Showing papers on "Diffuser (thermodynamics) published in 1968"

Subsonic diffusers designed integrally with vortex generators.

Abstract: A short subsonic diffuser has been developed incorporating vortex generators as an integral design feature. The principle of operation is that line vortices, when suitably arranged, mutually interact to drive each other towards an adjacent plane wall. The wall may then be pulled away from the vortices at such a rate that the vortices remain a constant distance from it. The ideal arrangement, having the vortex lines running along the edge of the boundary layer, can thus be obtained by design. A simple, two-dimensional diffuser was developed at Lockheed using these principles. It was compared experimentally with a conventional high-performance trumpet-shaped diffuser. Two significant results were observed in this test series. One was that both pressure recovery losses and distortion were reduced by about 40% by the new design. The other was that vortex generator design mismatches carry larger penalties with the integrally designed diffuser than with the conventional type. The subsonic diffuser of an inlet for a Mach 2.7 supersonic transport airplane was shortened and redesigned in two stages, using the integrated vortex generator approach. First, vortex generators were tailored to a short subsonic diffuser of conventional design, and then a new inlet was tested which included a subsonic diffuser designed on the integral basis. The successive changes improved both pressure recovery and flow uniformity. Thus, the basic concept was validated in a practical application.

Variable area diffuser for compressor

Abstract: 1,231,152. Centrifugal compressors. DRESSER INDUSTRIES Inc. March 3, 1969 [March 11, 1968], No.11256/69. Heading F1C. In a centrifugal compressor comprising an annular diffuser passage 20, Fig. 1, between the impeller 14 and a discharge chamber 13, a wall part 21 is movable to vary the axial width of the diffuser passage. The wall part 21 is connected via four cylindrical posts 23 to a control ring 32 which can be partially rotated in either direction on ball bearings 42 to control the axial position of the wall part 21. Each post 23 is slidably connected to a cam in the form of a helical web 36 extending circumferentially around parts of the ring 32 and having an arcuate slot 37 which receives a stud 26 carrying a pair of washer-like bearing members 38, e.g. of bronze, having bosses (39), Fig.3 (not shown), extending into the slot. The ring 32 is moved by an arm 40, e.g. in accordance with a compressor operating condition. Gas circulation around the back of the wall part 21 is prevented by seal rings 27, 28. Pressure balancing passages 29 are provided through the wall part 21.

Vehicle safety assembly having inflatable confinement

Abstract: A safety assembly for protecting an occupant of a vehicle comprises an inflatable confinement having a collapsed inoperative condition and an expanded operative condition, a diffuser member, and a fluid reservoir, the confinement being inflated by the flow of fluid from the reservoir through the diffuser member into the confinement. The length of the diffuser member is relatively smaller than the length of the confinement, and the diffuser member is provided with louvered slots for distributing and preferentially directing the flow of fluid therefrom so as to increase the ''''effective'''' length of the diffuser member and to reduce the frontal velocity of the confinement as it expands.

Variable Geometry Gas Turbine Radial Compressors

Abstract: An examination of the various mechanical and aerodynamic methods of flow and pressure regulation through high-speed, single-stage radial compressors is presented. Performance testing of a small gas turbine radial compressor with a variable vaned diffuser system is described. Methods of combined geometry variation to obtain minimum reduction of efficiency with flow variation are suggested based upon theoretical matching studies.Copyright © 1968 by ASME

Spurious Pressure Fluctuations in Wind Tunnels

Abstract: Wall pressure spectra measured in wind tunnels usually exhibit a pronounced rise at low frequencies, in conflict with theoretical predictions and with those experiments carried out without the constraint imposed by the wind tunnel Some wind tunnel experiments are described to show that typically the spurious disturbances arise in the first diffuser and travel upstream as acoustic waves Removal of the diffuser produces a spectrum falling at low frequencies

Closed cycle device

Abstract: This arrangement includes a gas dynamic laser wherein the lasing fluid is recirculated in a closed loop The flow can be assumed to start with the lasing gas passing through a cascade of supersonic nozzles This low pressure, high velocity gas is then passed through a lasing cavity where the lasing action takes place The energy of the high velocity gas stream is converted back to static pressure in a supersonic diffuser The diffuser is constructed with (1) variable geometry, and (2) provisions for bleeding off the boundary layer for improved efficiency Downstream of the supersonic diffuser there is a heat exchanger which partially cools the gas in the loop This partially cooled gas is then supplied to a compressor where the pressure and temperature are raised back to the level at the start of the flow The lasing gas is directed from the exit of the compressor to a manifold upstream of the cascade of supersonic nozzles The compressor only supplies a pressure rise equal to the pressure loss by inefficiencies in the nozzle, the supersonic diffuser and the pressure drop in the heat exchanger and plumbing To provide for cooling of the compressor, the gas bled from the diffuser is cooled by a second heat exchanger and pumped back to compressor inlet pressure and introduced into the compressor for cooling In steady state operation, both heat exchangers referred to above, are designed to regulate the nozzle inlet gas temperature by removing the amount of heat energy added by compressing minus the amount of energy extracted in the lasing beam and energy lost to the environment The compressor and pumping means for cooling the compressor can be driven by any means desired

Air compressor surge control apparatus

Abstract: 1,223,490. Axial-flow compressors. BENDIX CORP. Dec.30, 1968 [Jan.2, 1968], No.61643/68. Heading F1C. [Also in Division G4] Surge control apparatus for a multi-stage axialflow compressor 24, Fig. 1, of a gas turbine engine 20, comprises a normally closed air bleed valve 72 which is opened when surge is imminent in accordance with the relationship Ptx-Psx# K(Pt 3 -Pt 2 ), where Pt 3 is pressure derived from compressor outlet total air-pressure, Pt 2 is compressor inlet total air-pressure, Ptx and Psx are air-pressures derived from total and static air-pressures respectively both taken at the compressor inlet or outlet, and K is a constant. Inlet total pressure and outlet total and static pressures are communicated to first, second and third diaphragm-separated chambers 36, 38, 40 respectively through lines 52, 56, 60 to regulate the position of a servovalve 46 controlling the venting through line 86 of pressurized air from a chamber 84 to control the pressure Px therein and thereby control the air bleed valve 72. In an alternative embodiment, Fig.2 (not shown), the first diaphragm-separated chamber contains an evacuated bellows (116) connected to the diaphragms and to a lever-type servovalve (122) by a rod (114). Moreover, the first chamber is connected to the inlet and outlet total pressures through a respective restrictor, the second chamber is connected to outlet total pressure, and the third chamber is connected to outlet static pressure. The latter two pressures may be sensed in a Venturi (102) or in a diffuser. In another embodiment, Fig.3 (not shown), the first chamber is connected to the inlet static and outlet total pressures through a respective restrictor, the second chamber is connected to the inlet static pressure, and the third chamber is connected to the inlet total pressure. A final embodiment, Fig. 4 (not shown), employs fluidic means to directly control the pressure differential across a diaphragm (200) controlling the air bleed valve, the power jet of the fluidic means being subjected to two opposing transverse control jets connected respectively to inlet total pressure and, through respective restrictors, to inlet static and outlet total pressures.

Pressure suppressing arrangement

Abstract: A NUCLEAR STEAM GENERATING PLANT IS DISCLOSED WHICH IS ENCLOSED WITHIN A CONTAINMENT STRUCTURE WHICH EMPLOYS THE MELTING OF A SOLID MATERIAL SUCH AS ICE FOR PRESSURE SUPPRESSION AND HEAT ABSORPTION PURPOSES. AN ANNULAR DIFFUSER SECTION IS SITUATED BENEATH AN ANNULAR SOLID MATERIAL CONTAINING COMPARTMENT TO PROHIBIT EXCESS COOLANT ESCAPING FROM THE REACTOR AFTER AN ACCIDENT FROM OVERLOADING AND CHANNELING THROUGH VERTICAL SECTIONS OF THE MELTABLE SOLID. THE DIFFUSER SECTION COMPRISES A PLURALITY OF LIQUID TRAPS WHICH ACT AS VALVES, I.E., EACH TRAP FILLS WITH LIQUID AND IS ESSENTIALLY SEALED AFTER A RATED LOAD OF ESCAPING COOLANT HAS MELTED A PORTION OF THE VERTICAL SECTION OF SOLID MATERIAL ABOVE IT TO ENSURE THE EXPOSURE OF OTHER SECTIONS OF SOLID MATERIAL TO THE ESCAPING COOLANT.

A Photographic Study of the Three-Dimensional Flow in a Radial Compressor

Abstract: In order to visualize the three-dimensional flow in the impeller and the vaneless diffuser of a centrifugal compressor, water is used as the working fluid and streak lines of colored water are photographed and examined. The test is made at an extremely low speed so that streak lines do not diffuse due to turbulent mixing. The streak lines clearly demonstrate several types of secondary flow, some of which agree with what have been speculated to exist in actual compressors. Most of observed secondary flow patterns are qualitatively understandable with existing theories.

Vehicle safety apparatus

Abstract: A SAFETY APPARATUS INCLUDES A RESERVOIR CONTAINING FLUID UNDER PRESSURE, MEANS FOR OPENING THE RESERVOIR UPON THE OCCURRENCE OF A COLLISION, A DIFFISER FOR DIRECTING THE FLKOW OF FLUID FROM THE RESERVOIR, AND A CONFINEMENT ADAPTED TO BE INFLATED FROM A COLLAPSED CONDITION TO AN EXPANDED CONDITION IN WHICH THE CONFINEMENT IS OPERATIVE TO RESTRAIN AN OCCUPANT OF A VEHICLE AGAINST MOVEMENT RESULTING FROM A COLLISION. THE RELATIONSHIP BETWEEN THE DIFFUSER AND THE RESERVOIR IS SUCH AS TO RESULT IN A DIRECTING OF THE FLOW OF FLUID FROM THE RESERVOIR WITHOUT AN UNDUE RESTRICTION OF THE FLOW. THE PRESSURE-VOLUME RELATIONSHIP BETWEEN THE FLUID IN THE RESERVOIR AND THE FLUID IN THE INFLATED CONFINEMENT IS SUCH AS TO PROVIDE SUFFICIENT FLUID FOR INFLATING THE CONFINEMENT AND ABSORBING THE KINETIC ENERGY OF AN OCCUPANT ENGAGING THE INDATED CONFINEMENT DURING THE COLLISION.

Hydraulic pump-motor combination

Abstract: 1,243,453. Centrifugal pumps. WESTINGHOUSE ELECTRIC CORP. March 18, 1969 [March 28, 1968], No.14097/69. Heading F1C. A pumping arrangement, e.g. for hot liquid metals, comprises a pump 16 removably mounted in a container 12 having inlet means 90, 94 and outlet means 76, 98. The pump has concentric inlet and outlet ports 70, 68 respectively, formed by bowl-shaped members 66, 64 which slidably engage the container inlet tube 90 and concentric discharge cone 76 to facilitate disconnection and removal of the pump from the container via an opening in a supporting concrete structure 10. The sliding engagement also permits relative axial movement between the pump and container due to temperature changes. The discharge passage of the pump has diffuser vanes 62 and swirl-reducing vanes 74 therein. The liquid level in a leakage-receiving portion of the container is controlled by an overflow pipe 120, and the space above the liquid is filled with inert gas such as argon. Swirl-preventing vanes 118 are provided at the gas-liquid interface. A shaft bearing 50 receives pressurized liquid through conduits 84. The pump may be a single stage centrifugal or mixed-flow pump or a multi-stage centrifugal pump.

Fluid logic element

Abstract: 1,219,003. Fluid logic elements. SOC. BERTIN & CIE. 10 April, 1968 [21 April, 1967; 28 Feb., 1968], No. 17244/68. Heading G4P. A fluid logic element has a reflection chamber 10 with converging walls 17a, 17b, so that when a control channel 6 is actuated, a fluid jet from nozzle 8 is reflected from one of the walls to cause unequal pressures in the chamber whereby the stream is switched to that outlet channel on the same side of the chamber as the actuated control. The device is bi-stable when nozzle 8 is symmetrically disposed and the walls 17a, 17b equally inclined, and monostable when one of the outlets is preferred due to symmetry bias of the nozzle (Fig. 3, not shown) or to unequal inclination of the walls (Fig. 12, not shown). One of the control channels of the monostable device may be replaced by two channels (20), (21), Fig. 5 (not shown) to provide an AND/ NAND gate or, alternatively, by several channels each connected to a cylindrical fluid diode with a central orifice, closure of any one of which causes back pressure switching to the unpreferred outlet channel, thus providing an OR-NOR gate (Fig. 7, not shown). The channels (20), (21) may each have an injector (32) with a larger cross-section diffuser (33) to provide a valve to prevent back pressure from causing undesirable "flip-flopping" (Fig. 11, not shown). Negative feedback connections between outlet and control channels or the chamber 10 may be introduced to enhance stability (Figs. 13, 14, not shown) and isolating circuits, Fig. 15 (not shown), forming fluid diodes, may be connected to one or more of the control channels to prevent back pressure in the chamber 10 from interfering with the control channels (Figs. 16, 17, 18, not shown). The logic element is formed of three plates of plastics, metal, or the like, the rear sheet being solid, the middle sheet having the fluid channels, and the front sheet having apertures formed therein for connection to tubing. The fluid may be liquid or gas.

Improvements in radial flow turbine

Abstract: 1,127,684. Boundary layer control. GENERAL ELECTRIC CO. 6 July, 1966 [16 July, 1965], No. 30432/66. Heading F2R. [Also in Division F1] In a radial outward flow turbine, two spaced discs 10, 12 form a shaft-supported rotor comprising in seriatim order an unobstructed, curved fluid inlet passage 13 to direct fluid under pressure radially outwardly in two-dimensional flow, highly cambered rotor blades 16 secured between the discs 10, 12 at a radial distance from the shaft 11 to receive fluid flowing outwardly in two-dimensional flow from the inlet passages, the discs and blades rotating as a unit in a direction opposite to the direction of camber of the blades, and a rotating vaneless diffuser passage 17 formed between the radial outer ends of the discs, a vaned diffuser 18 being radially spaced from the diffuser passage 17 and a collector or scroll 19 into which the fluid discharges surrounding the rotor. A built-in boundary layer control is provided by diffuser passage 17, the rotating side walls of the discs 10, 12 energizing the boundary layer due to the centrifugal field on any particle since all boundary layer particles will have a high tangential velocity approaching or equal to the rotational velocity of the discs. Stationary guide vanes 14, which may be adjustable, are provided in the inlet passage 13 radially inwardly of the blades 16 to impart a tangential velocity to the fluid. Since there is a significant pressure rise between the vaned diffuser 18 and the scroll 19, a boundary layer problem may be encountered. If so, control may be obtained by boundary layer control means provided in the walls of the vaned diffuser 18 and comprising suction or blowing means 20, or the walls may be porous.

Flow of a supersonic jet into channels of various shapes

Abstract: The author examines the process of flow from one or more supersonic nozzles into a chamber with a diffuser or a wide cylindrical tube. The characteristic regimes are established. An analysis of the experimental data shows that the chamber pressure is at a minimum when critical flow conditions exist at the diffuser outlet.

Experimental performance of a 5-inch /13 cm/ axial-flow turbine over a range of Reynolds number

Abstract: Efficiency, mass flow rate, torque, and exit diffuser effectiveness of 5-inch axial flow turbine

Improvements in radial flow fluid machine

Abstract: 1,115,617. Boundary layer control. GENERAL ELECTRIC CO. 17 Sept., 1965, No. 39864/65. Heading F2R. [Also in Division F1] In a radial flow compressor (see Division F1), the boundary layer of the air flow through a vaned diffuser 18 is controlled by suction or blowing means 20 or by porous walls of the diffuser.

An investigation of ejector systems using very large diffusers

Abstract: : An experimental investigation was conducted to determine the characteristics of ejector systems using very large cylindrical diffusers Tests were conducted with nitrogen, carbon dioxide, and helium gases in systems having diffuser cross section to nozzle throat area ratios from 950 to 15,300 Limited effects of ejector nozzle configuration, diffuser length, system size, and diffuser wall cooling were investigated Excellent system performance was obtained, with test cell altitudes of 250,000 ft being produced by the pumping action of the ejector at nozzle total pressures of approximately 100 to 200 psia

Multi-stage system

Abstract: A high power gas dynamics laser device having multiple expansion-diffusion stages for gas flow and multiple relection optic having a plurality of passes for the generation of laser power The gaseous working fluid is provided by a combustion system The combustion products are expanded through nozzles to obtain a population inversion and then a diffuser is used to recover the dynamic pressure The gas flow follows four stages, the first three stages are single expander-diffuser units in series and the fourth stage is a larger sized stage having flow in two parallel expander-diffuser units The nozzles of the first three stages are sized and contoured to obtain pressure in their laser cavities which are as equal as possible and the nozzle exit Mach No is made approximately equal

Friction in the preseparation zone and heat transfer in the separation zone of a turbulent boundary layer in the flow of heated air in a diffuser with cooled walls

Abstract: The friction in the preseparation zone and the heat transfer in the separation zone of turbulent boundary layer have been experimentally investigated for flows of heated air in diffusers with cooled walls. An experimental method of determining the separation point is proposed together with a criterial equation for calculating the heat transfer in the separation zone.

Apparatus for and method of regulating the output power of gaseous lasers

Abstract: There is described a method of and apparatus for regulating the output power of lasers of the type utilizing a heated high velocity flowing gas. The method and apparatus comprise a plurality of separate sources of the gas in combination with a segmented diffuser section wherein at least one but not all of the diffuser sections can be blocked to selectively permit use of all or less than all of the gas sources, thereby permitting regulation of output power by regulating the mass flow through the optically resonant cavity disposed between the sources of gas and the diffuser.

Effect of Secondary Injection on the Characteristics of a Supersonic Parallel Diffuser

Abstract: This paper reports further progress in evaluating the performance of the supersonic parallel diffuser incorporating a sudden entry enlargement which provides for the injection of secondary fluid. The effects of introducing proportions up to 10 per cent of the primary flow in a two-dimensional diffuser are illustrated by schlieren photographs of the flow patterns and by measurements of the local wall static pressure and heat transfer distributions. The normal and oblique shock regimes (corresponding respectively to the unstarted and started conditions) are modified by the strengthening of the weak shock system generated at the primary nozzle mouth. Optimum overall static pressure recovery is reduced by the admission of secondary fluid, though the conditions under which it is achieved remain unchanged unless forced injection is used. The local heat transfer no longer follows the static pressure distribution and in the unstarted diffuser large peaks occur near mid-length. Over an intermediate range of Reynol...

Determination of flow in an axial-to-radial diffuser with swirl.

Abstract: The parameters affecting the efficient design of a^xialtoradial diffusers, are discussed and a selection made of those to be investigated. A model diffuser v/.as constructed based on the geometry of a jet impinging on a flat plate v7ithout internal vanes. Various amounts of sv/irl v;ere introduced on a constant flow rate and the recovery of the diffuser for thes.e conditions noted. The internal flow v;as mapped photographically and with pressure probes. The results are given in the form of static pressure plots along the diffuser xjalls , velocity profiles, and calculated diffuser efficiency, The maximum efficiency of 91.7% occured at just under tlie raaxira.um sv;irl used, based on a calculated inlet pressure. A detailed program for additional testing is given. Thesis Siipervisor: D. G. Wilson Title: Associate Professor of Mechanical Engineering