US2975593A

US2975593A - Jet propulsion units

Info

Publication number: US2975593A
Application number: US658161A
Authority: US
Inventors: Bauger Louis Jules; Barthlme Anton
Original assignee: SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1956-05-11
Filing date: 1957-05-09
Publication date: 1961-03-21
Anticipated expiration: 1978-03-21

Description

March 21, 1961 L. J. BAUGER ETAL 2,975,593

I JET PROPULSION UNITS Filed May 9, 1957 s sneets-shee 1 lNVE-NTORS' Au-rou BARTHLME Ldula \TuLas .BAUBER ATTORNEYS March 21, 1961 L. J. BAUGER ETAL 2,975,593

JET PROPULSION UNITS Filed May 9, 1957 3 SheeIS*-Sh69t 2 INVENTORS ANTON IBARTHLME Lows TuLEs .BAU6ER 7 ATTORNEYS J. BAUGER EI'AL 2,975,593

JET PROPULSION UNITS 3 Sheets-Sheet 3 7 2 a a H K i ixIMWMWI W 4 a INVE NTOR s. ANTON .BARTHLME LOUIS J'uLEs BAuaER ATTORNEYS March 21, 1961 Filed May 9, 1957 United States Patent JET PROPULSION UNITS Louis Jples Banger, Vanves, France, and Anton Barthlme, Munich, Germany, assignors to Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France, a French company Filed May 9, 1957, Ser. No. 658,161 Claims priority, application France May 11, 1956 1 Claim. (Cl. 60-4554 It has already been proposed to provide jet propulsion units with jet deflecting devices comprising, for example a divergent curved guide surface disposed behind the edge proper of the outlet orifice of the propulsion unit, this surface being followed in some cases by a grate of semicircular deflector blades. The deflection is initiated by solid or fluid obstacles disposed in the flow. On the other hand, it has also been proposed to adjust the cross-sectional outlet area of the jet by means of movable flaps.

The presence of solid deflecting obstacles in the flow, or at least the presence of the support of such obstacles, results in losses of thrust in the direct flow of the jet even when these obstacles are retracted. The present invention permits of obviating this disadvantage, and concerns a jet propulsion unit, in which the outlet orifice of the nozzle is provided with movable flaps of spherical or other form adapted to the form of the nozzle for the adjustment of the cross-sectional area afforded to the jet, as also with a deflecting device comprising a curved guide surface (advantageously followed by a grate of deflector blades) which is separated by a clearance from the edge proper of the outlet orifice, the flaps being so arranged as to be retractable into the said clearance and being adapted to take up a position one against the other in a diametral region of the nozzle in order to generate an obstacle to the axial flow of the jet and thus to deflect the latter towards the guide surface.

However, such a device would only permit relatively small variations of the cross-sectional outlet area of the nozzle, since the surface of the flaps is limited to that which is necessary for producing the deflection of the jet. The cross-sectional variation produced by these flaps would then be insufficient, especially in the case of turbojet units having after-combustion and comprising a jet deflector associated with the nozzle.

In such engines, the variation of the cross-section of the jet is much greater than that which is necessary in engines having no after-combustion. The simple flap then becomes insuflicient to ensure the necessary cross-sectional variation between the takeoff without after-combustion and take-off with after-combustion and a fortiori insufficient to ensure the cross-sectional variation necessitated by after-combustion at altitude.

Therefore, in accordance with an advantageous feature of the invention, double or multiple spherical flaps are provided which are adapted to be retracted one into the other or to be controlled independently.

The description given in the following with reference to the accompanying drawings, which are given by way of non-limitative example, will enable the manner in which the invention can be carried into practice to be readily understood, the features appearing both from the drawings and from the text naturally forming part of the said invention.

Figure l is an elevational view, partly in section, of the rear part of a jet propulsion unit having after-combustion and comprising a jet deflector according to the in- Figure 3 is a section along the line III-.-IlI of Fig. 2;

Fig. 4 is an axial section through'an improved constructional form permitting notably retraction of the guide surface and of the blade grate, the device being illustrated in the position for deflectionof the jet; and

Figure 5 shows a modified form with a fixed blade lattice and a movable outer fairing.

There will be seen in Figure 1 a jet propulsion nozzle 1, the outlet orifice of which, designated by its edge 1a, is surrounded by a circular ring 2 having an'outwardly flared curved surface 2a a little on the downstream side of the edge 1a. The ring 2 is followed by a series of circular deflector blades 3. The assembly comprising the ring 2 and the deflector blades 3 is fixed to the wall of the nozzle by tie rods 4. A clearance 5 is left between the edge 1a and the ring 2 to create by an aspiration effect under the action of the jet an intake of external air 'which prevents the jet from adhering to the surface 2a when the jet is to be axially ejected, outside the deflection periods. In the position illustrated in Figure 1, two pairs of

spherical flaps

6a, 6b, 6'a and 6b having different radii in each pair and pivotally mounted on a pin 7 situated in the diametral plane of the nozzle perpendicular to the plane of the figure, are disposed between the ring 2 and the terminal portion of the nozzle. The radii of the said flaps are such that the flaps 6'a and 6b can slide with slight clearance on the

flaps

6a and 6b. These flaps therefore enter the clearance 5.

When these flaps are in the fully open position and completely retracted into the clearance 5, their extreme downstream edges are placed at a distance greater than the diameter of the outlet edge 1a, so that the jet can flow axially from the nozzle as if there were no flaps and no deflector members.

In the position illustrated in Figure 1, the flaps have been moved towards one another in such manner that they intercept certain marginal streams. Thus, as a result of a shearing effect on these flaps, there is a reduction in the total cross-section of the jet, as indicated by the arrows representing the streams of the jet. In the position of Figure 2, the

flaps

6a and 6b are closed, that is to say, applied one against the other in the central zone of the jet, while the flaps 6'11 and 6b are retracted, leaving the nozzle fully open. The

flaps

6a and 6b divide the jet into two parts, which are taken up by the blade grate 3 and deflected as indicated by the arrows. The retracted

flaps

6a and 6b uncover the guide surface 2a, to which the deflected jet can adhere.

Figure 3 illustrates one constructional form for the control of the flaps. Each of the flaps is controlled by a jack such as 8a, 8b, the rod of which is linked by a connecting rod 9a, 9b to a lever 10a, 10b fast with the pivot 11a, 11b connected to the corresponding flap.

If desired, only the appropriate jack or jacks for actuating a single flap or a single pair of flaps may be fed whereby an asymmetrical deflection is obtained. If, for example, starting from the position in which all the flaps are retracted into the clearance '5, only the jacks of the pair of

flaps

6a, 6a are fed in order to bring these flaps into the position illustrated in Figure 1, the jet is deflected downwards with reference to Figure 1, this deflecting being accentuated by the blade grate. A variation of the direction of the thrust is thus obtained which permits of exerting a steering couple on the aircraft.

It is always advantageous in the absence of deflection to retract the members provided for this purpose on the upstream side of the outlet orifice. For this purpose, in

Patented Mar. 21, 1961 the constructional form illustrated in Figure 4, the guide ring 2 is divided into two parts, one part 2a being fixed and the other 2b being movable and connected to the blades 3.v The assembly comprising the ring 2]) and the blades 3 can slide in an upstream direction parallel to the axis of the nozzle so as to enter the fairing 15 under the tractive' action of jacks 12 connected to the ring 2b by tie rods 13 guided by rollers 14. In the upper half of Figure 4, the device is illustrated in the position for the axial ejection of the jet, the lower half of the figure illustrating the deflecting position.

In the constructional form illustrated in Figure 5, it is the fairing 15 which is movable and which moves towards the rear so as to cover, as indicated in chain-lines, the deflecting members, which are fixed, when the jet is to flow axially.

It will be obvious that modifications may be made to the constructional forms hereinbefore described, notably by substitution of equivalent technical means, without departing from the scope of the present invention.

What is claimed is:

The combination, with a jet propulsion nozzle ending with a circular outlet orifice for the discharge of a jet, of an outwardly curved convex annular surface having a minimum diameter greater than the diameter of said cir- 4 cular orifice, said surface extending around said orifice in radially spaced relation therewith to provide an annular gap around the periphery of said orifice and further extending axially downstream of said orifice, said gap facing substantially in an upstream-downstream direction and being open at both ends, and pivotal flaps mounted on said nozzle and movable through said. gap to a retracted position wherein they lie outside the nozzle out of contact with the jet issuing from said orifice and an operative position wherein they lie across part of the path of the jet to deflect it laterally whereby a portion of the jet adheres to said convex annular surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,551,372 Haltenberger May 1, 1951 2,735,264 Jewett Feb. 21, 1956 2,797,548 Marchal et al July 2, 1957 FOREIGN PATENTS 1,060,291 France Nov. 18, 1953 V 1,090,067 France Oct. 13, 1954 OTHER REFERENCES NACA Technical Note, 3664, February 1956.