US3054256A

US3054256A - Adjustable discharge nozzle and jet engine provided with such a nozzle

Info

Publication number: US3054256A
Application number: US852070A
Authority: US
Inventors: Minos Jean-Marie
Original assignee: SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1958-11-12
Filing date: 1959-11-10
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18
Also published as: GB876583A; DE1129775B; FR1215236A

Description

p 1962 JEAN-'MARIE MINOS 3,054,256

ADJUSTABLE DISCHARGE NOZZLE AND JET ENGINE PROVIDED WITH sucn A NOZZLE I Filed NOV. 10, 1959 3 Sheets-Sheet 1 Fig.2

I u VIA/70A Sept. 18, 1962 JEAN-MARIE MINOS 3,054,256

ADJUSTABLE DISCHARGE NOZZLE AND JET ENGINE PROVIDED WITH SUCH A NOZZLE Filed Nov. 10, 1959 3 Sheets-Sheet 2 Vfddlit/1 1 w- 5 Sept. 18, 1962 JEAN-MARIE MINOS 3,054,256

ADJUSTABLE DISCHARGE NOZZLE AND JET ENGINE PROVIDED WITH SUCH A NOZZLE Filed Nov. 10, 1959 6 hee she s Fig. 9

ENTOK United States Patent Oflice Patented Sept. 18, 1962 The present invention relates to a discharge nozzle whose cross-section is adjustable in dependence on the working state and whose shape can also be modified in order to allow it to change from a convergent shape suitable for subsonic flows to a convergent-divergent shape adapted to supersonic flows, and vice versa. This discharge nozzle is so arranged as to permit variations of the cross-sections at the throat and at the outlet and also variations in the relationship between these crosssections.

According to the present invention, the discharge nozzle comprises two groups of mobile wall elements: an upstream group forming a divergent portion and a downstream group in prolongation of the said convergent portion or forming a divergent portion, the wall elements of the downstream group being capable of a combined translational and rotational movement in longitudinal planes by means of an appropriate guiding device, for example under the action of a control device provided specially for this downstream group. The elements of the upstream group can be operated by the movement of the downstream group of elements or, preferably, can be given their own control device independent of that of the elements of the downstream group.

The clearance which can exist between the two groups of elements in certain positions thereof is advantageously utilised for introducing ambient air to the throat by an ejector effect due to the flow of gases through the discharge nozzle.

The description which now follows with reference to the accompanying drawings, given by way of non-limitative example, will make it understood how the invention can be carried into effect, the features brought out both from the text and from the drawings forming, of course, part of the said invention.

FIGURES 1 to 4 are very disgrammatic views in longitudinal section of a discharge nozzle which is assumed to be of rectangular cross-section in order to keep the drawings simple, showing four diflerent shapes for the said nozzle.

FIGURES 5 and 6 are similar sectional views in rather more detail, showing the control and guiding means for the mobile wall elements.

FIGURE 7 is a diagrammatic cross-section showing the upstream shutters of a nozzle which is a body of revolution, in their maximum and minimum open positions, taken on the lines VlIa--VIIa and VIIb-VIIb of FIG- URES 5 and '6.

FIGURE 8 is similar to the preceding figure but relates to the downstream elements, taken on the lines VIIIa-VIIIa and VIIIbVIIIb of FIGURES 5 and 6-.

FIGURES 9, 10 and 11 illustrate diagrammatically three discharge nozzle shapes whose upstream and downstream mobile wall element groups have separate controls.

In FIGURES 1 to 4, 1 is the outlet duct for the hot gases which is arranged downstream of the turbine in the case of a turbo-jet engine or downstream of the combustion chamber in the case of a ram-jet engine. This duct terminates in the adjustable discharge nozzle which, according to the invention, is constituted by two groups of mobile wall elements: a group of upstream shutters 2 pivotally mounted at 3 on the fixed part of the duct 1 and forming the convergent portion, a group of downstream elements 4 capable of combined translational and rotational movement and adapted either to form a convergent portion in prolongation of the first or to form a divergent portion downstream of the convergent portion, or of being retracted laterally.

In the position shown in FIGURE 1, the mobile elements 4 prolong the convergent portion started by the shutters 2. The discharge nozzle has a shape adapted for subsonic working states, corresponding for example to the ignition of a turbo-jet engine in the dry condition, i.e. without using the post-combustion device.

FIGURE 2 shows another shape which is also suitable for an engine operating in the dry condition and wherein the upstream shutters 2 form a markedly convergent nozzle whereas the rear mobile elements 4 are withdrawn laterally to the maximum extent. possible, more particularly, for air to be sucked in by an ejector eflect through the clearance 5 between the upstream elements 2 and the downstream elements 4, thus creating a circulation of air between the gaseous jet issuing from the convergent portion 2 and the wall of the divergent portion 4.

The shape of the discharge nozzle illustrated in FIG- URE 3 corresponds to working states in the vicinity of the supersonic threshold and is applicable to discharge nozzles of ram-jet engines or turbo-jet engines when operating with post-combustion. The elements 4 are parallel to the axis or slightly divergent.

Finally, in the case of FIGURE 4, the discharge nozzle of the ram-jet or turbo-jet engine operating with postcombustion is adapted to supersonic working states and has a markedly convergent-divergent shape.

FIGURES 5 and 6 show a mechanism for controlling the mobile wall elements of the discharge nozzle. The

rear elements 4- are guided by two

slideways

6 and 7 arranged in a plate 8 fast with the streamlined portion 9 and wherein are

displaceable pins

10 and 11 associated with the elements 4, which are also pivotally connected at 12 to a rod 13 connected to the rod 14 of a hydraulic jack 15. The

slideways

6 and 7 are given an appropriate inclination in accordance with the conditions of use and the cross-sections envisaged for the outflow of the gases.

It is possible to provide a plurality of jacks 14 distributed about the duct 1, simultaneous and synchronous control being ensured by a ring 16 connecting the rods 14 of the jacks.

The displacement of this ring 16 from the left (FIG- URE 5) to the right (FIGURE 6) under the action of the jacks will cause, by virtue of the inclination of the cam-action slideways 67, a combined translational and rotational movement of the elements 4 in longitudinal planes, as will be clearly seen from the drawings.

In this form of embodiment, the upstream shutters 2 are controlled by the downstream elements 4 against which they bear under the influence of the pressure exerted by the jet. However, in order to prevent ony fluttering, it is possible to apply these upstream shutters strongly against the elements 4 by means of a spring or a return jack. Thus the translational and rotational movements of the elements 4 from the position shown in FIGURE 5 to that shown in FIGURE 6 have the result, owing to the action of the front end of the elements 4 on the outer face of the shutters 2, of deflecting the latter in the sense of a markedly convergent setting, as shown in FIGURE 6.

In the case of a nozzle which is body of revolution, in accordance with current practice there will be used overlapping elements which can slide on one another during the course of their radial movement in order to This shape makes it' retain a more or less circular and continuous shape, and to ensure fluid-tightness at the sides of the jet. These overlapping elements are shown diagrammatically in FIG-

URES

7 and 8 in the positions corresponding to maximum and minimum cross-sections in each case.

The control device used in the form of embodiment of FIGURES and 6, of course, permits only the two shapes shown with reference to FIGURES 3 and 4 and corresponding to operation with post-combustion.

If it is desired to be able to have other shapes also, such as those in FIGURES 1 and 2, it will be necessary to make the upstream shutters 2 independent of the mobile downstream elements 4 and to provide a separate control for each group.

FIGURES 9, 10 and 11 show an arrangement of this kind: the upstream shutters 2 are associated with a group of jacks 17 which are independent of the jacks 15 to which the downstream elements 4 are connected, the guiding means for these latter elements being shown diagrammatically at 18.

It is possible here also to provide a connection in the form of a ring similar to 16 for the simultaneous and synchronised control of the elements of each group. But it would also be possible to control each element or some of them separately in order to give them asymmetrical positions causing deflection of the jet. In certain cases, the supply of working medium to the jacks 17 controlling the upstream shutters 2 can be cut off and only the jacks 15 controlling the downstream elements 4 are used. This again provides an arrangement similar to FIGURES 5 and 6 but with the difference that the jacks 17 act as dash-pots.

The upstream shutters 2 can be hollow and cooled by circulation of air escaping towards the rear. Two methods of cooling can be considered: either by means of air taken from the compressor or more simply by aspiration of air by means of the ejector effect exerted by the jet.

It will be apparent that modifications can be made to the forms of embodiment which have just been described, more particularly by the substitution of equivalent technical means, without, however, departing from the scope of the present invention.

What I claim is:

1. A discharge nozzle mounted in a fairing, having an adjustable and substantially circular section and comprising two groups of mobile wall elements and associated control means including longitudinal jacks, a downstream group pivoted about their mid-point on a pin slidable in a longitudinal slideway fixed to the fairing, and also pivoted about their front end on a rod linking the longitudinal jack to a slideway situated in a radial plane and in an oblique direction relative to the longitudinal axis, an upstream group of elements respectively pivotally supported at their upstream ends for movement toward and away from said longitudinal axis, said elements of the upstream group having free downstream ends disposed inward of and longitudinally overlapping the elements of the downstream group, means independent of said up stream group for longitudinally adjusting and for positively determining the angular positions of said elements of the downstream group about their midpoints, and means independent of said downstream group for limiting the movement of said free downstream ends away from said longitudinal axis.

2. Discharge nozzle according to claim 1 wherein the control means of the upstream group compirse elastic means urging them to bear on the front end of the downstream group.

3. Discharge nozzle according to claim 1 wherein the elements of the upstream group are subjected to the action of independent control means, whereby a clearance can be provided between the said two groups for the introduction of ambient air by providing an ejector effect.

References Cited in the file of this patent UNITED STATES PATENTS 2,597,253 Melchior May 10, 1952 2,625,008 Crook Jan. 13, 1953 2,858,668 Kelley Nov. 4, 1958 2,910,829 Meyer Nov. 3, 1959 2,931,169 Glenn Apr. 5, 1960 2,932,163 Hyde Apr. 12, 1960 2,939,274 Olson June 7, 1960