US2791240A

US2791240A - Adjustable wall arrangement

Info

Publication number: US2791240A
Application number: US458652A
Authority: US
Inventors: Jr Harrison A Storms; Jr Robert P Davie
Original assignee: North American Aviation Corp
Current assignee: North American Aviation Corp
Priority date: 1954-09-27
Filing date: 1954-09-27
Publication date: 1957-05-07
Anticipated expiration: 1974-05-07

Description

May 7, 1957 H. A. STORMS, JR., E TAL ADJUSTABLE WALL ARRANGEMENT 6 Sheets-Sheet 1 Filed Sept. 27. 1954 A INVENTORS HARRISON A. STORMS, JR. ROBERT P. DAVIE, JR.

. ATTORNEY y 7, 1957 H. A. STORMS, JR., ETAL 2,791,240

ADJUSTABLE WALL ARRANGEMENT Filed Sept. 27. 1954 6 Sheets-Sheet 2 S,JR. JR.

NM NM R m NS A m A H ROBERT F. DAVIE 1111 11-11 111 1111. ML 1 11. .1111. ill].

FIG.2

May 7, 1957 H. A. STQRMS, JR, EI'AL 2,791,240

ADJUSTABLE WALL ARRANGEMENT Filed Sept. 27, 1954 6 Sheets-Sheet 3 INVENTORS HARRI A STO JR. ROBER DAVIE,

BY M4 dag AUIQBNEY y 1957 H. A. STORMS, JR.,'EIAL 2,791,240

ADJUSTABLE WALL ARRANGEMENT Filed Sept. 27. 195 1 e Sheets-Sheet 4 i 3 a ,v I ll 6 u IO lo r r l 24 7' r 92 n H I 13 INVENTORS HARRISON A. STORMS, JR. ROBERT F. DAVIE, JR. m M

ATTORNEY May 7, 1957 H. A. STORMS, JR., ETAL. 2,791,240

ADJUSTABLE WALL ARRANGEMENT 6 Sheets-Sheet 5 Filed Sept. 27, 1954 INVENTORS HARRISON A. sToRMs, JR. ROBERT P. DAVIE,JR. BY

ATTORNEI y 7, 1957 H. A. STORMS, JR., EIAL 2,791,240

ADJUSTABLE WALL ARRANGEMENT Filed Sept. 27. 1954 6 Sheets-Sheet 6 RESERWlR FIG. IO

INVENTORS HARRISON A. STORMS, JR. ROBERT E DAVIE, JR

FIG.8 I i I ATTORNEY 2,791,240 ADJUSTABLE WALL ARRANGEMENT Harrison A. Storms, Jr., Rolling Hills, and Robert P. Dav1e ,.Jr., Manhattan Beach, Calif., assignors to North American Aviation, Inc.

Application September 27, 1954, Serial No. 458,652 11 Claims. (Cl. 13845) This invention pertains to an adjustable wall arrangement and more particularly to an arrangement for varying the contour of a wind tunnel test section;

For a wind tunnel, especially a wind tunnel designed to operate at supersonic air velocities, it is desirable to provide a flexible nozzle arrangement whereby diflerent contours may be given to the nozzle as required for runs at various Mach numbers. This may be accom plished by providing a nozzle having two fixed side walls, and a pair of opposite movable walls, the latter being variable in contour to provide the shapes necessary for runs at desired speeds. Of course, for obtaining accurate results it is essential that the flexible walls of the nozzle be set exactly to the required configuration and it must also be possible to repeat such a setting. at will. Also, it should be possible to obtain the setting in a short time and retain it against forces exerted by the air passing through the nozzle. Various jack arrangements have been proposed which exert force against the walls to vary their shapes but all of these have lacked sufficient accuracy and repeatability of the setting.

Accordingly, it is an object of this invention to provide an adjustable wall arrangement whereby the walls may be setto an exact contour each time the shape thereof is changed.

Another object of this invention is to provide an adjustable wall arrangement having an infinite number of possible settings.

A further object of this invention is to provide an adjustable wall arrangement which is power driven and provided with a remote position indicating means.

Yet another object of this invention is to provide an adjustable wall arrangement which is relatively fast acting in obtaining a wall setting.

A still further object of this invention is to provide anadjustable wall arrangement which is rugged, dependable and' safe in its operation.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which Fig. l is a side elevational view of a portion of a wind tunnel including a nozzle with flexible walls;

Fig. 2 is a sectional view taken along line 2--2 of Fig. 1;

Fig. 3 is an enlarged fragmentary side elevation of the jack assemblies for varying the contour of a flexible wall;

Fig. 4 is a enlarged fragmentary sectional view taken along line 44- of Fig. 3;

Fig. 5 is a sectional view taken along line 5-5 of Fig. 2;

Fig. 6 is a sectional view taken along line 6-6 of Fig. 2;

Fig. 7 is a fragmentary elevational view of the common drive arrangement for opposite jack assemblies;

Fig. 8 is a schematic Wiring diagram of the indicator light hook-up;

hired States Patent" 0 Patented May 7, 1957 Fig. 9 is an enlarged fragmentary view, partially broken away, of the stop nut arrangements; and

Fig. 10. is a schematic view of the hydraulic drive for the actuating cylinders.

Referring to the drawings, a wind tunnel variable nozzle 1 is illustrated generally in Figs. 1 and 2. Such an installation will include fixed walls 3 and 4 and oppositely disposed

flexible walls

5 and 6, the latter being suitably sealed relative to the fixed walls. By such an arrangement and with sulficient supply' of pressurized air available, it is possible to provide a convergent subsonic nozzle with the flexible Walls in their fully retracted position, which can be altered to a convergent-divergent shape for supersonic air flow. In Fig. 1 dotted lines 5a and 6a represent the flexible walls in the subsonic position, while lines 5b and 6b illustrate the walls extended to the position for flow at maximum air velocity, which may be at approximately a Mach number of 5. This invention provides ameans for so positioning the

flexible walls

5 and 6 so that an infinite number of nozzle shapes between these two extremes is readily available.

Variation of the nozzle contour is obtained generally speaking by a plurality of jack assemblies 3 which include an adjustable remotely controlled stop means, a position indicating means to show the locations of the stops, and hydraulic cylinders to draw down against the stops and hold the walls inthe desired contour. The exact number of the jack assemblies which will be employed depends upon the size and capabilities of the wind tunnel.

Each jack assembly includes an inner cross beam 9 extending transversely of the wind tunnel and parallel to the flexible wall thereof. These beams are attached to the flexible wall of the tunnel in a suitable manner such as by a plurality of lugs lit attached thereto and pivotally engaging lugs 11 which are welded to the exterior of the tunnel wall (see Fig. 4). An outer transverse cross beam 12 is also included with each assembly, these beams being pivoted by bearings 13 to fixed supporting structure 14. As best seen in Fig. 4 this support for the outer cross beam includes interengaging tapering

tubular members

15 and 16, adjusted to a tight fit by wedge 17 fitting within offset

holes

18 and 19 and positioned by screw 20. Outer member 16 forms the shaft projecting into bearing 13.

Movement of the walls is obtained through hydraulic cylinders 22', rods 23 of which are threadedly received in beam 9. Two hydraulic cylinders are provided for each jack assembly, being fastened to outer beam 12 by bolts 24 so that movement of the rods 23 relative to the cylinders will effect adjustment of the wind tunnel wall. Due to the fact that the flexible walls will change considerably in contour there will be a certain amount of angular movement of the cylinders relative to the wall and to the fixed structure of the tunnel, this being provided by the pivotal connections 13 joining the outer beam to the fixed structure.

Also carried by beam 12 are adjustable stop assemblies 35 which serve to provide a proper setting so that the flexible walls can be given an exact contour. Each stop assembly includes a tube 36 which is rotatable relative to beam 12 in

bearings

37 and 38 which are carried by the beam. Within each tube is an elongated stop screw 39, one end of which is threadably received in beam 9. The outer end of the stop screw is supported and centered relative to the tube by means of a centering collar 40 which engages the inner wall of the tube. Screws 39 are not rotated relative to the beams once they have been installed.

Threadably received on each screw 39 intermediate its ends is a stop nut 41 which, as can be seen in Figs. 5 and 6, also engages a key 42 on the inner wall of the tube and extending substantially the length thereof. This 3 means that when th e tube is rotated in its bearings the key will cause stop nut 41 to rotate with the tube, and the threaded engagement of the stop nut with the stop screw will cause the stop nut to assume a position along the length of the stop screw in accordance with the amount of rotation which has been given the tube.

Included with beam 12 and held thereto is a stop plate 44 which is engageable by stop nut 41. The general action of the stop screw and nut can now be seen. By rotation of tube 36 the stop nut may be positioned axially relative to the stop screw so that it is spaced from stop plate 44. If cylinder 22 is then pressurized the connecting rod 23 can be extended moving the flexible wall until the stop nu. is brought into engagement with the stop plate. In Fig. 4 the stop nut is shown in an intermediate position while in Fig. 9 the nut can be seen in engagement with the stop. This fixes the position of the flexible wall at the location of the jack assembly involved.

The tubes 36 at each of the jack assemblies are caused to rotate equally and simultaneously so that both of the stop nuts will be given exactly the same setting. For this reason there is provided a chain drive extending between the two tubes of each of the jack assemblies. Each tube is provided with a sprocket 47 secured thereto in a suitable manner so that the sprocket and the tube rotate together (see Fig. There are likewise provided pairs of

idler sprockets

48 and 50. The latter two are carried by brackets 53 which are fixed by bolts to the beam assembly. Sprockets 48 are carried by brackets 56, each of which is provided with guide pins 58 and a central projecting screw 59 these elements being received in bracket member 61. Adjustment of nut 62 on screw 59, loaded by spring 60, will accordingly set the lateral position of the sprocket member and will also control the tension on the chain 63. This means that the two tubes 36 can be adjusted to the identical angular position and uniform rotation without backlash can be obtained.

The rotation of the two tubes is accomplished by means of a sprocket 64 secured to the outside of one of the tubes 36 and engaging a chain 66 extending

past idlers

67 and 68 to a second sprocket 69 rotatably carried by the fixed structure of the tunnel, as best seen in Figs. 4, 6 and 7. A shaft 70 engages the latter sprocket for effecting rotation thereof, this shaft being driven through gear box 72 by means of an electric motor 73. Preferably, as illustrated in Fig. 7, the drive shafts 70 for oppositely disposed jack assemblies are attached to a common gear box, because equal and simultaneous adjustment of these units is desired. Associated with one of the rotating elements of this drive such as with shaft 74 of the gear box, is a counter 75 which will give the exact number of revolutions given to the shaft and thus will indicate the amount of rotation of the tubes 36. This in turn records the number of revolutions for the stop nuts and, when calibrated to a known reference position, will be an indication of the axial positions of the stop nuts. Therefore, in setting the contour of the wind tunnel tubes 36 may be rotated by means of the motor 73 until the shaft 74 has turned a certain predetermined number of revolutions. This indicates exactly where the stop nuts are so that when the hydraulic cylinders force the stop nuts against the stop plates the wind tunnel at that location will be given a predetermined contour. If the setting is changed it can be readily reset by merely rotating the shaft until that particular number of revolutions is indicated in the counter whereupon actuation of the hydraulic cylinders will bring the flexible plates exactly back to their earlier set position. In this manner the desired contour of the nozzle can be set at each jack station and predetermined to an exact value. The setting can be attained in a very short time and can be repeated at will. t the same time an infinite number of positions can be given the stopnuts so that any desired contour of the flexible walls can be realized.

When the flexible walls are to be set to the desired configuration and a test is to be run in the wind tunnel the hydraulic cylinders are operated under a relatively low pressure until the stop nuts are practically in position adjacent the stop plate. Then when the test is run a high pressure is introduced into the hydraulic cylinders so that the flexible walls will be held in place against the relatively large forces which will be exerted thereagainst by the air passing through the nozzle. In order that it can be determined exactly when the stop nuts have reached the stop plates and therefore so that the large pressure can be introduced in the hydraulic cylinders, an automatic indicating means is provided with the jack assemblies of this invention. As shown in Fig. 8 an indicator light 80 is connected through

conductors

81 and 82 to a suitable source of electric power 83 the current to the light being controlled by means of switch 84. The operation of the switch can best be seen by reference to Fig. 9. As illustrated, stop nut 41 includes an extension 86 having a bevelled end 87 thereon which projects beyond the stop plate when the stop nut is in position thereagainst. A plunger 88 loaded by spring 89 so that it is biased inwardly is adapted to engage stop screw 39 when in its inward position, the opposite end thereof being adapted to engage actuating arm 90 of switch 84. When in this position the switch is open so that no current is conducted to the indicating light. Then when the stop nut is brought into its position engaging the stop plate, however, bevelled end 87 thereof forces the plunger outwardly thereby moving actuating arm so as to close the switch and light the indicator light. This shows that the stop nut is in its position at the stop plate and high pressure can then be introduced into the hydraulic cylinder.

A second and fixed stop nut 91 is also provided with the jack assembly, this being adapted to engage stop plate 92 on the opposite side of the beam 12 from stop plate 44. Stop nut 91 limits the outward movement of the stop screw and is preferably set in a position whereby when it is engaged the flexible walls of the tunnel will form a convergent nozzle which will permit attainment of a Mach number of 1. This fixes the lower speed range of the nozzle.

This stop nut does not rotate on the stop screw being locked relative thereto in any suitable manner. In the design shown this comprises a slot 93 extending part way circumferentially around the nut. When screw 94 is tightened the slotted portion of the nut is deflected enough to lock against the threads of the stop screw and prevent rotation.

A second indicator light 95 is connected through

conductors

96 and 97 to the source of electrical energy and is controlled by normally open indicator switch 98. Plunger 99 is loaded by spring 100 and adapted to engage the actuating arm 101 of switch 98 exactly as plunger 88 operates with switch 84. The end 102 of fixed stop nut 91 is also bevelled so that when this stop nut is moved against stop plate 92 it forces the plunger outwardly thereby closing switch 98 and lighting the indicator light to show that the tunnel is then at its slow speed setting for providing a Mach number of 1 in the test section. As illustrated in Fig. 9 the flexible wall is retracted and in position for a slow speed run because nut 94 is in engagement with its stop plate.

The hydraulic arrangement for the cylinders 22 is shown schematically in Fig. 10. Reservoir 104 supplies pump 105 the outlet of which is connected to accumulator 106 supplying pressurized hydraulic fluid to line 107. Shut-off valve 108 in this line permits throttling of the outlet pressure while relief valve 109 prevents over pressuring the system. Inlet line 107 leads to each of the jack assemblies. At each it connects to a three way valve 110 also connected to lines 112 leading in turn to one end of each of the cylinders 22 of the jack assembly. Line 107 also connects to three way valve 114 which, through lines -"1 1 5 connects with the opposite ends of cylinders 22'. Lines" 116 and 117 connect

valves

110 and 114 to return 118. As illustrated in 'Fig. the valves are ported so as to admit pressure in one end of the cylinders 22 so that pistons 120 will cause movement of beam 9 and the flexible tunnel wall. Valve 114 permits displaced fluid to enter the return line. Reversal of the valves will cause opposite movement of the pistons.

It can be seen from the foregoing that we have provided an improved flexible wall arrangement wherein the wall contour can be rapidly set with extreme accuracy. The design is simple and rugged, yet permits an infinite number of wall contours with perfect repeatability of the settings. The chain drive arrangement allows thestop nuts of eachassembly to be perfectly correlated in their movement and virtually eliminates the effects of backlash.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited by the appended claims.

We claim:

1. A device for effecting adjustment of a flexible wind tunnel wall comprising a projecting member extending from and movable with said wall, a movable mechanical stop movable with and positionable relative to said projecting member, a fixed mechanical stop engageable by said movable stop, means for predeterminately positioning said movable stop relative to said projecting member, and means for moving said wall to bring said stops into interengagement.

2. A device for effecting movement of a movable wind tunnel wall comprising a stop screw connected with said wall and movable therewith, a stop nut threadably received on said stop screw, a fixed stop engageable by said stop nut, means for effecting rotation of said stop nut relative to said stop screw thereby to vary the axial position of said stop nut on said stop screw, means for indicating the axial position of said stop nut, and means for moving said wall to a position where said stop nut engages said stop.

3. A device for effecting movement of a flexible wind tunnel wall, said device comprising a stop screw connected to said movable wall, a stop nut threadably engaging said stop screw, a fixed stop engageable by said stop nut, tube means surrounding said stop screw and rotatable relative thereto, said tube means operatively engaging said stop nut so as to rotate the same therewith while permitting axial movement of said stop nut relative thereto and relative to said stop screw, means for indicating the axial position of said stop nut, and means for moving said wall to a position whereby said stop nut is brought into engagement with said stop.

4. A device for effecting adjustment of a movable wind tunnel wall, said device comprising a duality of stop screws pivotally connected to said wall and projecting outwardly therefrom, a stop nut threadably engaging each of said stop screws, stop means axially fixed relative to said stop screws and engageable by said stop nut-s, rotatable means operatively engaging each stop nut for effecting rotation thereof relative to the stop screw engaged thereby for adjusting the axial positions of said stop nuts, means for effecting simultaneous rotation of said rotatable means whereby said stop nuts are simultaneously adjusted, means for indicating the axial positions of said stop nuts, and means for moving said wall until said stop nuts are brought into engagement with said stop means.

5. A device for adjusting the contour of a flexible wind tunnel wall said device comprising a duality of stop screws pivotally connected to said wall and projecting outwardly therefrom in spaced parallelism, beam means adjacent portions of said stop screws remote from said wall, means for pivotally supporting said beam means at such position, a stop' nut threadably engaging each of said stop screws whereby rotation of said stop nuts effects axial adjustment thereof relative to said stop screws, drive means rotatably carried by said beam means for effecting rotation of said stop nuts for effecting such axial adjustment, stop means carried by saidbeam means and engageable by said stop nuts, means engaging said wall for effecting movement thereof to a position where said stop nuts are brought into engagement with said stop means, means for effecting equal and simultaneous rotation of said drive means whereby said stop nuts are given equal and simultaneous axial adjustment, and indicator means for indicating the axial adjustment of said stop nuts.

6. In combination with the flexible wall of a wind tunnel, a device for effecting adjustment of said wall comprising screw means, means for connecting said screw means to said flexible wall so that said screw means projects therefrom and is axially fixed relative thereto, stop nut means on said screw means and rotatable relative thereto, a fixed stop means engageable by said stop nut means, power driven means connected to said flexible wall for moving the same together with said screw means to a position where said stop nut means engages said stop means, means for rotating said stop nut means relative to said stop screw means to thereby vary the axial position of said stop nut means relative thereto, and means for indicating the axial position of said stop nut means relative to said screw means.

7. In combination with a flexible wall, a device for effecting adjustment of said wall, said device comprising a screw, means for connect-ing said screw to said flexible wall so that said screw projects outwardly from said wall and is axially fixed relative thereto, a stop nut threadably engaging said screw whereby upon relative rotation of said stop nut and said screw said stop nut is axially adjusted relative thereto, a fixed stop engageable by said stop nut, hydraulic means engaging said wall and operative to move said wall to a position whereby said stop nut is brought into engagement with said stop, means for effecting relative rotation of said stop nut and said stop screw, and counter means for indicating amount of such relative rotation to thereby indicate the axial position of said stop nut relative to said screw means.

8. In combination with a flexible wall, a device for effecting adjustment of said wall comprising a duality of screw means connected to said wall, a stop nut on each of said screw means, said stop nuts being rotatable relative to said screw means whereby such relative rotation effects axial adjustment of the positions of said stop nuts relative to said screw means, fixed stop means engageable by said stop nuts, chain drive means for effecting equal and simultaneous relative rotation of said stop nuts and screw means, remote indicating means for indicating the axial positions of said stop nuts relative to said screw means, and power driven means connected with said flexible wall for effecting movement thereof to a position whereby said stop nuts are brought into engagement with said stop means.

9. A device for adjusting a flexible Wind tunnel wall comprising a first beam pivotally connected transversely to the exterior of said wall, a stop screw connected to and projecting from said first beam, a second beam, means for pivotally supporting said second beam spaced from said first beam, a stop on said second beam, a stop nut threadably engaging said stop screw and adapted to engage said stop for limiting the axial travel of said stop screw, 2. tube surrounding said step screw and rotatably supported by said second beam, said tube including means providing a rotational driving connection with said stop nut while permitting relative axial movement whereby rotation of said tube effects rotation of said stop nut and varies the position thereof axially relative to said stop screw, means for rotating said tube, means for indicating '7 the amount of such rotation, and actuating means carried by said second beam and operatively engaging said first beam for moving said first beam to a position where said stop nut engages said stop.

10. A device for effecting adjustment of a flexible wind tunnel wall comprising a first beam connected to said wall and extending transversely thereof, a duality of stop screws secured to said first beam and projecting therefrom, a second beam, means for pivotally supporting said second beam in spaced parallelism with said first beam, a first stop nut threadably engaging each of said stop screws whereby rotation of said first stop nuts relative to said stop screws effects axial adjustment of said stop nuts relative thereto, a first stop means on said second beam for engagement by said first stop nuts, thereby to limit the axial travel of said stop screws in one direction, a tube in surrounding relationship with each of said stop screws, said tubes being rotatably supported by said second beam and drivingly engaging said first stop nuts for effecting axial adjustment thereof, chain drive means interconnecting said tubes whereby said tubes are equally and simultaneously rotatable, a second stop means on said second beam, a second stop nut on each of said stop screws adapted to engage said second stop means for limiting the axial travel of said stop screw in the opposite direction, said second stop nuts being axially fixed relative to said stop screws, and actuating means carried by said second beam and engaging said first beam for exerting a force on said first beam thereby to position said flexible wall.

11. In a wind tunnel a variable nozzle comprising two opposite fixed walls, and two opposite flexible walls adjustable in contour, each of said flexible walls having stop screw means projecting outwardly therefrom, a stop nut threadably received by said stop screw means whereby rotation of said stop nut relative to said stop screw means effects axial adjustment of said stop nut relative thereto, a fixed stop engagea'ble by said stop nut, actuating means connected with said flexible wall and operative to move said wall to a position whereby said stop nut is brought into such engagement with said stop, said opposite flexible walls having a common means for effecting equal and simultaneous rotation of said stop nuts relative to said stop "screw means, and indicating means for indicating the amount of such relative rotation.

References Cited in the file of this patent UNITED STATES PATENTS 1,900,677 Weidhaas et al Mar. 7, 1933 2,462,953 Eaton et a1. Mar. 1, 1949 2,472,949 Jackson June 14, 1949 2,560,634 Colley July 17, 1951 2,589,896 Toland Mar. 18, 1952