Jet pump comprising an internal nozzle

Abstract

The invention relates to a jet pump collector comprising a convergent duct extending along the longitudinal axis (AX) and comprising an intake opening for a fluid to be withdrawn, this convergent duct having a restriction shape terminated by a reduced end having a smaller cross-section than its intake opening. This convergent duct is equipped with a tube (17) orientated perpendicular to the longitudinal axis longitudinal (AX), this tube (17) comprising an outer portion extending outside of the convergent duct and being terminated by an intake opening (31) for a propulsion fluid, and an inner portion extending in the convergent duct and comprising a plurality of distribution openings (18, 19) for the propulsion fluid which are orientated towards the reduced end.

Claims

1. A collector for a jet pump comprising a convergent duct extending along a longitudinal axis and comprising an intake opening for a fluid to be withdrawn, the convergent duct having a restriction shape terminated by a reduced end having a smaller cross-section than the intake opening, the convergent duct being equipped with a tube positioned between the intake opening and the reduced end, the tube comprising an outer portion extending outside of the convergent duct and being terminated by an intake opening for a propulsion fluid, and an inner portion extending in the convergent duct, the inner portion being orientated perpendicular to the longitudinal axis and comprising a plurality of distribution openings for the propulsion fluid which are orientated towards the reduced end, and wherein the inner portion of the tube has a tapered cross-section defining a tapered leading edge oriented towards the intake opening of the convergent duct.

2. The collector according to claim 1, wherein the inner portion of the tube has a rectilinear shape.

3. The collector according to claim 1, wherein the inner portion of the tube has a drop-shaped cross-section.

4. The collector according to claim 1, wherein the plurality of distribution openings consists of two distribution openings.

5. The collector according to claim 1, wherein the convergent duct has a conical shape.

6. The collector according to claim 1, wherein the reduced end has a cross-sectional area that is half a cross-sectional area of the intake opening.

7. A jet pump, comprising the collector according to claim 1, the collector having a cylindrical portion which is prolonged by a flare terminated by a discharge opening, wherein the reduced end of the convergent duct is prolonged by the cylindrical portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 already described, is a perspective view of a known jet pump;

(2) FIG. 2 already described, if an assembly view showing the incorporation of a jet pump and its pipes on the outer surface of an engine housing;

(3) FIG. 3 already described, is a sectional view of an engine showing the radially available space for incorporation of a jet pump;

(4) FIG. 4 is a perspective view of a jet pump tube according to the invention;

(5) FIG. 5 is a perspective view of a jet pump body according to the invention; and

(6) FIG. 6 is a perspective view of a jet pump according to the invention in its entirety.

DETAILED DESCRIPTION

(7) The basic idea of the invention is to provide a tube comprising not just one distribution opening of given cross-section, but a plurality of openings, the sum of the cross-sections of which is greater than or equal to that of the distribution opening of a tube with single distribution opening according to the prior art.

(8) In the figures, a jet pump 14 according to the invention comprises a body 16 equipped with a seamless, propulsion fluid supply tube 17 comprising a plurality of distribution openings 18 and 19, in this case two openings.

(9) The body 16 as a hollow rectilinear part, in this case rotationally symmetric, extending along its longitudinal axis AX, comprising at one of its ends, a so-called collector portion 21 defining an intake opening 22, and at its other end, a discharge opening 23 via which the mixture of the withdrawn fluid with the propulsion fluid is expelled.

(10) The collector 21 comprises a convergent duct 20 forming a restriction, in this case substantially conical, extending from the intake opening 22 to its reduced end 24, the diameter of which is significantly less than the diameter of the opening 22. The convergent duct 20 is extended at its end 24 by a cylindrical portion 26, this cylindrical portion in turn being extended by a flare 27 terminated by the discharge opening 23 of the pump.

(11) The diameter of the cylindrical portion 26, which corresponds to the diameter of the reduced end 24 of the duct 20, is significantly less than the diameters of the intake and discharge openings, which are substantially identical. In the examples of FIGS. 5 and 6, the diameter of the cylindrical portion has a value half that of the diameter of the openings 22 and 23.

(12) The tube 17 which provides the supply of propulsion fluid is a seamless duct, in this case rectilinear, extending along an axis AR. This tube 17 extends between a flared outer end 28 having a circular opening 31 for connection to a propulsion fluid supply pipe, and a terminal inner end 32. It equips the duct 20 of the collector 21, the wall of which it passes through, being positioned so that its axis AR extends radially with respect to the central axis AX of the duct 20. This tube 17 thus comprises an outer portion 17a situated outside the duct 20 and an inner portion 17b situated in this duct, having its end 32 against the inner face of the latter.

(13) The inner end 32 has a bevelled shape shown in FIG. 4, with a bevel angle corresponding to the half-angle at the apex of the cone defined by the conical wall forming the collector 21. The inner end 32 is thus in abutting contact on the inner face of the duct 20 when the assembly is mounted to form the collector 21.

(14) As can be seen in FIG. 4, the distribution openings 18 and 19 of this tube 17 each pass through the wall of the tube, each having an approximately circular contour. These two openings 18 and 19 have approximately the same cross-section, and they are orientated towards the discharge opening 23 of the pump when the tube is mounted. These openings are adjacent to one another along the axis AR of the tube, being situated on either side of the longitudinal axis AX of the duct 20 when the tube same.

(15) The inner portion 17b of the tube 17 has, when viewed in cross-section with respect to the axis AR, a tapered shape approximating a drop of water, defining a tapered leading edge 33 orientated towards the intake opening 22, the openings 18 and 19 being situated opposite leading edge 33 with respect to the axis AR.

(16) Due to this tapered cross-section, the tube 17 minimises the pressure losses introduced by its presence in the duct 20, with respect to the withdrawn fluid which passes through this duct of the collector, and which can then pass around it without significant disruption to its flow.

(17) In a general manner, the choice of the tube having a straight inner portion and having a tapered cross-section provided with a plurality of distribution openings, makes it possible to obtain a collector of smaller dimensions in comparison with the collectors of the prior art that comprise a seamed tube terminated by a single distribution open that determines the diameter of the entirety of the pump. In other words, for a given cross-section of distribution opening, the choice of a straight tube having a plurality of openings for which the sum of the cross-sections is greater than or equal to the given distribution opening cross-section, makes it possible to dimension a more compact jet pump in terms of both diameter and length, and similarly more lightweight.