US2780056A

US2780056A - Jet-nozzle arrangement with outletarea varying means

Info

Publication number: US2780056A
Application number: US437217A
Authority: US
Inventors: Colley Rowan Herbert
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1954-03-26
Filing date: 1954-06-16
Publication date: 1957-02-05
Anticipated expiration: 1974-02-05
Also published as: GB782494A

Description

R. H. COLLEY I 2,780,056

Feb. 5, 1957 JET-NOZZLE ARRANGEMENT WITH OUTLET-AREA IARYING MEANS Filed June 16, 1954 4 Sheets-Sheet l A n l I! II Feb. 5, 1957 R. H. COLLEY 2,780,056

JET-NOZZLE ARRANGEMENT WITH OUTLET-AREA VARYING MEANS Filed June 16, 1954 4 Sheets-Sheet 2 Feb, 5, 195? R. 1-1. COLLEY JET-NOZZLE ARRANGEMENT WITH O TLET-AREA VARYING MEANS Filed June 16, 1954 4 SheetsSheet 5 w mm w 5 & RAIN: O

Feb. 5, 1957 1 R. H. COLLEY 2,780,056

JET-NOZZLE ARRANGEMENT WITH OUTLET-AREA VARYING MEANS Filed June 16, 1954 4 SheetsSheet 4 United States Patent JET-NOZZLE ARRANGEMENT WITH OUTLET- AREA VARYIN G MEANS Rowan Herbert Colley, Derby, England, assignor to Rolls- Royce Limited, Derby, England, a British company Application June 16, 1954, Serial No. 437,217 Claims priority, application Great Britain March 26, 1954 7 Claims. (Cl. 60-35.6)

This invention comprises improvements in or relating to jet-nozzle arrangements such as are employed in connection with gas-turbine engines for reaction-propulsion purposes.

It is well-known to employ variable-area jet nozzles with gas-turbine engines, so that, for instance, when the engine is fitted with afterburner equipment the effective area of the jet nozzle can be increased thereby to avoid overheating the turbine of the engine when the afterburner equipment is operating.

In British patent application No. 16,933/53, Rolls- Royce Limited, there is described an improved variablearea jet nozzle which comprises a number of pivoted nozzle elements by means of which the outlet orifice area is varied, and motor means by which the pivoted nozzle elements are moved from one position to another, which motor means is mounted on the pivoted nozzle elements themselves. In the preferred arrangement described in the prior application, the motor means are in the form of rams having circumferentially-directed lines of action, one part of the ram being attached to one nozzle element and a second and relatively movable part of the ram being attached to an adjacent nozzle element. With such an arrangement the nozzle elements may be constrained to rock outwardly and inwardly by telescoping the rams. The nozzle elements themselves in this arrangement are elongated axially of the jet nozzle and are pivoted for rocking movement adjacent their upstream ends, and the rams are described as hydraulic rams whereof the cylinders are attached in pairs to alternate nozzle elements and the pistons are connected in pairs with the remaining nozzle element through pivoted links. In the preferred arrangement, moreover, the number of nozzle elements is relatively large, there being, for instance 16 such nozzle elements.

The present invention comprises improvements in or.

modifications of the invention set forth in mentioned prior application.

According to the present invention, a jet nozzle comprises a plurality of nozzle elements which are assembled in circumferential juxtaposition, extend axially and are pivoted at their upstream edges, and operating means to cause pivoting of the nozzle elements to vary the nozzle area comprising a plurality of screw jacks arranged around the nozzle elements to form a substantially closed polygon, each screw jack having a screw element mounted on a nozzle element and held against circumferential displacement with respect to it, and a co-operating nut element mounted on an adjacent nozzle element and held against circumferential displacement with respect to it, and power input means to effect relative rotation of the screw and nut elements. It will be clear that on relative rotation of the screw-jack elements, the screw jacks will telescope and so cause rocking of the nozzle elements.

According to a preferred feature of the invention, each alternate nozzle element has mounted on it the screw elethe abovements of a pair of screw jacks which are arranged to extend in circumferentially opposite directions, and each of the remaining nozzle elements has mounted on it the nut elements of the pair of screw jacks which extend towards it from the nozzle elements at each side of it. With this arrangement it will be appreciated that the operatingmeans for rotating a screw jack element to cause telescoping of the screw jack will be associated with every alternate nozzle element, and the same power-input means may be employed to operate two jacks; for instance, if the nut elements are rotated then the power-input means for operating the screw jacks will be provided only in association with those nozzle elements carrying the pairs of nut elements.

According to another feature of this invention, the power-input means for operating the screw jacks may comprise a circular rack coaxial with and rotatable with respect to the nozzle, drive means to rotate the rack, pinions cooperating with the rack to be driven thereby, and axially-extending drive shafts connected to transmit a drive from the pinions, and gear mechanisms mounted on the nozzle elements and adapted to be driven by the drive shafts and to transmit a drive from the shafts to the rotatable elements of the screw jacks. In a construction as above described in which the screw elements of the jacks are mounted in pairs on alternate nozzle elements and the nut elements are mounted in pairs on the remaining nozzle elements, each gear mechanism may serve a pair of screw jacks, there being thus one shaft and gear mechanism for each pair of screw jacks. Conveniently, each gear mechanism comprises an input gear in the form of a bevel pinion and a pair of co-operating bevel gears carried by the rotatable elements of the associated pair of screw jacks. Conveniently, moreover, the shafts are connected with the pinions through universal couplings and are connected with the input gears of the gear mechanisms also through universal couplings, and a sliding spline connection is provided in the shafts to permit telescoping of the two ends of the shafts.

The invention may be employed with advantage with jet nozzle arrangements in which there are two sets of pivoted nozzle elements, the first set being pivoted at their upstream edges to stationary structure and the second set being pivoted by their upstream edges to the downstream edges of the nozzle elements of the first set, and in such jet nozzle arrangements each set of nozzle elements has an associated set of screw jacks. In this way a nozzle of the convergent/ divergent type may be provided in which the throat area and the outlet area are independently variable. In one construction according to this feature of the invention, the power-input means of each set of screw jacks comprises a corresponding circular rack co-axial with the nozzle and the two racks are arranged side by side to rotate about the jet pipe and are individually driven by drive means. In this arrangement the take-off pinions from the circular rack associated with the upstream set of nozzle elements are offset circumferentially from the take-off pinions associated with the downstream set of nozzle elements.

One construction of gas-turbine engine jet-pipe incorporating a variable-area nozzle with operating means in ing the adjustable parts in a second position of adjustment,

Figure 4 is a part section on the line 4-4 of Figure 2, the p ane of section of Figure 2 being indicated at 2'2,

Figure 5 is a part section on the line 5-5 of Figure 3, the plane of section of Figure 3 being indicated at 33,

Figures 6 and 7 show details of construction of a screw jack and its associated drive, and

Figure 8 is a detail of construction.

The nozzle is suitable, for instance, for use with a gasturbine engine which has an exhaust cone assembly at its outlet end, a first jet-pipe section of a ditfusing character wherein afterburner means are located connected to the exhaust cone assembly and, downstream of the first jet-pipe section, a second jet pipe section which is doublewalled, the space between the walls providing an annular cooling air passage through which in operation there is a flow of cooling air from adjacent the downstream end of the first jet-pipe section to adjacent the outlet end of a second jet-pipe section.

The downstream section is indicated at 121 and has walls 1241a, 12% spaced apart to define an air passage 1211c therebetween. The outlet end portion 121 of the second jet-pipe section 126? is' frusto-conical and convergent in the direction of gas flow through it.

Mounted on the outlet end of the second jet-pipe section 120 there is the variable-area jet nozzle by which the efiective outlet orifice area from the jet-pipe can be varied.

The jet nozzle comprises two sets of

nozzle elements

122, 123. The first set comprises eight nozzle elements 122 which are pivoted along their upstream edges to an,

axi'allyand circumferentially-extending peripheral flange 124 secured to the outer wall 1213a of the second jet-pipe section 124 and which project downstream from this flange 124. The second set also comprises eight nozzle elements 123, each of which is aligned with one of the nozzle elements 122 of the first set and is pivoted along its upstream edge to the downstream edge of that upstream nozzle element. Each nozzle element 123 of the sec-0nd set therefore forms an axial continuation beyond the end ofthe corresponding nozzle element 122 of the first set.

The axially-extending and circumterentially-adjacent edges of the

nozzle elements

122, 123 do not meet and there is provided for each set of nozzle elements a correspondingseries of

sealing flaps

125, 126, the sealing flaps 125 being overlapped circumferentially each by the adjacent edges of a pair of the nozzle elements 122 and the sealing flaps 126 being overlapped by the adjacent edges of a pair of the nozzle elements 123. Each of the sealing flaps 126 which are associated with the downstream nozzle elements 123 is pivoted along its upstream edge to the downstream edge of a sealing flap 12S associated with the upstream nozzle elements 122 and the latter sealing flaps 125 are'pivotally connected with the downstream edge of the jfrusto-conical portion 121 of the inner wall 12% of the second jet-pipe section 120;

The sealing flaps 125, 26 are formed from sheet metal and have two skins the outermost of which is corrugated," and eachsealing flap carries along each of its axially extending edges a sealing strip 127 which cooperates with the radially-inwardly-facing surface of the

nozzle element

122 or 123 overlapping it. it is arranged that in operation the sealing fiaps 125', 126 are maintain d in sealing contact withthe

nozzle elements

122, 123 by the pressure of the gases flowing to atmosphere through the jet nozzle.

Each of the nozzle elements 122 of the first set is formed from, sheet metal and has a plane inner skin and an axially corrugated outer skin 122a. The corrugated skins 122a have welded to them circumferentially-extending hinge pieces 128 of Z-section each of which has one flange in contact with the crests of the corrugations and a second flange spaced radially from them (see Figure 8). The corrugated skins 122a also have secured to them below the second flange of t-he Z-section strip 128 a braided metal rubbing pad 129.

The peripheral flange 124 on the outer wall 120a of the second jet-pipe section 12d carries at its downstream edge a series of hinge pieces 13% which co-operate with thehinge pieces 128 on the nozzle elements, and each of which has a flange to engage between the co-operating rubbing pad 129 and the second flange of the co-operating Z-sectiOn strip 128 and each of which is formed with a radially-inwardly-facing convex surface to cooperate with the rubbing pad 129.

A sealing element 129;: is also provided between the downstream edge of the inner jet-pipe skin 12% and the upstream edges of nozzle elements 122 and sealing. flaps 125.

The upstream nozzle elements 122 have secured to them at their downstream edges a pair of lugs 131 having. drillings parallel to the inner skin of the nozzle element to receive pivot pins 132 by which the downstream nozzle elements 123 areconnected to the upstream nozzle elements 122 and the downstream nozzle elements have corresponding lugs 133 with drillings adjacent their upstream edges.

The downstream nozzle elements 123 are also of sheetmetal construction having two skins, the inner of which is plane and the outer 12341 of which is axially corrugated.

The operating mechanism for efiecting co-ordinated pivoting of the sets of

nozze elements

122, 123 is as follows.

The peripheral flange 124 at the downstream end of the outer wall of the second jet-pipe section 12% is formed externally with a pair of axially-spaced races in which run

rollers

134, 135, and these rollers also run in races formed internally of a pair of

circular racks

136, 137 which have radially-outwardly-projecting teeth. The

racks

136, 137 are thus side by side and coaxial with the jet pipe and are capable of rotation about the jet pipe. An annular casing is secured externally of the jet pipe to enclose the racks.

Each of the

racks

136, 137 has associated with it four equally-

spaced pinions

138, 139 respectively, and the pinions 138 associated with the rack 136 are offset by 45- withrespect to the pinions 139 of the other rack 137 and thus the pinions 138 are circumferentially midway between the pinions 139. The

spindles

138a, 139a of the

pinions

138, 139 are journalled in blister housings 141 on the annular casing 140 each spindle having its axis parallel to the jet-pipe axis. One spindle 1381) and one spindle 13% of each set of the pinions is extended to outside its blister housing 141 to provide an input spindle to be driven by power means such as an electric motor 142 and thus one pinion of each set acts as a power input pinion to its associated rack. The

pinions

138, 139 have their spindles connected at their downstream ends through universal couplings 143 to axially-extending shafts 144' and 145respectively. The shafts 144 connected to the spindles of the pinions 138 associated with the upstream rack 136 extend to adjacent the downstream edge of the upstream set of nozzle elements 122, and the shafts 145 connected to the spindles of the pinions 139 associated with the downstream rack 137 extend to about midway along the downstream nozzle elements 123. Each of the

shafts

144, 145 has a spline connection 146 in its length to permit telescoping of the two ends of the shaft.

If desired, instead of employing one pinion of each ofthe sets of

pinions

138, 139 to drive the

respective racks

136, 137, separate drive pinions may be provided for this purpose.

At its downstream end, each of the eight

shafts

144, 145 is connected through a further universal coupling 147' to the spindle 148 of a bevel pinion 149 which is journalledin an associated gear box 150. The gear box 150 also contains two bevel gears 151 which mesh with the bevel pinion 149 and which have their axes contained in a plane at right angles to the axis of the bevel pinion 149 and inclined to one another at 135 and arranged to extend circumferentially in opposite directions. The gear boxes 150 are provided at their inner sides with radiallyprojecting lugs 152, and the lugs of the four gear boxes associated :with the shafts 144 are pivotally connected to the lugs 131 on the downstream edges of the upstream nozzleelements 122, and the.;lugs.15210n thejgear boxes 150. associated withtheshafts 145 arepivoted .to the nozzleelements 123. Since. there are eight nozzle elements 122 or 123m each set and since thefour

pinions

138, or 139 associated with each set' areequally. spaced around their co-operating rack 136 or137, only alternate nozzle elements of each set will have a gear box -150 pivotally mounted on it. Moreover since the pinions 138 are offset to be midway between the pinions 139, the upstream nozzleelements 122 which have gear boxes 150 pivotally mounted on them will be in line with those downstream nozzle elements 123 not having gear boxes .150

mounted on them.

Each of thebevel gears 151 has all-elongated hollow spindle154 (Figure 7)"which projects circumferentially from the gearbox 150 towards the nozzle element next adjacent that carrying, it and the hollow spindle 154 carries at its end remote from the'bevel gear '151 a nut element 155 of a r'e'circulating-ball-type screw jack. The

screw element 156 of the jack is aligned with the hollow spindle 154 of the bevel gear 151Ia nd, telescopes ,with respect to itpn rotation ofthe nut element 155. The screwelement 156 is secured to a bracket 157 which has radially-projecting lugs 158 through which it is,pivot:ed on said next adjacent nozzle element and the screw element ,156 of the next adjacent screw. jack extendscin curnferentially in the opposite direction from the same bracket 157 to co-operate with the nut element 155 driven through the next adjacent gear box. The two screw elements 156 mounted on each bracket 157 have their axes making 135 to one another.

Alternatively, the screw elements of the screw jacks may be attached to rotate with the bevel gears 151 and project within hollow spindles containing the nut elements (which may be of a recirculating ball type), the hollow spindles being secured to brackets such as the brackets 157.

The gear boxes 15% and brackets 157 also carry pairs of circumferentially-extending sleeves 15$ which surround the nut and screw

elements

155, 156 and which, when the screw jacks are operated, telescope one within the other.

From the foregoing description it will be appreciated that each set of

nozzle elements

122, 123 is independently operated in a co-ordinated manner by extension and retraction of the associated screw jacks. When the screw jacks are extended, the corresponding nozzle elements are caused to pivot outwardly to increase the effective area of the nozzle orifice as defined by the corresponding set of nozzle elements, and, when the screw jacks are retracted, the nozzle elements pivot inwardly.

It will be appreciated that by suitably controlling the operation of the two sets of screw jacks a convergent/divergent form of nozzle may be obtained.

It will also be appreciated that since the pinions 138 associated with the rack 136 are offset midway between the pinions 139 of the rack 137, the gear boxes 150 associated with the pinions 138 will be axially aligned with the screw-element-supporting brackets 157 associated with the pinions 139. This fact enables a simple form of stabilising arrangement to be employed. The stabilising means comprises eight circumferentially-spaced pairs of rods 16% pivoted at one end to the annular casing 149 one on each side of each of the

shafts

144, 145. The rods 1611 extend as far as and are pivoted to the gear boxes 15% or screw-elenient-supporting brackets 157 of the upstream set of nozzle elements 122 and further eight pairs of rods 151 extend from the same pivots on these gear boxes 15% and brackets 157 to be pivoted to the aligned brackets 157 and gear boxes 15% respectively of the second set of nozzle elements 123.

The operating mechanism for the nozzle arrangement may be enclosed by outer flaps 162 which overlap one another circumferentially and which are pivoted at their upstream edges to the annular casing 140 and are connest t h iedqwnstt am,edge ithmugh pivots 163 s? the downstream, edgesof. the nozzle elements 123 ofth' downstream set.

I claim:

1. A variable-area jet nozzle for a jet pipe comprising an even-numbered set of nozzle elements arranged fin' circumferential assembly, extending axially of .the jet pipe, and pivoted to the jet pipe at their upstream edges, a bracket 'pivotally connected to each alternate nozzle element, a pair ofioppositelyand-circumferentially;extending screw elements secured to said bracket, a gear box pivotally connected to each intermediatenozzleelement, said gear box comprising thrust bearing means, a pair of oppositelyand circumferentially-extending .nut elements supported in .said thrust bearing means to ,cooperate with the screw elements of adjacent nozzle elements ,the thrust bearing means preventing movement ofsaidnut elements axially ofthemselves relative tothe gear box;bu t permitting rotation of said nut elements, and said gear box alsocomprising a pair of bevel; gears, one-being connected to each nutelement, and a bevel pinion .to mesh with the pair of bevel gears, and means .to drive said bevel pinion, whereby on operation of said drive means the nut elements are caused to travel along the screw elements thereby to cause pivoting of the nozzle elements.

\ 2. A variable -areajet-nozzle asclaimed in claim 1, wherein saiddrive means comprises a circular rack ro tatable about the nozzle coaxially therewith, a set of rack-engaging pinions meshing with the rack to be driven thereby, there being one rack-engaging pinion for each of the bevel pinions, drive connections extending from said rack-engaging pinions to the bevel pinions, said drive connections being adapted to accommodate changes in the relative positions of the pinions, and motor means to rotate the rack.

3. A variable-area jet-nozzle as claimed in claim 2, wherein each of said drive connections comprises a shaft in two parts, a sliding splined connection between said shaft parts, and universal connections between the shaft parts and the associated pinions.

4. A variable-area jet-nozzle for a jet pipe comprising two even-numbered sets of nozzle elements, each set being arranged in circumferential assembly and extending axially of the jet pipe, the nozzle elements of the first set being pivoted at their upstream ends to the jet pipe, and the nozzle elements of the second set being aligned with respective nozzle elements of the first set and being pivoted at their upstream ends to the downstream ends of the respective nozzle elements of the first set; and means to effect pivoting of the nozzle elements comprising for each set of nozzle elements a bracket pivotally connected to each alternate nozzle element of the set, a pair of oppositelyand circumferentially-extending screw elements secured to said bracket, a gear box pivotally connected to each intermediate nozzle element of the set, said gear box comprising thrust bearing means, a pair of oppositelyand circumferentially-extending nut elements supported in said thrust bearing means to cooperate with the screw elements of adjacent nozzle elements of the set, the thrust bearing means preventing movement of said nut elements axially of themselves relative to the gear box but permitting rotation of said nut elements, and said gear box also comprising a pair of bevel gears, one being connected to each nut element, and a bevel pinion to mesh with the pair of bevel gears, the brackets associated with each set of nozzle elements being circumferentially aligned with the gear boxes of the other set of nozzle elements; and drive means to drive the bevel pinions, whereby on operation of the drive means the nut elements travel along the screw elements to cause pivoting of the nozzle elements.

5. A variable-area jet-nozzle as claim-ed in claim 4, wherein the drive means comprises an individual drive for each set of nozzle elements, each drive including a circular rack rotatable about the nozzle coaxially therewith, a set of rack-engaging pinions meshing with the rack to be driven thereby, there being one rack-engaging pinion for each of the bevel pinions, drive connections extending from said rack-engaging pinions to the bevel pinions, said drive connections being adapted to accommodate changes in the relative positions of the pinions, and motor means to rotate the rack, the circular racks being side by side and the rack-engaging pinions associated with one circular rack being circumferentially offset from those associated with the other circular rack.

6. A variable-area jet-nozzle as claimed in claim 5, wherein each of said drive connections comprises a shaft in two parts, a sliding splined connection between said shaft parts, and universal connections between the shaft parts and the associated pinions.

7. A variable-area jet-nozzle for a jet pipe comprising an even-numbered set of nozzle elements arranged in circumferential assembly, extending axially of the jet pipe and pivoted to the jet pipe at their upstream ends; a plurality of brackets, the number of brackets being half the number of nozzle elements; a number of gear boxes equal to the number of brackets, the bracket sand gear boxes being disposed in alternation around the nozzle and being pivoted each to a corresponding one of the nozzle elements, whereby each alternate nozzle element has a bracket pivoted thereto and each intermediate nozzle element has a gear box pivoted thereto; each gear box comprising a pair of bevel gears, thrust bearing means supporting said pair of bevel gears rotatively in said gear box with their axes tangential to the nozzle but preventing displacement of the bevel gears relative to the gear box axially of themselves, and a bevel pinion rotatively mounted in said gear box in mesh with said pair of bevel gears; a number of screw jacks equal to the number of said nozzle elements, each screw jack connecting an adjacent pair of said nozzle elements and each screw jack having a screw member and a co-operating nut member of which one member is secured to the bracket on one of the adjacent pair of nozzle elements and of which the other member is secured to rotate with one of the bevel gears of the gear box on the other of the adjacent pair of nozzle elements; and drive means connected to drive the bevel pinions of the gear boxes, whereby on operation of the drive means the nut members travel along the screw means to cause pivoting of the nozzle elements.

References Cited in the file of this patent UNITED STATES PATENTS 2,338,449 Malczewski Jan. 4, 1944 2,397,998 Goddard Apr. 9, 1946 2,509,238 Martin May 30, 1950 2,597,253 Melchior May 20, 1952 2,603,062 Weiler et al July 15, 1952 2,658,333 Smialowski Nov. 10, 1953 2,697,907 Gaubatz Dec. 28, 1954