US3001691A - Jet operated device for circulating or compressing a fluid - Google Patents

Description

Sept. 26, 1961 B. J. M. SALMON ETAL 3,001,691

JET OPERATED DEVICE FOR CIRCULATING OR COMPRESSING A FLUID Filed Jan. 6, 1959 3 Sheets-Sheet 1 INVENTORS BENJAMIN JEAN MARCEL SALMON 8| JEAN HENRI BERT! Sept. 26, 1961 B. J. M. SALMON ETAL 3,001,691

D DEVICE FOR CIRCULATING OR COMPRESSING A FLUID JET OPERATE Filed Jan. 6, 1959 3 Sheets-Sheet 2 INVENTORS BENJAMIN JEAN MARGEL 'SALMON 8| JEAN HENRI BETIN Sept 1951 B. J. M. SALMON ErAL 3,001,691

JET OPERATED DEVICE FOR CIRCULATING OR COMPRESSING A FLUID Filed Jan. 6, 1959 3 Sheets-Sheet 3 INVENTORS BENJAMIN JEAN MARCEL SALMON 8 JEAN HENRI TIN BY I United States Patent 3,001,691 JET OPERATED DEVICE FOR CIRCULATING 0R CONIPRESSENG A FLUID Benjamin Jean Marcel Salmon, Suresnes, and Jean Henri Bertln, Neuilly-sur-Seine, France, assignors to Societe Bertin & Cie, Paris, France, a company of France Filed Jan. 6, 1959, Ser. No. 785,279 Claims priority, application France Jan. 9, 1958 2 Claims. (Cl. 230-108) The transfer of energy from a primary or energizing flow to a secondary or induced flow to drive the latter flow, can be carried out in two different well known ways: (a) by tangential action and mixture, in continuous operation, or (b) by thrust or sandwiching, in intermittent flow.

The conventional jet ejector illustrated in FIG. 1 of the accompanying drawings in an example of (a) and comprises a mixing chamber 2 following the nozzle 1 discharging the primary or energizing jet; the induced fluid is entrained, as shown by the arrows f into this chamber which is extended by a diffuser 3 opening into the zone to be fed.

This operation takes place with very poor efi'iciency owing to the losses due to the formation of the mixture and to the unavoidable vortices.

In the case of ([2), primary flow is no longer in the form of a continuous jet but in the form of a succession of pufls which push in front of them, as would a piston, slices of secondary fluid enclosed between the puffs.

FIG. 2 of the accompanying drawings illustrates a device of this kind.

A puflf of primary fluid is shown at 4 as it issues from the nozzle 1. It drives in front of it, through the convergent-divergent duct 5, a slice of secondary fluid 6 behind the previous puff 4a which itself pushes before it the previous slice of secondary fluid 6a, which lies behind an earlier puff 4b, and so on. Discharge takes place in the system to be fed, which is the atmosphere in the illus trated example, the device being then used to augment the thrust of the hot gaseous flow generated in a pulsatory combustion chamber.

This pulsatory drive, acting normally or perpendicularly to the sections of induced fluid, yields high efliciences, but may lead to technical diificulties.

The present invention has for its object to combine the normal action with the tangential action and to allow, starting with a permanent energizing jet and requiring but a relatively simple mechanical device, transfer to the induced flow of an important fraction of the available energy, by normal or frontal action.

In the accompanying drawings:

FIGS. 1 and 2 are explanatory diagrams which have been referred to above.

FIG. 3 is an axial section of an embodiment of the invention.

FIG. 4 is a section on an enlarged scale taken along the line IV-IV of FIG. 3, illustrating the generation of spirals formed by the energizing fluid.

FIG. 5 is an axial section of another embodiment with a helical jet.

FlGS. 6 to 9 are similar sections of four additional embodiments.

FIG. is a section of a detail of FIG. 9, on an enlarged scale, taken along line XX of this figure.

In the embodiment of FIGS. 34, a stationary casing is formed by two flanges 7 and 8 which converge slightly towards the periphery, i.e. whose spacing gradually decreases from the axis AA of the machine to the periphery, so as to keep a roughly constant radial passage area, as in a compressor. .The flanges comprise, along the axis, one or two inlets 9, 10 for sucking induced fluid and, at

3,001,692 Patented Sept. 26, 1961 their periphery, the flanges are connected to a volute 11 adapted to collect the compressed fluid. A hollow shaft 12 rotates about axi AA. This shaft is driven by a motor (not shown) and its bore 13 is fed with energizing fluid under pressure. This fluid issues from slot- like nozzles 14, 14a, which are directed parallel to the axis AA and which are located at the end of radial arms 15, 15a which are fast with the shaft 12. The energizing fluid is discharged by the slots 14, 14a in the form of two flat opposite jets which, during the continuous rotation of shaft 12, sweep the space comprised between the flanges 7 and 8 and extending around axis AA.

FIG. 4 illustrates this operation. Only one of the arms 15, rotating in the direction of arrow 1, and the corressponding slot 14 extending perpendicularly to the plane of the figure, have been drawn. One of the flanges 8, and the circle 8a corresponding to the connection of this flange with the volute 11, are seen. Owing to the composition of the tangential velocity u at which the slot 14 moves, with the velocity w of the ejected primary fluid relatively to the slot, the fluid issues with an oblique absolute velocity v and moves at this velocity through the space comprised between flanges 7 and 8. (The velocities are not drawn to scale on the figure because they are much too high and may reach several hundreds of meters per second.)

If the origin of time, or zero time, is taken as corresponding to the position of the members shown in FIG. 4, at the time z slot 14 was at a The fluid then ejected has reached at zero time, the distance a f being equal to the product of v by the time difference t At the time -2t slot 14 was at a and the fluid it has ejected has reached f at zero time, the distance a f being equal to the product of v by 2t and so on. Therefore, at zero time, the fluid previously ejected by the slot 14 lies on a spiral S This spiral moves through the space between flanges 7 and 8. At the time +1 slot 14 reaches (1' and the fluid spiral at 5' pushes in front of it, towards volute 11, the primary fluid which has entered through inlets 9 and 10.

The opposite slot 14a (not shown in FIG. 4) operates similarly: at zero time, the fluid ejected by this slot lies on a spiral S which moves in like manner.

The device thus constitutes a sort of centrifugal compressor with fluid vanes. As the spirals move, they exert a frontal action on the induced fluid and this frontal action is a cause of good efliciency.

The above explanation is, of course, theoretical since the inducing jet issuing from the slots is assumed to maintain it velocity. However, as the inducing fluid moves away from the slots, the jet formed at the outlet of the slots loses its stiffness, and it spreads out and deteriorates through tangential action and vertical mixture with the induced fluid. This action entails unavoidable losses, but the efliciency is higher than that which is obtainable with a purely tangential action as in the case of FIG. 1. On the other hand, it is convenient to be able to use a continuous inducing jet, contrary to the device of FIG. 2 which requires a pulsating jet.

ln the embodiment of FIG. 5, the nozzle 16 forming the inducing jet, rotatesabout axis AA which is parallel to the axis of said nozzle but is shifted radially, and is disposed at the inlet of a convergent-divergent duct 18 of revolution about axis AA and comprising a central body 19, so that the axis of the nozzle describes the medial line of an annular orifice 20 bounded by body 19 and the Wall 18.

Referring to the analysis shown in FIG. 4 (although in this case the flow is rather more complex since it does not lie in a plane), it will be observed that the flow of inducing fluid has a helical shape and propagates through the space comprised between the duct 18 and the central body, driving before it, by frontal and tangential action, the induced fluid entering the orifice 20. Duct 18 and central body 19 must be so shaped that the helical inducing jet sweeps'the space between these members while remaining tangential to them. Theoretically, the mean stream-line of the jet ought to describe (neglecting velocity retardation) a single-sheet revolution hyperboloid about axis AA. In practice, the spreading out of the jet and its retardation will be taken experimentally into account, in order to determine more accurately the adequate wall outlines.

It is advantageous to replace the cylindrical jet by a jet of rectangular shape or, better still, by a sheet-like jet issuing from a thin slot-like nozzle, as in FIGS. 3 and 4. The delimitation of the boundary between the inducing and induced flows is then effected in a more regular way, the separating surfaces having, at the start, rectilinear directrices (FIG. 6).

As in the case of FIG. 3, it is possible to use two or more nozzles 16, 16a (FIG. 7) rotating synchronously, to generate two or more inducing jets.

In the arrangement of FIG. 8, the nozzles 16, 16a generating the inducing jets are inclined with respect to the axis AA of the system, in a direction opposite to the direction of rotation so as to reduce the magnitude of the tangential component. This arrangement may be particularly useful in the case where the ejection velocity of the inducing jet is too small in comparison with the tangential linear velocity of the nozzles.

The same arrangement is easily applicable to the case of FIGS. 3 and 4, by imparting to the relative velocity w a tangential component, ie by using a nozzle whose blowing slot 14 is inclined with respect to the radius.

In the embodiment of FIGS. 9 and 10, the inducing jets in the form of flat sheets are generated by radial slots 22, 22a extending on hollow radial arms 23, 23a which are fast with the hollow rotary shaft 12. As shown in FIG. 10, the slots 22, 22a may be inclined in order to impart to the injection velocity of the inducing sheet a tangential component which, according to the direction of inclination, is subtracted from the rotation velocity of the nozzle, or is added thereto.

This inclination of the nozzles, such as that of the nozzles shown in FIG. 8, may be used to insure, by reaction, rotation of the shaft 12 carrying them, thus avoiding the use of a motor for driving this shaft.

The radial arms may, of course, be more numerous, for instance there may be 3 or 4 of them. They will preferably be so shaped as to reduce resistance to the induced fluid and possibly to have a favorable interaction with this fluid. Thus, reaction of the fluid on the arms may contribute to their rotation, provided they are shaped as motive vanes similar to turbine vanes, or else, the driving of the arms by a motor or by reaction of the inducing flows may contribute directly to driving the induced flow, provided the arms are shaped as compressor vanes or screw blades. This latter case is illustrated in FIG. 10.

A similar arrangement may be applied to the device of FIGS. 3 and 4, by fixing on shaft 12, close to the inlets 9 and 10, vanes or screw blades having a motive or compressive action as set forth above;

All the above-described devices may be operated both with liquid and gaseous flows; Mixed solutions can also be considered, with one of the flows being liquid and the other gaseous.

The applications of the invention are numerous.

The embodiment of FIGS. 3 and 4 is specifically directed to the case of a compressor or fan, whereas the other embodiments may be operated either as compressors or fans, or as jet propulsion units, or as aircraft sustainers or lift producers, the mixture of inducing fluid and induced air in that case issuing into the atmosphere. According to the particular application, the axis AA will be horizontal or vertical.

What we claim is:

1. An ejector device comprising, in combination, a longitudinally-extending duct having a peripheral wall with said wall defining a convergent inlet end for said duct and said duct being generally divergent away from said convergent inlet end, a hollow rotary shaft coaxial with said duct and disposed at said inlet end, a plurality of hollow vane-shaped arms integral with and extending radially from said hollow shaft toward said wall at said inlet end but the ends of said arms terminating short of said wall and the trailing edges of said vane-shaped arms extending substantially in the transverse plane of smallest cross-section of said duct wherein the convergent portion of said wall is connected to the divergent portion thereof, the interior of said hollow arms communicating with the interior of said hollow shaft, slot-like nozzles formed on said arms and extending along the trailing edges thereof, said nozzles communicating with the interior of said hollow arms, said shaft being adapted to be connected to a supply of fluid under pressure for supplying pressure fluid to said nozzles through the interior of said shaft and said arms, whereby the fluid in issuing from said nozzles forms thin laminar jets directed to move along said duct in a generally helical path.

2. An ejector device as defined in claim 1, wherein each slot-like nozzle is oriented in a direction which is inclined with respect to the radial plane of its arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,067,883 Skifflngton July 22, 1913 1,653,189 Oliphant Dec. 20, 1927 1,842,940 Jannin Ian. 26, 1932 1,900,898 Christie Mar. 14, 1933 FCREIGN PATENTS 561,787 France Aug. 17, 1923

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