Showing papers on "Diffuser (thermodynamics) published in 1974"

Gas Compression With the Liquid Jet Pump

Abstract: The isothermal compression of a gas by a liquid jet in a mixing throat followed by secondary compression in a diffuser is described by a one dimensional model including frictional losses. Good theory-experiment agreement is shown; pump efficiencies can exceed 40 percent. Mixing throat and diffuser energy analyses are presented. The isothermal compression mechanism in the throat is related to momentum transfer while the diffuser process consists of a pistonlike compression of entrained gas bubbles by the continuous liquid medium. The efficiency of a liquid-jet gas pump depends primarily on the mixing loss. The mixing loss function, the throat compression ratio and the Mach number are developed as functions of the throat inlet velocity ratio v and the jet pump number n. A zero mixing loss criterion defines the theoretically possible region of pump operation. Design applications are discussed.

Self-aligning vanes for a turbomachine

Abstract: The outlet of a centrifugal compressor is provided with an annular row of movable diffuser vanes which align with the fluid flow direction to prevent a surge condition. Each movable diffuser vane has a pivot axis forward of the vane's center of pressure to cause the fluid from the impeller to move the vane such that the flow meets the diffuser vane leading edge with a near-zero incident angle. The vanes are floating or freely movable on the pivot axis except for spring bias which prevents flutter. In some embodiments, the movable vanes are upstream of primary fixed diffuser vanes, of the vane-island or of the airfoil vane type, and are movable between a closed position abutting the primary vanes to variable open positions which create auxiliary diffuser channels.

Combustion inlet diffuser employing boundary layer flow straightening vanes

Abstract: The boundary layer along a combustor inlet diffuser is stablilized by removing the swirl from the normally swirling air flow along the walls, thereby increasing the axial component of the flow velocity along the diffuser walls. The invention is applied to an annular burner of swirl flow configuration, and permits the utilization of a very wide and short cone angle diffuser to reduce burner length.

Apparatus for filtering particulate matter from gas and having reverse flow cleaning means

Abstract: Apparatus for filtering dust particles from air comprises a plurality of flexible tubular-shaped gas permeable filter elements through which dust-laden air is constrained to pass in flowing through the apparatus. Each filter element has a cleanair outlet opening from which filtered air is withdrawn and a frustroconical diffuser disposed externally thereof in coaxial alignment with and axially spaced from the outlet opening. Means is provided to direct high velocity streams of air to and along the outer surface of the diffuser and in the direction of the outlet opening whereby the streams are evenly distributed over the surface of the diffuser and enter the filter element and flow therethrough in a controlled manner and in a direction counter to the direction of filtered air flow therefrom.

High efficiency cyclone separator

Abstract: A cyclone separator having a central fluid conduit. An interceptor ring is externally attached to the end of the fluid conduit and has a surface which intercepts fluid flowing longitudinally along the outer surface of the fluid conduit and directs the fluid outwardly toward the interior wall of the container. Circumferential and longitudinal slots are located in the container in proximity to the interceptor ring to enhance the outward direction flow of fluid from the ring. A diffuser collar having a central opening therein is connected to the interceptor ring in a manner leaving an annular space or circumferential slots between the ring and the collar through which space unwanted materials. In an alternate version the diffuser collar is larger in diameter than the fluid conduit and the conduit extends into the diffuser collar forming a space therebetween by which an outer layer of fluid is skimmed from the spiraling column of fluid entering the fluid conduit to further cleanse the fluid of unwanted substances. Curved vanes connect the diffuser collar to the fluid conduit. The open end of the diffuser collar may also have an interceptor ring and the container may have a circumferential slot in proximity to the interceptor ring to enhance the direction of fluids outwardly from the interceptor ring. In still another version, a second container may be symmetrically located interior to the first container to surround the one end of the fluid conduit. One end of the second container is connected to the fluid deflector apparatus and the other end is open.

Supersonic shock wave compressor diffuser with circular arc channels

Abstract: A supersonic shock wave compressor diffuser forms a concentric annulus about a radial compressor having a central axis. Circular channels diverge with an increasing divergence angle as they extend along an arcuate longitudinal center line from an inner circumference very near the periphery of the compressor to the outer circumference of the diffuser. Shock waves may occur within the channels near the inner circumference of the diffuser or may occur within a vaneless diffusion space adjacent the periphery of the compressor and provide efficient energy conversion and reduce the velocity substantially below MACH 1 to further improve the efficiency of the subsonic diffusion downstream therefrom. A logarithmic spiral is approximated by a circular arc subtended by the channel longitudinal axes to permit recovery of angular momentum while the circular cross section of the channels permits recovery of swirl velocity energy. The required diameter of the outer circumference of the diffuser is reduced by using the shock waves to greatly reduce gas velocity within a short distance, by the curvature of the channels and by the angle of incidence of the longitudinal channel axes.

Inflator for vehicle occupant restraint system

Abstract: An inflator is provided for inflating the expandable confinement of a vehicle occupant restraint system, to restrain an occupant in response to a collision signal. The inflator contains a source of inflation fluid, such as a propellant which is ignited upon the receipt of the collision signal. The inflator has fluid-directing means including passage means for the flow of the inflating fluid therethrough. A deformable diffuser is provided having a first position in sealing engagement with the outer surface of the inflator to seal the passage means, and a second position, subsequent to the ignition of the propellant, in which a portion of the diffuser is deformed out of sealing engagement with the inflator to permit passage of the inflating fluid. The fluid is directed by the diffuser radially away from the housing to inflate the confinement.

Centrifugal compressor boundary layer control

Abstract: A centrifugal compressor is shown with an inlet directing a fluid thereto and a diffuser into which the compressor directs its output. A group or array of circumferential grooves are located in the surface of a stationary shroud which covers the blades of the compressor.

Multiple orifice assembly

Abstract: A multiple orifice assembly for increasing the flow resistance in a conduit for conducting fluid flow. The multiple orifice assembly comprises a plurality of orifices spacedly supported in the conduit and a diffuser which is supported intermediate adjacent orifices. The diffuser is spaced from the upstream orifice a distance less than that distance required for fluid issuing from the upstream orifice to fully expand back to the constraints of the conduit.

Radial flow compressors

Abstract: A radial flow compressor is described in which the diffuser entrance is uniquely contoured to minimize losses attributable to the differences in absolute flow angle of the high velocity air discharged from the compressor impeller, such differences existing across the width of the impeller discharge flow path. The diffuser comprises a plurality of vanes which split the circumferential impeller discharge into discrete, tangential, diffusion channels. Each vane is wedge shaped and has suction and pressure surfaces on opposite sides of the leading edge thereof. The leading edge is angled, or swept, relative to the direction of air flow. The suction surface is angled relative to the impeller axis so that, marginally of the leading edge, it is more tangential at the shroud side of the flow path then at the hub side thereof and an essentially uniform impingement angle of approximately 0* is obtained along the width of the suction surface.

Device to reduce flow induced pressure oscillations in open cavities

Abstract: A combined air flow deflector and diffuser assembly including a main flow deflector vane, a deflector base plate mountable adjacent the trailing edge of an open bomb bay or other cavity of a bomber aircraft, aerospace or other vehicle, and a plurality of support pylons interconnected between and supporting the deflector vane in space relation to the base plate immediately behind the bomb bay or other cavity-trailing edge in the path of, and diverting the airstream away from the vehicle body to thereby partially stabilize the turbulent flow at the shield area or airstream flow adjacent the cavity entrance and, simultaneously therewith, induce a substantial decrease of the excessive pressure oscillations that would otherwise occur within the cavity from the air stream flow passing the open cavity. Additional significant reduction primarily in the cavity pressure oscillations results from the formation of a series of divergent, air flow diffusing slots respectively between the base plate and flow deflector vane, and the support pylons and through which a portion of the air stream flows.

Air intake with deflecting device against foreign objects impinging in the initial direction of air flow at engine nacelles

Abstract: An improvement in an air intake for an aircraft engine, particularly a prop-jet engine, which intake is ring-shaped at the forward part thereof and has a central, non-rotatable body mounted in said intake, which together form an intake diffuser, the improvement comprising a displaceable inlet lip on said intake, said lip being displaceable to sealing contact against said central body and against the direction of air onflow, and said lip in said sealing contact position forming a ring-shaped inlet gap behind said lip.

Low pressure-pulse kinetic pump

Abstract: A centrifugal pump has a recessed impeller and a plurality of diffuser vanes fixed outwardly of the pumping chamber to convert fluid velocities to fluid pressures for output with minimum pressure pulse levels. Multiple axial rows of diffuser vanes may be used about the pumping chamber to further reduce pulse levels and noise in the pump output.

Centrifugal compressor with rotating vaneless diffuser powered by leakage flow

Abstract: The high velocity leakage flow escaping tangentially through the annular clearance space between the impeller and rotating vaneless diffuser in a centrifugal compressor is employed to drive a turbine device attached to the diffuser back wall member, thereby self-powering the rotating diffuser and reducing the leakage flow. Either a turbine blade row sector with a partial arc of admission or a full admission turbine blade row can be used.

Calculated Design Data for the Multiple-Disk Pump Using Incompressible Fluid

Abstract: Earlier analyses of the laminar radically outward flow of Newtonian incompressible fluid between parallel corotating disks have been used to calculate the performance of multiple-disk pumps using such flow passages as the rotor. Such pumps are characterized by certain dimensionless parameters and a large number of computerized calculations have enabled preparation of pump performance maps for pumps idealized as having no losses external to the rotor; these maps show the quantitative dependence of pump efficiency, pressure change and required power on the pump geometry, speed, and on fluid properties. Conventional loss information for the pump entrance and diffuser flows, and conventional bearing, seal, and “disk friction” loss information, must be applied in the design process to provide prediction of actual pump performance and comparison with conventional pumps. The design information is also applicable to low-pressure gas blowers.

Hydrodynamic multi-stage pump

Abstract: A hydrodynamic pump comprising a casing in which a shaft having a plurality of spaced impellers is mounted. The casing is formed with diffuser channels interposed between successive impellers. Each diffuser channel comprises a curved section communicating with the outlet of one impeller and an axially-radial centripetal guide channel having a plurality of vanes located therein. Each of the vanes has a curved pressure face and a curved suction face. The angles of inclination of the curvature of the pressure and suction faces at the inlet end of the vanes are both within the range of 5° to 30°. The angle of inclination of curvature of the outlet with respect to the suction face of the vane is within one 100° to 130° and the angle of inclination of the curvature of the outlet with respect to the discharge pressure face is between 60° to 90°.

High power electrically excited flowing gas laser

Abstract: A high power, cw, high pressure, electrically excited flowing gas laser is disclosed wherein a laser excitation transverse to the direction of gas flow is initiated by a uniform electron beam perpendicular to the gas flow direction. Laser gas supplied to a plenum chamber at a pressure substantially greater than atmospheric pressure is conditioned by a perforated plate nozzle to flow through the laser cavity in a uniform stream at the desired subsonic velocity. A variable angle diffuser is provided downstream from the laser cavity to decelerate and compress the laser gas before exhausting it into the ambient atmosphere such that at the downstream end of the laser excitation region the laser gas is maintained at a pressure slightly lower than atmospheric pressure.

Centrifugal compressor diffuser

Abstract: A diffuser for a centrifugal compressor is a modification of those in which passages of circular cross section merge at the entrances to the passage to define generally elliptical leading edges of the walls which separate the passages The entrance portion of each passage is defined by a basic cross section based upon centerlines which converge in the direction of flow and merge to define a single centerline in the downstream portion of the passages The basic cross section of the passage is defined by an arc approximating a semicircle centered on each branch of the centerline and straight or substantially straight lines connecting the ends of the arcs The upstream centerline in the direction of gas flow of each passage intersects the downstream centerline of the next forward passage at the inner periphery of the diffuser The resulting intersection of the boundaries of the diffusing passages results in a generally elliptical leading edge of the walls which lie between the passages

Performance of an asymmetric short annular diffuser with a nondiverging inner wall using suction

Abstract: The performance of a short highly asymmetric annular diffuser equipped with wall bleed (suction) capability was evaluated at nominal inlet Mach numbers of 0.188, 0.264, and 0.324 with the inlet pressure and temperature at near ambient values. The diffuser had an area ratio of 2.75 and a length- to inlet-height ratio of 1.6. Results show that the radial profiles of diffuser exit velocity could be controlled from a severely hub peaked to a slightly tip biased form by selective use of bleed. At the same time, other performance parameters were also improved. These results indicate the possible application of the diffuser bleed technique to control flow profiles to gas turbine combustors.

In-line filtering device

Abstract: An in-line filter unit is provided for use in a circulating fluid system. Such a unit is made essentially into one piece to insure watertight. A debris reservoir is provided to store the debris removed from the fluid. A diffuser is placed in the line of fluid flow for preventing direct contact by the fluid entering the unit with the filter and for preventing damage to the filter.

Diffuser including a rotary stage

Abstract: A two-stage diffuser is disclosed which is intended to be used with a high pressure ratio centrifugal compressor. The first stage comprises a vaneless diffuser passage having rotating sidewalls that freely turn on bearings mounted coaxially with the compressor rotor. The second stage comprises a stationary vaned-type diffuser. In combination, the two stages provide a compact diffuser having improved efficiency. Gas flow leaving the compressor from the periphery of the impeller at supersonic speed contacts the moving sidewalls of the rotary diffuser stage. By having these walls travel at nearly half the speed of the impeller, relative difference in speed between the gas and the walls is subsonic, hence, no shock wave occurs. Expansion of the gas in the first rotary diffuser stage makes it possible to deliver subsonic gas to the vaned second stage.

Variable throat venturi apparatus for mixing and modulating liquid fuel and intake air to an internal combustion engine

Abstract: Discharge velocity of the air-fuel mixture being supplied through a variable venturi flow passage device to an internal combustion engine at idle to near idle operation of the engine is optimized by controllably varying the area ratio between the throat and exit planes of the device. Opposite jaw faces of the device define the flow passage that is gradually opened and closed in correlation to demand imposed on the engine between idle and full throttle operation. Area ratio control in one form is achieved by apparatus operative to selectively vary the diffuser angle between the opposing jaw faces. Area ratio control in another form is achieved by apparatus operative to effect a localized passage opening at idle of selectively different aspect ratio than the aspect ratio defined over the full longitudinal extent of the jaw faces.

Boundary-layer analysis of subsonic inlet diffuser geometries for engines nacelles

Abstract: Theoretical Mach number distributions and boundary-layer parameters are presented for subsonic nacelle inlet diffuser geometries with length to exit diameter ratios ranging from 0.4 to 1.6 and diffuser exit area to throat area ratios ranging from 1.1 to 2.0. The major portion of the study was done with a cubic diffuser contour with the inflection point at the midpoint of the diffuser, a diffuser throat Mach number of 0.6, and a free-stream Mach number of 0.12. Calculations were performed at both model (diffuser exit diameter, 30.5 cm) and full-scale (diffuser exit diameter, 183 cm) sizes. Separation limits were defined by establishing a separation boundary on plots of diffuser area ratio as a function of diffuser length to diameter ratio. The effects of diffuser contour, inlet lip geometry, and throat Mach number on the boundary-layer characteristics are illustrated. The major results of the study indicate that the separation boundary is shifted to greater area ratios by (1) increasing the diffuser length, (2) increasing the scale of the diffuser and, (3) moving the inflection point of the diffuser contour to or ahead of the midpoint of the diffuser.

Centrifugal pump recirculation diffuser

Abstract: A recirculation diffuser for centrifugal pumps that produces a continuousrising head capacity curve and at the same time reduces levels of impeller vane-frequency sound and other high level acoustic flow tones. The conventional vane diffuser in the pump casing at the periphery of the rotary impeller is modified by separating one of the side shrouds from the diffuser vanes thereby creating a recirculation flow path around the vanes from the outside high pressure to the inside low pressure side.

On the Energy Transfer in Centrifugal Compressors

Abstract: In the layout and calculation of centrifugal compressors there are still considerable uncertainties when it comes to the theoretical determination of energy transfer from the impeller to the flowing medium and to the subsequent energy conversion in the diffuser. These problems arise particularly where compressor stage design with high pressure ratios and mass flow rates are concerned. A solution to these questions can presumably be found only through a physically balanced interpretation of the extremely complex flow mechanisms in the impeller. Since purely theoretical methods have hardly led to any reliable conclusions concerning the criteria of flow separation in the impeller or the secondary character of the impeller flow, there is still little knowledge about the creation of the jet-and-wake zones in the impeller and their decay (associated with large losses) in the connected diffuser. In studying the energy conversion process in the stage as a whole, great attention has to be devoted to the effects of the momentum exchange directly downstream the impeller. Hence the only possible way of solving these problems seems to be specific experimentation. For high flow velocities, this necessitates a special nonsteady measuring technique which also gives information about the relative flow in the rotating impeller.Copyright © 1974 by ASME

Expander open cycle gas dynamic laser

Abstract: This device includes an expander open cycle gas dynamic laser wherein the majority of the gas dynamic laser flow is recirculated while a fraction of the flow is removed in a boundary layer bleed removal system. This device includes a combustor for providing the proper gas constituents which then flow downstream of a nozzle means in a laser cavity to permit lasing to occur. The flow from the lasing cavity is directed into a diffuser which in turn directs its flow into the inlet of a compressor after flowing over a heat exchanger which cools the flow. One heat exchanger is in the bleed flow while the other is in the flow from the diffuser. The flow from the compressor is directed into the combustor.

The performance of a branched annular diffuser system

Abstract: Low-speed tests have been carried out on a branched annular diffuser system having a geometry similar to that employed in some gas turbine engine combustion systems. The system comprised a straight walled pre-diffuser followed by a sudden area expansion in which the flow was divided between two concentric annuli separated by a bluff body simulating a combustion chamber. The overall geometric area ratio was maintained at 2.0 and all tests were carried out with fully developed flow at inlet. The design flow split between the outer and inner annuli was 2.15:1. The system was tested with five different pre-diffuser geometries to show the effect of increasing the area ratio, increasing the included angle and canting the pre-diffuser. For each pre-diffuser geometry the influence of varying the flow split and the axial distance between pre-diffuser outlet and combustion chamber head (dump gap) were investigated. In addition to determining the overall performance characteristics, the pressure losses for the inner and outer flow fields were calculated and the losses further sub-divided in order to identify regions of high loss. [Continues.]

Ejector mixer - with component streams combined at mixing chamber inlet

Abstract: In an ejector mixer for gases and/or liquids of the type having annular coaxial nozzles leading to an annular mixing chamber which in turn becomes a diffuser, three annular nozzles are provided with a device for supplying one of the components to be mixed to the central annular nozzle and the second component to the inner and outer annular nozzles, at the inlet to the mixing chamber the stream of the first component being enveloped in the two streams of the second component. Specif. the inner walls of the central nozzle may be provided with resonance chambers at the critical section of the nozzle.

Performance of a short annular dump diffuser using wall trailing-edge suction

Abstract: A short annular dump (abrupt flow area change) diffuser was tested with suction through wall trailing-edge slots at inlet Mach numbers of 0.19 and 0.27 and at near ambient inlet temperature and pressure, with suction flow varied from zero to 10 percent of the inlet air mass-flow rate. The overall ratio of diffuser exit area to inlet area was 4.0, and the ratio of length to inlet height was 2.0. By applying suction flow separately on either wall or to both walls simultaneously, the original annular jet profile could be altered to either a hub- or tip-biased profile. Diffuser effectiveness was increased from about 25 percent with no suction to 50 percent at 6 percent outer-wall suction and to 52 percent at a combined suction rate on both walls of 10.25 percent. At the same time, diffuser total pressure loss was reduced by one-fourth.