US3591084A - Fluid ejector particularly for cushion levitated devices - Google Patents

Fluid ejector particularly for cushion levitated devices Download PDF

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Publication number
US3591084A
US3591084A US758491A US3591084DA US3591084A US 3591084 A US3591084 A US 3591084A US 758491 A US758491 A US 758491A US 3591084D A US3591084D A US 3591084DA US 3591084 A US3591084 A US 3591084A
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United States
Prior art keywords
nozzle
wall member
outlet
fluid
air
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Expired - Lifetime
Application number
US758491A
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English (en)
Inventor
Bengt Johan Anders
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saab AB
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Saab AB
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Filing date
Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/06—Air-cushion wherein the cushion is formed within plenum chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/04—Air-cushion wherein the cushion is contained at least in part by walls
    • B60V1/043—Air-cushion wherein the cushion is contained at least in part by walls the walls being flexible
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
    • F15C1/00—Circuit elements having no moving parts

Definitions

  • the mixing chamber in which secondary fluid was educted into and mixed with primary fluid extended generally in the same direction as the nozzle from which the primary fluid issued, and the mixing chamber opened into a diffuser that extended further in the same direction and comprised in effect an axial extension of the mixing chamber.
  • the mixing chamber it was usually necessary that the mixing chamber have considerable length in the direction of flow.
  • the diffuser into which fluid flowed from the mixing chamber, and in which it expanded and decelerated, also had to have substantial length in the flow direction, due to the necessary limitation of the opening angle of the diffuser.
  • the general object of the present invention is to provide an ejector that has relatively small extension in the direction of flow of primary fluid out of the nozzle, and which is therefore. adaptable to structures which do not permit incorporation of an ejector of the heretofore conventional type wherein the mixing chamber and diffuser were substantially elongated in said direction.
  • Another object of this invention is to provide an ejector of the character described which is especially well adapted'for an air cushion device or ground effect machine, whereby a relatively high speed but small volume stream of primary air, provided by a pump or the like, can be utilized to educt secondary air from the ambient atmosphere, andvwherein the primary and secondary air are mixed to produce a large volume of rela- 4 tively slowly flowing high-pressure air that can be expelled from the ejector for efficient maintenance of an air cushion beneath the device, by which the device is levitated.
  • FIG. 1 is a more or less diagrammatic vertical sectional view of an ejector constructed in accordance with the principles of this invention, illustrating the fluid flows in the same;
  • FIG. 2 is a view generally similar to FIG. I but illustrating a modified embodiment of the invention
  • FIGS. 3 and 4 are perspective views of other modified embodiments of the invention.
  • FIG. 5 is a plan view of an airborne load supporting pallet incorporating an ejector that embodies the principles of this invention
  • the numeral 5 designates generally an ejector according to the invention, comprising, in general, a pair of wall members 6 and 7 that have opposing spaced apart surfaces, and a nozzle 8 for primary fluid that has its axis substantially normal to the two wall members, opens through the wall member 6, and has its mouth 9 spaced from the wall member 7.
  • the wall member 7 extends across the mouth of the nozzle at a distance therefrom, it divergingly deflects the primary fluid issuing from the mouth of the nozzle so that streams thereof flow in opposite directions between the wall members.
  • the primary fluid flows away from the nozzle between the wall members, it first passes through a mixing chamber or mixing zone 10 in the neighborhood of the nozzle, in which secondary fluid is educted through inlet means 11 in the wall member 6, and thence the mixed primary and secondary fluids flow into a diffuser zone 12 at a greater distance from the nozzle.
  • the ejector has a relatively small extension in the direction of the nozzle axis.
  • the wall member 6 through which the primary fluid nozzle 8 opens has an outwardly convergent frustoconical portion 14 that is concentric to the nozzle and which terminates in a liplike inner edge 15 that is spaced from the nozzle all around the same to provide an annular secondary fluid inlet means 11.
  • the mixing chamber 10 in the FIG. 1 embodiment of the invention is effectively convergent in the direction of fluid flow therethrough.
  • both wall members 6 and 7 can be flat over their entire areas, and in addition to an annular inlet means 11 for secondary fluid around the nozzle, the wall member 6 can have holes 11 therein at different radially. spaced distances from the nozzle axis to provide further secondary fluid inlet means.
  • the diverging deflection of the primary fluid issuing from the nozzle 8 can be controlled to suit particular requirements.
  • the fluid streams moving through the mixing chamber 10 and the diffuser 12 are substantially confined to flow in a pair of opposite directions by reason of the nozzle 8 being rectangular in cross section, with a high ratio of length to width, and the secondary fluid inlet means II likewise being elongated and extending mainly along the longer sides of the nozzle.
  • the nozzle 8 is circular in cross section
  • the secondary fluid inlet means 11 is annular and surrounds the nozzle
  • the wall members 6 and 7 are likewise circular in outline; hence the direction of fluid flow is radial in all directions from the nozzle axis.
  • That portion of the space between the wall members 6 and 7 that is nearest the nozzle serves as a mixing chamber 10
  • that portion of the space between the wall members that is farther from the nozzle serves as a diffuser 12
  • the configuration of the wall members and the spacing between them, as well as the arrangement of the secondary fluid inlet means 11 can all be designed to afford desired conditions of mixture, pressure and velocity of the fluids.
  • FIGS. 5 and 6 illustrate an ejector 5 of this invention embodied in an air cushion levitated load supporting pallet 17.
  • the wall members 6 and 7 of the ejector are octagonal in planform, the wall member 6 through which the nozzle extends being uppermost and of somewhat greater size than the wall member 7.
  • a load supporting platform 18, which can be of the same size as the upper wall member 6, is mounted on top of the upper wall member on suitable spacers l9, and the space between said wall member and the platform is made high enough to admit the fork of a forklift truck.
  • the nozzle 8 in the FIGS. 5 and 6 embodiment comprises the downtumed end portion of a tube 21, projecting concentrically down into a central opening in the top wall. Along most of its length the tube 21 overlies the upper surface of the top wall, to which it is attached by means of clips 23.
  • the tube terminates near the periphery of the top wall in a suitable fitting 24 by which it can be connected with an airhose 25 or the like that communicates with a suitable source of pressure air.
  • the central hole in the top wall member has a gently rounded lip 26 (see FIG. 6) which cooperates with the nozzle 8 to provide an annular secondary fluid inlet 11 through which atmospheric air is drawn into the space between the wall members 6 and 7.
  • a hollow inflatable skirt 30 Connected with the peripheries of the upper and lower wall members respectively are the outer and inner walls 28 and 29 of a hollow inflatable skirt 30 that surrounds the wall members.
  • the skirt projects beneath the lower member 7 and cooperates with the undersurface thereof and with the surface therebeneath to define a plenum 31. Air from the ejector flows through the skirt and out of the same through outlet ports 32 in its bottom to generate in the plenum 31 a pressure fluid cushion by which the device is levitated.
  • the hose 25 can be connected with a source of compressed air or the like at considerably higher pressure than that required for the air cushion upon which the device is supported.
  • a source of compressed air or the like issues from the nozzle 8 in a relatively high velocity stream and educts atmospheric air through the secondary air inlet means 11.
  • the primary and secondary fluids are of course mixed in the mixing chamber 10, expanded in the diffuser zone 12 and thence issue in all directions laterally into the inflatable skirt. Because of the mixing of secondary atmospheric air with the primary highpressure air, only a relatively small rate of flow of high-pressure air is required and suitable pressure air sources are therefore readily available.
  • FIG. 7 illustrates an ejector 5 of this invention embodied in an air cushion vehicle or ground effect machine, to provide the air intake thereof.
  • the upper and lower wall members 6 and 7 are circular in planform, but their marginal edge portions are curved downwardly.
  • the space between them opens downwardly into an inflatable hollow skirt 30 that extends all around the vehicle to define a plenum 3] therebeneath.
  • the outer wall 28 of the hollow skirt is secured to the outer edge of the upper wall member 6, and its inner wall29 is secured to the undersurface of the bottom wall member 7, inwardly of the downturned marginal edge portion thereof.
  • the skirt has air outlets 32 in its bottom.
  • the upper wall member has a central opening defined by an upturned circumferential lip 26', and the nozzle 8 comprises a short tube that is suspended from the lip 26 by radial braces 35.
  • the nozzle 8 and the lip 26' of course cooperate to define an annular secondary fluid inlet means 1 1.
  • An engine unit 37 supported by radial braces 38 in the upper portion of the nozzle, drives a fan 39 which is concentric to the lower portion of the nozzle tube and by which air is drawn down through the tube and propelled against the lower wall member 7, which of course deflects it radially outwardly in all directions.
  • a plurality of ejectors of this invention can be firmly connected in side byside relation to a single load supporting platform, or to the hull of a single air cushion vehicle, to provide a high degree of lift and stability.
  • this invention provides an efficient ejector which is of short extension in the direction of flow of primary fluid thereinto and which is thus well adapted for use in air cushion levitated devices as well as for other applications in which it is undesirable to use a heretofore conventional ejector because ofits length in said direction.
  • An ejector comprising:
  • a first wall member having a surface which is transverse to the nozzle axis and which is spaced from and faces the nozzle outlet and extends substantial distances to outlet zones spaced to opposite sides of the nozzle, all portions of said surface that lie between said outlet zones and a zone axially opposite the nozzle outlet being continuous, unobstructed and substantially flat so that fluid which has issued from the nozzle flows divergently in straight paths along saidsurface for substantial distances in opposite directions transverse to the direction of flow that it had upon issuing from the nozzle outlet; and
  • a second wall member having a surface which is also generally transverse to the nozzle axis and which opposes and is spaced from said surface of the first wall member to cooperate therewith in confining fluid to flow in said opposite directions, said second wall member having a medial aperture therein through which the outlet portion of the nozzle projects and having inlet means therein through which secondary fluid can be educted into the primary fluid.
  • said aperture in the second wall member through which the outlet portion of the nozzle projects being larger than the outlet portion of the nozzle and being coaxial therewith so that the edge of said aperture is spaced from the nozzle all around the same to define said inlet means.
  • outlet means at which said wall members terminate and into which the space between them opens, said outlet means projecting beneath and extending around said first wall member to cooperate with its undersurface and a surface therebeneath in defining a plenum in which fluid emitted from the outlet means forms a cushion that supports the device.
  • An air cushion supported device of the type comprising a bottom wall member that defines a downwardly facing surface, means extending around said bottom wall member and projecting beneath said bottom surface thereof to cooperate with said surface and a surface therebeneath in defining a plenum, and outlet means at the bottom of the device from which air is emitted into the plenum to maintain an air cushion therein, said device being characterized by:
  • said upper wall member having inlet means therein adjacent to the mouth of the nozzle through which secondary air can be educted into primary air flowing between the wall members;
  • C. means communicating the space between the wall members with said outlet means, the last named means being connected with the wall members and comprising said means extending around the bottom wall member.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Transportation (AREA)
  • Theoretical Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Jet Pumps And Other Pumps (AREA)
US758491A 1967-09-11 1968-09-09 Fluid ejector particularly for cushion levitated devices Expired - Lifetime US3591084A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE12475/67A SE301090B (de) 1967-09-11 1967-09-11

Publications (1)

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US3591084A true US3591084A (en) 1971-07-06

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Family Applications (1)

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US758491A Expired - Lifetime US3591084A (en) 1967-09-11 1968-09-09 Fluid ejector particularly for cushion levitated devices

Country Status (3)

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US (1) US3591084A (de)
FR (1) FR1595581A (de)
SE (1) SE301090B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4114097A1 (de) * 1991-04-30 1992-11-05 Thiemt Ohg Geb Vorrichtung zur pulverbeschichtung
US20050016783A1 (en) * 1999-06-15 2005-01-27 Arbortech Industries Ltd. Air board
US10155507B2 (en) * 2016-01-28 2018-12-18 Vescovi Innovations, LLC Compressed gas levitation device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3034730A (en) * 1957-09-27 1962-05-15 Pilo Means for the distribution of a liquid on rotating surfaces
US3439875A (en) * 1966-11-16 1969-04-22 David Corbet Randall Application of chemical substances over large areas

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3034730A (en) * 1957-09-27 1962-05-15 Pilo Means for the distribution of a liquid on rotating surfaces
US3439875A (en) * 1966-11-16 1969-04-22 David Corbet Randall Application of chemical substances over large areas

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4114097A1 (de) * 1991-04-30 1992-11-05 Thiemt Ohg Geb Vorrichtung zur pulverbeschichtung
US20050016783A1 (en) * 1999-06-15 2005-01-27 Arbortech Industries Ltd. Air board
US7210549B2 (en) * 1999-06-15 2007-05-01 Arbortech Industries Ltd. Air board
US10155507B2 (en) * 2016-01-28 2018-12-18 Vescovi Innovations, LLC Compressed gas levitation device
US10752233B2 (en) 2016-01-28 2020-08-25 Vescovi Innovations, LLC Method for levitation of an object

Also Published As

Publication number Publication date
FR1595581A (de) 1970-06-15
SE301090B (de) 1968-05-20

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