Showing papers on "Diffuser (thermodynamics) published in 1973"

Turbine coolant flow system

Abstract: In a turbine engine compressed air is delivered through a diffuser to a burner section and then through a turbine section. A portion of the compressed air from said diffuser is removed by an annular center body manifold and directed by hollow struts inwardly to an annular passageway where the compressed air flow is taken to the forward part of the turbine section. The flow from the annular passageway is then directed into a passageway having directing vanes for imparting a desired velocity and direction to the existing flow so as to be compatible with the rotating turbine disk onto which it flows. This air is then directed to cool blades on that disk and also passed through that disk to be directed to turbine blades on the next disk. The invention herein described was made in the course of or under a contract with the Department of the Air Force.

Turbulence in a conical diffuser with fully developed flow at entry

Abstract: An experimental study of the structure of turbulence in a conical diffuser having a total divergence angle of 8° and an area ratio of 4: 1 with fully developed flow at entry is described. Theresearch has been done for pipe entry Reynolds numbers of 152 000 and 293000 of profiles of the mean pressure, mean velocity, turbulence intensities, correlation coefficients and the one-dimensional energy spectra, but owing to similar behaviour for these two Reynolds numbers, data are presented for a Reynolds number of 293 000.The results show that the rate of turbulent energy production approximately reaches a maximum value at the edge of the wall layer extending to the point of maximum u1-fluctuation. It is found that, within the layer, varies linearly with the distance from the wall and the linear range grows with distance in the downstream direction.The turbulent kinetic energy balance indicates that the magnitude of the energy convective diffusion due to kinetic and pressure effects is comparable with that of the energy production.

Humidifier and heater for delivered gas

Abstract: A humidifier for delivered gases which has a water container with a cover provided with a gas inlet and a gas outlet, both inlet and outlet being further provided with removable tubing adaptors. A gas conveying assembly is within the water container, and includes a delivery tube which adjoins the inlet and which also extends below a diffuser plate to a rebound chamber between the bottom of the water container and the diffuser plate. A plurality of apertures in the diffuser plate have an aggregate area which is substantially equal to the area of the discharge, said apertures being spaced from said discharge in a pattern of aligned linear radial rows and concentric rows. The cover of the humidifier is also provided with a pressure relief valve which opens when predetermined pressure levels are exceeded within the container, and which can be closed in the event high pressure humidification is desired.

Diffuser for a centrifugal compressor

Abstract: A diffuser for a centrifugal compressor has a body defining diffusing passages extending tangentially and radially from an annular space around the circumference of the compressor impeller. These passages diverge in the direction of flow and trend smoothly in cross-section from rectangular at the inlet to circular at the outlet in the preferred case. The cross-section of the passage follows the relation X/A S + Y/b s 1, WHERE X AND Y ARE COORDINATES, A AND B ARE WIDTH AND DEPTH PARAMETERS, AND S IS A SHAPE FACTOR WHICH VARIES PROGRESSIVELY ALONG THE DIFFUSING PASSAGE FROM NEAR INFINITY AT THE INLET TO PREFERABLY 2 AT THE OUTLET.

Vortex diffuser fluid bearing device

Abstract: A fluid bearing load supporting system having unidirectional and omnidirectional capabilities which embodies means for forming one or a plurality of fluid vortices for separating a body from a supporting surface by an intervening cushion of fluid, providing therewith an extremely low coefficient of friction that facilitates a conveyance of the body for the purposes of transportation, processing, treatment and the like.

Pressure recovery performance of conical diffusers at high subsonic Mach numbers

Abstract: The pressure recovery performance of conical diffusers has been measured for a wide range of geometries and inlet flow conditions. The approximate level and location (in terms of diffuser geometry of optimum performance were determined. Throat Mach numbers from low subsonic (m sub t equals 0.2) through choking (m sub t equals 1.0) were investigated in combination with throat blockage from 0.03 to 0.12. For fixed Mach number, performance was measured over a fourfold range of inlet Reynolds number. Maps of pressure recovery are presented as a function of diffuser geometry for fixed sets of inlet conditions. The influence of inlet blockage, throat Mach number, and inlet Reynolds number is discussed.

Compressor inlet control ring

Abstract: A centrifugal compressor includes a stationary outer shroud and a centrifugal rotor with an inner hub wall located radially inwardly of the stationary shroud to define an axial inlet and a radial outlet. A plurality of centrifugal blades located on the hub wall define a plurality of circumferentially spaced flow passages for compression of working fluid drawn from the axial inlet for discharge through the radial outlet. Means are included at the inlet end of the stationary shroud to direct additional flow into the flow passages between each of the centrifugal blades on the rotor to relieve partial vacuum conditions existing between the stationary shroud wall and the rotor tips at the inlet end thereof to improve the rotor exit pressure and velocity gradient thereby to increase efficiency of a following diffuser located downstream of the radial outlet of the compressor.

Centrifugal pump diffuser

Abstract: A rotary pump having a plurality of impeller blades and a plurality of circumferentially spaced vanes located about the periphery of said blades. The blades and vanes cause the fluid being acted upon by the pump to be delivered in pressure pulses of relatively high frequency and low magnitude. The spacing between adjacent vanes is nonuniform to prohibit uniform pressure patterns in the process fluid.

Theoretical and experimental internal flow characteristics of a 13.97-centimeter-diameter inlet at STOL takeoff and approach conditions

Abstract: The theoretical and experimental internal flow characteristics of a 13.97-cm-diam inlet with centerbody retracted and extended are presented at STOL takeoff and approach operating conditions. The theoretical results were obtained from incompressible potential flow corrected for compressibility and boundary layer. Comparisons between theoretical internal surface static-pressure distributions and experimental data are presented for free-stream velocities of 0, 24, 32, and 45 m/sec for a range of inlet incidence angles from 0 to 50 deg. Surface static-pressure distributions are illustrated at circumferential locations of 0, 60, 120, and 180 deg. Surface Mach number distributions from the stagnation point to the diffuser exit are presented along with turbulent boundary-layer shape factors. In general, good agreement was found between the theoretical and experimental surface static pressure distributions.

Ultrasonic transducer with coupling means

Abstract: An apparatus for providing a liquid coupling to a body under test has in sequence within a housing an inlet for receiving coupling liquid from a suitable pressurised source, a diffuser for equalising liquid pressure across the housing section, an arrangement for straightening the flow of liquid within the housing so as to tend to produce laminar flow from an outlet of the housing which is provided with a restriction ensuring positive liquid pressure in the housing. In the case where the apparatus is to be used for coupling an ultrasonic transducer to the body under test by way of the liquid, the transducer is disposed in the housing, preferably downstream of the diffuser so that its active surface comes into contact with the liquid flowing through the housing for incidence upon the body.

Advantages of the diffuser-augmented wind turbine

Abstract: Performance optimization for a wind turbine is realized by using a shrouded diffuser to produce up to twice the power of unshrouded turbines of the same diameter. The diffuser converts the kinetic energy of the flow downstream of the rotor into a pressure rise and thus makes it possible for the rotor to capture airflow from a free stream tube area that is greater than that from the rotor itself. The flow velocity through the shrouded rotor is 20 to 60 percent greater than the free wind velocity as opposed to 67 percent less for the unshrouded case. The diffuser also makes it possible to accommodate very high wind speeds without the need of variable pitch in the rotor blades.

Effects of Curvature on Two-Dimensional Diffuser Flow

Abstract: The effects of curvature on diffusers have been studied experimentally and analytically. Measurements of wall pressures and boundary layer velocities have been made in three test diffusers of zero or mild curvature, in which the flow is not separated. The straight diffuser results were in very good accord with the results of flow calculations based on the Stanitz and Moses methods for treating the potential core and boundary layer regions, respectively. The curved diffuser flow measurements indicated pronounced effects of curvature on pressure and velocity distributions. Effects of curvature on boundary layers are ascribed to shear stress modification, and shown to be roughly predictable using a linear mixing length – Richardson number correlation.

Two-piece channel diffuser

Abstract: A channel diffuser for a centrifugal compressor in which the diffuser is formed from two annular elements, sandwiched together. One element is a flangelike portion of the outer housing for an engine and has a smooth radially extending face. The second element has a series of tangentially directed channels open toward the radial face on the first element to form diffuser passages. The channels in the second element diverge both in width and in height so that all the divergence in the passages is provided by the channels.

Base Flow Characteristics of a Linear Aerospike Nozzle Segment

Abstract: The separated base flow region within a linear aerospike nozzle segment is investigated experimentally in an ejector-diffuser system. The nozzle-diffuser system and base pressure characteristics are described over the pressure ratio range from the 'open wake' to the 'closed wake' operation. Schlieren photographs and static pressure distributions along the test section centerline and top contour describe the transition from 'open wake' to 'closed wake' flow fields. Base pressure and static pressure distributions are utilized to present the effects of a ramp diffuser. The effects of base bleed on the base pressure ratio and structure of the nozzle flow field are also presented.

Diffuser with boundary layer removal

Abstract: A diffuser for a radial flow compressor has a body defining radially and tangentially extending diffusing passages from near the compressor rotor into a plenum surrounding the diffuser body. A curved diverging outlet tube is mounted in a socket at the outer end of each diffusing passage. A slot extending around the diffusing passage at the inner end of each outlet tube receives boundary layer air from the passage and directs it into a recess on the exterior of the outlet tube. All these recesses are connected to a common manifold from which the boundary layer air is directed to any suitable receiver.

Design and experimental performance of short curved wall diffusers with axial symmetry utilizing slot suction

Abstract: The feasibility of designing short curved wall axially symmetrical subsonic diffusers utilizing suction through slots in the diffuser walls to prevent flow separation was investigated. A potential flow analysis was made, and a digital computer program was written for determining the diffuser wall contour for prescribed boundary conditions. The flow field included branch flow so that the suction slot geometry could be a part of the diffuser design. One bell shaped diffuser and three annular diffusers with area ratios of either 2.5:1 or 3:1 were designed, fabricated, and tested. Minimum suction requirements of metastable operation ranged from 6.3 percent to 12 percent when operating with inlet air velocities in the 1000 to 250 ft/sec (30 to 76 m/sec) range. For stable operation suction rates from 10 percent to 22 percent were required. In all cases the diffuser effectiveness was above 95 percent based on the conventional definition, and from 81 percent to 94 percent when the suction loss was accounted for. The exit velocity profiles were virtually flat with no more than + or - 9% variation over 95 percent of the exit area when operated with sufficient suction to prevent flow separation.

Investigation of Two-Dimensional Cavity Diffusers,

Abstract: : An investigation was conducted to determine the flow regimes and performance of 2-D cavity diffusers. Water table flow visualization tests were conducted over a wide range of diffuser divergence angles and diffuser length to throat-width ratios. Air flow tests were conducted from Mach numbers of .06 to .6 on a 1/3 scale model to obtain diffuser performance. Results indicate that a single cavity can delay separation in 2-D straight wall diffusers, but that static pressure recovery is reduced. In both tests self-induced resonance was encountered which can be reasonably predicted by a vortex wave interaction model. (Author)

One piece radial vane diffuser and method of manufacturing the same

Abstract: A one piece radial vane diffuser constitutes an annular array of curved, radially directed vanes, surrounding the combustion area of a fuel oil burner, downstream of the nozzle, and at the downstream end of a cylinder defining a primary air flow path concentric with the nozzle. A circular sheet metal sheet is first drawn into a cone, the vanes are lanced from the cone to form a circumferential array of integral, radially directed, side by side, generally rectangular vanes linked to an annular rim at their radial outermost ends by an integral hinge. The cone is then flattened, at least in the area of the vanes, to cause the vanes to move into edge overlapping position and preferably the vanes are bent or twisted about a radial axis passing through the hinge to provide air passages between vanes of predetermined size. The vanes may be curved relative to their radial axes to effect swirling of the primary air flow.

Control of exit velocity profile of an asymmetric annular diffuser using wall suction

Abstract: An asymmetric annular diffuser equipped with wall bleed (suction) capability was tested for controllability of exit velocity profile. The diffuser area ratio was 3.2, and the length to inlet height ratio was 1.6. Results show that the diffuser radial exit velocity profile could be controlled from a hub peaked to a tip peaked form by selective use of bleed on the outer wall or on both diffuser walls. Based on these results, application of the diffuser bleed technique to gas turbine combustors may be possible. Diffuser bleed could be used to tailor the airflow distribution for optimizing combustor performance at a variety of operating conditions.

Streamline curvature design procedure for subsonic and transonic ducts

Abstract: A procedure for designing ducts for subsonic and transonic speeds is described. Examples discussed are a wind-tunnel contraction cone, a supersonic nozzle, and a diffuser. A listing of the computer program is included. The streamline curvature equations represent a form of the exact, compressible, inviscid flow equations. The method is applicable from low subsonic to supersonic speeds.

By-pass flow diffuser

Abstract: A hydraulic brake booster is disclosed which includes a housing defining a pressure chamber therewithin in which a boost piston reciprocates and which is also provided with an inlet port connected to the fluid pressure source, an outlet port, and a return or exhuast port communicated to a fluid reservoir. A spool valve is slidably mounted in the housing and is shiftable from a first or brake released position in which the pressure chamber is vented to the reservoir and in which substantially all of the fluid flowing to the inlet is communicated directly to the outlet, to a second position in which fluid flow between the inlet and the outlet is severely restricted and the high pressure fluid at the inlet is communicated into the booster pressure chamber where it acts upon the boost piston to effect a brake application. A by-pass passage is provided between the inlet and outlet port to insure a minimum level of fluid communication between the inlet and outlet even when the spool valve is disposed in the second position. The by-pass passage includes a first flow-restricting orifice which communicates the inlet with a cavity, and a second flow-restricting orifice or diffuser which communicates the cavity to the outlet ports. The two orifices are so designed that the pressure drop across the first orifice is much greater than the pressure drop across the second orifice or diffuser, thereby providing a substantially noiseless valve which may be easily manufactured.

Injector for furnishing liquid at a low pressure to a vessel at a higher pressure

Abstract: An injector for furnishing liquid at a low pressure to a vessel at a higher pressure comprising: an enclosed chamber having, at the bottom end, a centrally located downwardly converging combining tube, and in the middle, an annular trough whose circumferential lip defines a central opening connecting the upper end of the chamber to the lower end, means for conducting low pressure liquid into the trough from which it overflows, a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central opening and terminating in the lower chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching the liquid overflowing from the trough and causing it to pour over the flange in a continuous, circumferential concavely shaped curtain of liquid so that high pressure vapor furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream, and a diverging diffuser tube connected to the outlet of the combining tube for slowing the stream and converting its velocity head to a pressure head.

Oscillatory Flow Phenomena in Diffusers at Low Reynolds Numbers

Abstract: In studies of a diffuser operating with inlet flow oscillations, it has been found that large amplification of the inlet velocity oscillations occurs within the diffuser when the throat Reynolds number lies in the range 103 to 104 . This phenomenon is caused by travelling waves in the wall boundary layer which are initiated in the laminar portion of the boundary layer and propagate into the turbulent boundary layer, causing large variations in the displacement thickness.

Closed cycle gas dynamic laser

Abstract: The device includes a closed cycle gas dynamic laser wherein the lasing fluid is recirculated in a closed loop. The closed loop includes a nozzle array, a lasing cavity and a diffuser. The exit of the diffuser is connected to the inlet to the nozzle array with a fuel heat exchanger located in the lasing flow and a pumping means located between the heat exchanger and the nozzle array. To provide for cooling of the pumping means and to improve diffuser performance, gas bled from the diffuser is cooled by two heat exchangers and pumped into cooling passages in the pumping means. The heat exchangers for cooling the flow to the pumping means are located in series and carry fuel from a supply to an injector in said combustor and the heat exchanger in the lasing flow cools the fluid and carries the fuel from a supply to an injector in said combustor.

Nozzle area measurement

Abstract: The apparatus determines the area of variable openings in a jet engine using radar techniques, and is particularly useful in determining the nozzle exit area. A radar antenna is mounted within the diffuser and is directed towards the nozzle so that a radar signal will impinge on the vanes defining the nozzle opening. Radar apparatus is connected to the antenna to provide the signal to be radiated and to receive the reflected signal. The reflected signal is related to the area of the opening and may be used to drive a display device to show the opening area. The signal representing nozzle area A8 may be used with a signal representing static pressure at the nozzle entrance PSN and a signal representing ambient static pressure PSO to compute gross thrust.

Performance of a low-pressure-ratio centrifugal compressor with four diffuser designs

Abstract: A low-pressure-ratio centrifugal compressor was tested with four different diffuser configurations. One diffuser had airfoil vanes. Two were pipe diffusers. One pipe diffuser had 7.5 deg cone diffusing passages. The other had trumpet-shaped passages designed for linear static-pressure rise from throat to exit. The fourth configuration had flat vanes with elliptical leading edges similar to those of pipe diffusers. The side walls were contoured to produce a linear pressure rise. Peak compressor efficiencies were 0.82 with the airfoil vane and conical pipe diffusers, 0.80 with the trumpet, and 0.74 with the flat-vane design. Surge margin and useful range were greater for the airfoil-vane diffuser than for the other three.

Methods and apparatus for determining the thrust of a jet engine

Abstract: Apparatus is known for determining gross thrust in jet engines by measuring various internal pressures, including measurement of total pressure at the nozzle entrance by means of an immersed probe. The immersed probe has a very short life when an afterburner is used in the engine. The apparatus for the invention is able to determine total pressure at the nozzle entrance, without an immersed probe, from the total pressure in the diffuser and the static pressure at the nozzle entrance. Another embodiment makes use of an additional static pressure in the flame-holder region. Also, the invention is for determining the gross thrust of an engine and it distinguishes between an engine with a nozzle operating in a choked condition and an unchoked condition.

Investigations of a Variable Geometry Compressor for a Diesel Engine Turbocharger

Abstract: : An analytical and experimental investigation was conducted to determine the most practical method of surge control for advanced diesel turbocharger compressors Results of the analysis indicated that a vaned diffuser actuation system represented a good method of achieving effective regulation over a broad range of flow rates Bench testing of the fabricated hardware indicated that the variable diffuser method has the ability to regulate flow and control surge without excessive reduction of efficiency or pressure ratio