positioning normal shocks in or upstream of both a long and a short subsonic annular diffuser. Results regarding the entrance flow conditions, performance for subsonic-entrance flows, and performance with choked- and supersonic-entrance flows are provided.
Date: April 15, 1958
Creator: Wood, Charles C. & Henry, John R.
Partner: UNT Libraries Government Documents Department

Summary of subsonic-diffuser data

Description: Report presenting a review of subsonic-diffuser data, which was reduced to certain appropriate performance coefficients and presented as functions of the significant geometric and flow variables. The report is divided into the following sections: performance at low speeds, the effect of increasing the inlet speed up to choking Mach numbers, illustrations of the effectiveness of boundary-layer controls, and illustrations of the effects of distorted inlet velocity distributions at subsonic speeds.
Date: October 12, 1956
Creator: Henry, John R.; Wood, Charles C. & Wilbur, Stafford W.
Partner: UNT Libraries Government Documents Department