GB2131883A

GB2131883A - Thrust nozzle arrangement

Info

Publication number: GB2131883A
Application number: GB8332980A
Authority: GB
Inventors: Alfred Weiss
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: Airbus Defence and Space GmbH
Priority date: 1982-12-16
Filing date: 1983-12-09
Publication date: 1984-06-27
Also published as: FR2538035B1; FR2538035A1; GB8332980D0; DE3246540A1; GB2131883B

Abstract

An arrangement for adjusting the thrust nozzle cross-section of reaction engines for flying bodies, particularly for reducing the large launching nozzle cross-section into a smaller cross- section for cruising operation, comprises two nozzles 1, 2 each having a large cross-section and two nozzles 3, 4 each having a small cross-section. All the nozzles are arranged in a rotatable disc 5 so that they can be brought alternately into the path of the combustion gases by an adjusting piston 17 powered by gases from a propellant charge. <IMAGE>

Description

SPECIFICATION Thrust nozzle arrangement This invention relates to a thrust nozzle arranged mentfor adjusting the thrust nozzle cross-section of reaction enginesforflying bodies, more particularly for lessening the thrust nozzle cross-section which is fairly large during launching operation into a smaller thrust nozzle cross-section for cruising operation.

Rocketenginesinstalledinflying bodiesfortheir propulsion often serve both as launching and cruising engines with a thrust nozzle which is not adjustable in its geometry. In this respect, with regard to the mass throughput ofthrust gases which is considerably greater during the launching phase in contrast to the cruising flight, certain disadvantages arise insofar as the constant nozzle geometry can represent only a compromise between the design for the launching phase and the design forthe cruising flight, whereby for both phases, or at least four one phase, unavoidable thrust losses or losses of efficiency have to be tolerated. Thrust ratios between the launching and cruising operation of a maximum of 4:1 can be achieved with this arrangement.However, often greaterthrust ratios between the two aforementioned operating ranges are required.

In order to avoid this drawback, it is known, as disclosed for example by German Offenlegungsschrift No. 21 30 422, to design the thrust nozzle so as to be variable in its geometry. In this respect, during the launching phase a larger nozzle neck cross-section is worked with, whilst upon the cruising flightwith the aid of an axially insertable auxiliary nozzle a correspondingly reduced nozzle neck cross-section is run with. On the one hand the functional advantage achieved with this combined nozzle construction must however on the other hand be paid for, besides a considerable construction cost and construction weight, with flow losses through the reduction nozzle which is present in the flow and which is over and above that exposed to high thermal stresses, and with a lengthened thrust nozzletype of construction.

Thetaskoftheinvention istoavoidthedisadvan- tages ofthe known versions and to provide a thrust nozzle arrangement having adjusting properties which entails a short type of construction and in which the thrust nozzles come subsequently into use or respectivelythecruising nozzles remain thermally protected during the launching phase, so that an exact functioning ofthe switch-over and a satisfactory working during the second use or action phase or cruising phase respectively is guaranteed.

This problem is solved in that the present invention provides a thrust nozzle arrangement for adjusting the thrust nozzle cross-section of reaction engines for flying bodies, more pa rticularly for lessening the thrust nozzle cross-section, which is fairly large during the launching operation, into a smallerthrust nozzle cross-section for cruising operation, characterised by an even number of, more particularlytoo, th rust nozzles which are in each case larger in cross-section and an even number of, also more particularlytwo, thrust nozzles which are in each case smaller in cross-section,which lie one behind the other at the same separation spacing in the peripheral or circumferential direction, alternately in each case a smaller thrust nozzle and a larger thrust nozzle, in which respect either the group having the smallerthrust nozzles orthe group having the largerthrust nozzles is switched orfreed respectivelyforgas passage.

In one aspectofthe invention,thethrust nozzle arrangement has, upon use of convergent-divergent supersonic thrust nozzles, a rotary switching or indexing disc our plate which is concentric with regard to the individual thrust nozzles and in which the smaller thrust nozzles are wholly provided and the thrust nozzle neck regions ofthe largerthrust nozzles are provided.Furthermore, the proposed thrust nozzle arrangement has, inthis respect,a housing-fastfront thrust nozzletransversewall or partition or diaphragm or bulkhead having front convergent thrust nozzle regions and a housing4ast rearthrust nozzle trans- verse wall having rear divergent th rust nozzle regions forthe largerthrust nozzles, in which respect in the "largerthrust nozzles" switching position the thrust nozzle neck regions of the switching disc correspond withthefrontconvergentthrustnozzle regions and the rear divergent thrust nozzle regions, whilst in so doing the smallerthrust nozzles are blocked in the flow-through direction by the front housing transverse wall, and in the "smaller thrust nozzles" switching position, which is achieved by swinging the switching discthrough 90 inthe circumferential direction, the smallerthrust nozzles provided in the switching disc correspond with the front convergent thrust nozzle regions and the rear divergentthrust nozzle regions, whilst in so doing the largerthrust nozzles are blocked in theflow-through direction by means of the switching disc.

Furthermore, thethrust nozzle arrangement in accordance with the invention is equipped with an adjusting device which consists of a ring or annular cylinder which is provided in the switching disc and has a length which corresponds to the switch-over path ofthe switching disc, and of an immovablyarranged adjusting piston which is disposed in the ring cylinder.

The thrust nozzle arrangement in accordance with the invention, which is distinguished byashorttypeof construction, makes possible nozzle-wise an exactlyfunctioning switch-over and adaptation to both operating phases.

The invention will be described further, byway of example, with reference to the accompanying draw inns in which: Figs. 1 and 2 illustrate an arrangement of convergent-divergent supersonicthrust nozzles having two diametrically-opposedly arranged largerthrust nozzles and having two diametrically oppositely arranged smallerthrust nozzles, in which respect both thrust nozzle groups are offset to one another by 90" in the circumferential direction and in this respect Fig. lisa longitudinal section through the two largerthrust nozzles and Fig. 2 is a longitudinal section through the two smallerthrust nozzles; Fig. 3 is a longitudinal section along the linelll-lll in accordance with Fig. 1; and Fig. 4 is a section, angled through 90 , along the line IV-IV in accordance with Fig. 3.

As emerges from the drawings, the preferred thrust nozzle arrangement of the invention hastwothrust nozzle groups, one thrust nozzle group having larger thrust nozzles 1 and 2 which lie in one longitudinal plane A, and a thrust nozzle group having smaller thrust nozzles 3 and 4which are arranged in another longitudinal plane B which extends at right angles to the first-mentioned longitudinal plane A. The main component parts of the thrust nozzle arrangement are a rotatably-mou nted switching disc5, a front housing fastthrust nozzle transverse wall 6 having a heat protection covering 6a and a rear housing-fast thrust nozzle transverse wall 7.The two smallerthrust nozzles 3 and 4 as well as in each case the centrallysituated thrust nozzle neck regions 8 and 9 ofthe two largerthrust nozzles 1 and 2 are provided in the switching disc 5. Thefrontthrust nozzle transverse wall 6 having the heat protective covering 6b has two front convergent thrust nozzle regions 10 and 11 which correspondwith the thrust nozzle neck regions 8 and 9. Positioned on the rearthrust nozzle transverse wall 7 are divergent thrust nozzle regions 12 and 13 which also correspond with the th rust nozzle neck regions 8 and 9.

In the case of the "larger th rust nozzles" position shown in Fig. 1, the one convergent thrust nozzle region 10, the one thrust nozzle neck region 8 and the one divergentthrust nozzle region 1 2form one larger thrust nozzle 1 and the otherconvergentthrust nozzle region 11 ,the otherthrust nozzle neck region 9 and the other divergentth rust nozzle region 13form a second largerthrust nozzle 2, through which both the nozzle 1 and the nozzle 2 during the launching phase flows propellant gases G generated in a combustion cham bey 14.

If switching discS is swung through 90 in the direction ofthe arrowX at the end ofthe launching phase of the flying body, then the situation shown in Fig. 2 presents itself. The gas passage is then effected through the smallerthrust nozzles 3 and 4, which are in alignment with the front convergent thrust nozzle regions 10 and 11 and with the rear divergent th rust nozzle regions 12 and 13.

This change-over ofthe switching disc5 is carried out by a thrust nozzle adjusting device 15 which consists of a ring cylinder 16 provided in the switching disc5and having a length Lwhich corresponds to the switch-over path of 90 ofthe switching disc 5, and of an adjusting piston 17 which is associated in a housing-fast manner, in other words is immovable, and which is present in the ring cylinder 16. The switching disc5 is driven bya pyrotechnical gas generating mechanism which has a fixed or solid propelling charge 18 which is ignited to switch over the switching disc 5. By burn-off of the propellant charge 18, pressure gas is generated, which flows through a bore 19 in the adjusting piston 17 into the ring cylinder 16 and thereby sets the switching discS rotating.

Claims

1. Athrust nozzle arrangementforadjusting the thrust nozzle cross-section of reaction engines for flying bodies, more particularlyfor lessening the thrust nozzle cross-section, which is fairly large during the launching operation, into a smallerthrust nozzle cross-section for cruising operation, characterised by an even number of, more particularlytwo, thrust nozzles which are in each case larger in cross-section and an even number of, also more particularlytwo, thrust nozzles which are in each case smailer in cross-section, which lie one behind the other at the same separation spacing in the peripheral or circum- ferential direction, alternately in each case a smaller thrust nozzle and a largerthrust nozzle, in which respect either the group having the smallerthrust nozzles orthe group having the largerthrust nozzles is switched orfreed respectively for gas passage.

2. Athrust nozzle arrangement as claimed in claim 1 having convergent-divergent supersonic thrust nozzles, characterised bya rotary switching or indexing disc which is arranged concentrically with regard to the individual thrust nozzles and in which the smaller thrust nozzles are fully provided and the thrust nozzle neck regions of the largerthrust nozzles are provided, and furthermore bya housing-fastfrontthrustnonle transverse wall, partition, bulkhead or diaphragm having front convergentthrust nozzle regions as well as by a housing4ast rearthrust nozzle transverse wall having rear divergent th rust nozzle regions forthe largerthrust nozzles, in which respect in the "larger thrust nozzles" switching position the thrust nozzle neck regions of the switching disc correspond with the front convergent thrust nozzle regions and the rear divergentthrust nozzle regions, whilst in so doing the smaller thrust nozzles are clossed off in the flowthrough direction bythe front housing transverse wall, and in the "smaller thrust nozzles" switching position, which is achieved by swinging the switching disc through 90 in the circumferential direction or arrow direction (X) respectively, the smallerthrust nozzles provided in the switching disc correspond with the front convergentthrust nozzle regions and the reardivergentthrust nozzle regions, whilst in so doing the largerthrust nozzles are blocked in the flow-through direction by means of the switching disc.

3. Athrust nozzle arrangement as claimed in claim 1 and 2, characterised by a thrust nozzle adjusting device which is operated with pressure gas and which consists of a ring or annular cylinderwhich is provided in the switching disc and which has a length which corresponds to the change-over or switch-over path of the switching disc, and ofanimmovably-arranged adjusting piston which is present in the ring cylinder.

4. Athrust nozzle arrangement as claimed in claim 3, characterized in that connected to the ring cylinder is a pyrotechnical gas generation mechanism in which there is installed a solid (orfixed) propelling charge which is to be ignited for the switch-over ofthe switching disc and the propellant gases of which flow through a bore in the adjusting piston into the ring cylinder.

5. Athrust nozzle arrangementas claimed in claim 1 and 2, characterised in that the front thrust nozzle transverse wall is provided, on its front end face, with a heat protective covering orfairing.

6. Atrust nozzle arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.