US2462953A - Adjustable cone orifice - Google Patents

Description

March 1, 1949.

Filed Feb. 5, 1946 E. D. EATON ET AL ADJUSTABLE CONE ORIFICE 6' Sheets-Sheet 1 March 1, 1949.

Filed Feb. 5, 1946 E. D. EATON ETAL 2,462,953

ADJUSTABLE CONE ORIFICE 6 Sheets-Sheet 2 March 1, 1949. E. D. EATON ETAL 2,462,953

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(-flllow'zzr iy March 1, 1949. E. D. EATON ET AL" ADJUSTABLE CONE ORIFICE Filed Feb. 5. 1946 6 Sheets-Sheet 6 Patented Mar. 1, 1949 ADJUSTABLE CONE ORIFICE Edwin D. Eaton, Bloomfield, Conn., and Francis W. Catudal, Providence, R. 1., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application February 5, 1946, Serial No. 645,576

20 Claims. (01. 230-120) This invention relates to adjustable orifices and particularly to an adjustable orifice for modifying or controlling fiuid fiow, especially in wind tunnels or airplane propeller test houses.

Airplane propellers in being tested are operated in test cells which may be either the straightthrough type or the so-called U-shaped design. In the U type, both the intake and exhaust stacks are vertical while the chamber between them, in which the propeller is tested, is horizontal. In the straight-through type of test cell both the intake and exhaust stacks, as well as the chamber connecting them, are horizontal. In testing propellers in the above types of test houses and particularly while conducting vibratory stress measurements on the propellers, conditions have been encountered which indicated that an aerodynamic excitation was present which resulted in prohibitively high vibratory stresses in propeller blades under test. This condition is encountered more frequently as the propeller size and engine horsepower ratings increase. 1

This aerodynamic excitation appeared to be caused by an unsymmetrical and irregular fiow of air through the propeller disc due primarily to recirculation. The U-shaped test cell produced an aerodynamic excitation which, in gen-' eral, was found to be more severe than the excitation in the so-called straight-through type; but even in the straight-through type, many instances were encountered where prohibitively high aerodynamic stresses were induced. The recirculation, which it was believed produced the aerodynamic excitation, was caused by the overall drag or resistance to the flow of air through the test house, which resistance is due largely to the soundproofing in the intake and exhaust stacks, and also to the resistance of structures, such as engine mount, work platforms, etc., located in the test cell. This drag or resistance induced pressure difierences which caused the air, energized by the propeller, to recirculate from the rear to the front of the propeller and, in circulating, produced the unsymmetrical and irregular flow of air through the propeller disc.

An attempt to overcome this difiiculty was made by use of what is known as an Allison door which consisted of a sharp-edged orifice mounted directly behind the propeller and having an opening somewhat smaller than the diameter of the propeller to be tested. The door thus divided the test cell into two sections, ex-

around the propeller tips. While this was some improvement in some installations, it was found that in other installations it made very little, if any, improvement. Another method for preventing recirculation was a fixed cone-shaped orifice in which the propeller disc was located approximately in the plane of the small diameter orifice of the cone and in which the propeller tips operated in very close proximity to the edge of the orifice. This structure was workable only if the tip clearance was maintainedvery small so that it would be impossible for the air to recirculate through the propeller disc. This construction required a different cone for every propeller diameter and was, of course, impractical.

An object of our invention is an adjustable orifice.

Another object of our invention is an orifice which may be adjusted both in diameter and position in the fiuid stream.

Another object of our invention is a selfcontained adjustable cone orifice and means for adjusting the orifice.

A'further object of the invention is a propeller test cell having a cone orifice adjustable to the plane and diameter of the propeller being tested.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate what is now considered to be a preferred embodiment of the invention.

In the drawings:

Fig. 1 is a vertical sectional view of a propeller test cell and the adjustable cone; M

Fig. 2 is a side elevation of the cone shown in section in Fig. 1;

Fig. 3 is an end elevation taken along thelines 3-3 of Figs. 1 and 2 looking through the smaller end of the cone;

Fig. 4 is an enlarged view of the wrapper cable winding drums shown in the upper right hand portionof Fig. 3;

Fig. 5 is an enlarged view of the lock for holding the cone in adjusted longitudinal position;

Fig. 6 is a plan view taken along the lines 6-6 of Fig. 2 showing one set of wrapper cable and radial cable winding drums;

Fig. 7 is a sectional plan view taken along lines 'l'! of Fig. 2 with the center portion broken away;

Fig. 8 is a detail of the wrapper cable tensioning means and Fig. 9 is a section along lines 99 of Fig. 8;

Fig. 10 is a detail of the radial cable adjusting means;

Fig. 11 is a side view of the radial cable anchoring means:

Fig. 12 is a sectional view of the anchoring means taken along lines I2-I2 of Fig. 19;

Fig. 13 is a detail of the hinge mounting of the cone plates or leaves;

Fig. 14 is an enlarged transversesection of a portion of the cone showing the connections of the intermediate wrapper cable;

Fig. 15 is an end view showing the connections of'the end wrapper cable;

Figs. '16, 1'7, 18, and 19 are detail views of one of the inner plates or leaves; and

Figs. 20, 21, 22 and 23 are detail views of one of the outer plates or leaves.

The adjustable cone incorporating the invention of this application is shown mounted in a propeller test cell indicated generally at 88 and having soundproofing 32 at the intake portion 34 and soundproofing 36 in the exhaust portion 38. A platform 48, extending between the side walls of the test cell 38, supports an enclosure 42 having an entrance 44 midway between the side walls. Enclosure 42 may contain propeller and engine operating controls and accessories. An engine mount 46, located at one end of enclosure 42, supports engine 48 and propeller 58 driven by that engine. If desired, a similar engine support may be located at the opposite end of enclosure 42.

The adjustable cone, indicated generally at 52, is mounted on wheels 54 to roll longitudinally of test cell 38 on tracks 56 and is held in adjusted position by stops or looks generally indicated at 58. Stops 58 each comprise rack section 68 (Fig. slidably mounted ina guide 62 and adjustable in that guide by a wheel 64 secured to a nut 66 operating on a threaded bolt 68 attached to the rack sections 68. Guide 62 is supported upon the framework indicated generally at 18 of the adjustable cone. Rack section 68, when projected outwardly by operation of the wheel 64, meshes with rack I2 secured to the side wall of the test cell. As indicated in Fig. 3, a' stop is providedfor each side of the orifice framework I8.

In general, the orifice comprises a series of 1 overlapping plates or leaves I4, I6 hinged at one end to a polygonal cylinder 18 which, through intervening platesand brackets, is supported on the framework I8. Alternate plates overlap, thus forming a series of inside plates and a series of outside plates overlapping the inside plates to form a closed tube. The plates are movable about the hinges at one end of each plate by means of two series of cables; one set of cables is attached to the inside plates only and pull radially outward to move the inside plates outwardly and, because the outside plates overlap the inside plates, also move the outside plates outwardly to expand the opening at one end of the tube formed by the overlapping leaves. The other set of cables surrounds all the leaves and is woven through guides or supports which may be rollers or sheaves on each leaf. There are two sets of these cables known as wrapper cables which act to contract the end of the tube formed by the leaves opposite the hinged connection. These wrapper cables act in a manner similar to a puckering string to draw all the plates in. This action is opposed by the radial cables attached to the inner plates. The radial cables are of a fixed length and determine the position of the tube-forming plates and the wrapper cables are spring loaded and act to hold the radial cables under tension and the plates in position against the action of the radial cables. The radial cables are led over pulleys to four sets of cylindrical spiral grooved winding drums, one set being s cated in each comer of the substantially square framework I8, two additional drums for the wrapper cables are mounted on the shafts supporting the cylindrical; drums in the two upper corners. The drums areall connected together by means of a series of shafting and gearing, the shafting extending along three of the four sides of the framework so that the operation of all the drums is synchronized.

Specifically, a framework indicated generally at I8 built up of'structural members forms a frame having a restangular cross section which substantially fills the rectangular or square tube 38 forming the test cell. A flexible packing 88,

secured to the framework I8, acts to seal the 2 joint betweenthe framework and the sides of the test cell. Pendentives 82, supported from and located at each corner of the framework, transform the rectangular section at the test cell to a polygonal substantially circular section at the g5 hinged ends of the orifice forming plates I4, I8. The polygonal cylinder 18 supporting lugs 84, 86, 88, and 88 forming one part of the hinges for the plates "I4, I6 is located between the pendentives and the framework 18. Each inner plate carries 0 a hinge part 82 which is located between lugs 84 Q and 86 on cylinder 18 andthe hinge is completed by a pin which passes through lug 84, hinge part 82, and lug 86. Each outside plate carries a hinge part 84 which is located between lugs 88 3s and 88. The hinge for the outer plate is completed by a hinge pin which passes through lug 88, hinge part 84 and lug 88., The outer plates are located between and overlap the inner plates around the entire circumference of the cylinder I8. The hinges above described thus support the forward end of the inner and outer plates I4, I6 on the framework and position the plates to form the forward end of a tube; the other or rearward end of which may be expanded or contracted to form the variable orifice. Each of the inner plates I4 is supported against inward movement about its hinge 84, 82, 86 by a radial cable 86. Each inner plate has its own independent cable; one end of which is secured to the plate I4 by means of a terminal block 88 hingedly mounted on pins I88 which in turn, are supported in lugs I82 secured on the outside of plate 14. Each cable 86 is led substantially radially outward from the plate I4 through a fixed sheave I84, an adjustable sheave I86, and a second fixed sheave I88 to a cylindrical windin drum II8 to which it is attached as may be clearly seen in Fig. 3. The radial cables are divided into four groups and, in the embodiment shown, each group comprises four cables. The

groups are all similar and the cables of each group are led to a cylindrical drum IIII located in the corner of the framework adjacent that group. Each cylindrical drum is gear driven through gears, H2, H4, a reduction gear box 6, and a pair of beveled gears I I8, I28. A series of shafts I22, I24, I26 are geared together for simultaneous and equal rotation and extend respectively along one side, across the top, and down the other side of the framework I8. Beveled gears I28, secured to shafts I22 and I26, drive the several drums I I8 in synchronism, thus winding up cables 86 and moving each plate I4 outwardly the same distance and thus simultaneously enlarging the orifice defined by the inner by two sets of wrapper cables I32 and I34. Cable I32 is threaded through guides I36 on the rear ends of plates 14 and through guides I38 on the rear end of plate 16. One end of cable I32 is secured to a conical drum mounted on the same shaft with one of the cylindrical drums IIIJ; it then passes over a fixed sheave I42, an adjustable sheave I44, another fixed sheave I46, a universally mounted sheave I48 supported on the framework 10, through a sheave I50 universally mounted adjacent guide I36 on an inner plate'14, through a double guide I52, alternately through guides I36 and I38 completely around the outside of the group of plates 14, 16 back through the double guide I52, through a sheave I54 universally mounted adjacent to a guide I36 on a plate 14 similar to sheave I50 carried by adjacent plate 14, and then in reverse order to that described above through a series of universally mounted, fixed and adjustable sheaves I48, I46, I44, and I42 mounted on the framework 10 back to a cone winding drum I40 located in the opposite upper corner of the frame work from the firstmentioned drum I40. Like the first-mentioned drum I40, the last-mentioned drum I40 is mounted on the same shaft with a cylindrical drum III) and has one end of the cable I32 anchored therein.

Wrapper cable I34 is similar in mounting and action to cable I32 but is located intermediate the ends of the plates instead of adjacent one end. Like cable I32, I34 starts at a conical drum, passes through fixed, adjustable and universally mounted sheaves to guide members carried by the plates 14 and 16 completely around the plate assembly and through another series of sheaves back to a winding drum on the opposite side of the framework. The cables 96, I32 and I34 are so wound on their respective drums that rotation of the drums to wind up the cables 96 will pay out cables I32 and I34 and vice versa. Hence, operation of the drums will cause plates 14 and 16 to move about their hinges to vary the opening of the orifice defined by the rear ends of the plates. Although the cables have been shown as passing under and over fixed guides such as I36 and I38, it will, of course, be understood that, if desired, pulleys or other friction reducing means might be used in place of the fixed guides.

The interior-of plates 14 and 16 are each curved so as to make the cone or tube formed by the plates and the orifice defined by the rear end of the plates as nearly a true circle as possible; the interior of the outside plates 16 are formed to a fixed radius. In the embodiment shown therein, that radius is fifteen feet, three inches. The exterior of the inside plates is formed to the same radius so that when the plates are moved outward to form. an orifice of the largest diameter, that is thirty feet and six inches, the plates are substantially in mating relation. As the rear ends of the plates are drawn inwardly to form a smaller diameter orifice, the edges of the inside plates rub on the interior surface of the outside plates to maintain a substantially closed tube or cone and also maintain as nearly as possible a circular cross section. I

As indicated above, each cable 96 passes through an adjustable sheave I06 (see Fig. 10). Sheave I06 may be adjusted by means of a bolt I56 and a nut I58 to accurately position each inside plate 14. The plates may thus be made to bring the adjustable orifice into a concentric position with the propeller to be tested. In the test house the propeller is located concentric with the cylindrical member 18 so that when the rear ends of the plates 14 are adjusted to be concentric with the propeller, they are also concentric with the plates 18 and adjustment, by means of the winding drums, maintains this concentricity.

As indicated above, the cables I32 and I34 pass through adjustable sheaves I44. The adjustment of these sheaves, however, is not fixed but, as indicated in Fig. 8, they are spring mounted so that a spring I60 maintains the cables under a predetermined tension. This tension may be adjusted by means of bolt I62 and nut I64. This spring mounting takes up any irregularities that there may be in machining or irregularities that may be caused by angularity of the various cables.

The wrapper cables I32 and I34 are wound on cone-shaped drums I40 and I66 respectively instead of cylindrical drums to compensate for the angularity of the cable and the variable relation between the universally mounted sheaves I50, I54 and I48, I48 for cable I32 and similar sheaves not described but acting in a similar manner for cables I34.

A cable I68 extending radially from the rear end of one of the plates 16 passes over a pulley fixed on the framework 10 and down to a pointer I10 movable over a scale I12 to indicate the extent of opening of the variable orifice.

Electric motor I14, driving through a reduction gear I16, drives an axle I18 extending across the lower part of the framework 10 to drive the wheels 54 on which the framework is mounted and thus move the framework longitudinally of the test cell 30. In order to prevent over travel of the framework, stops in the form of switches are provided to discontinue operation of the motor when the limit of travel is reached.

Similar cutouts are provided to prevent overtravel of the winding drums operating the plates, 14, 16 so that when the limit of travel in either direction is reached, the switches are actuated to discontinue further operation of the motor I30.

In operation after the propeller 50, which is to be tested, has been mounted in position on propeller driving engine 48, the framework 10, carrying the adjustable cone orifice, is adjusted longitudinally of the test cell 30 by operation of the motor I14 until the rear ends of the plates 14, 16 are located approximately in the plane of or slightly overlapping the propeller disc. Motor I30 is then operated to adjust the cone orifice to a diameter only slightly larger than the diameter of the propeller. If the device is in'adjustment, the orifice thus formed will be concentric with the propeller. If it is found tobe eccentric, it can be adjusted by means of theadjustable sheaves I06 to bring it concentric with the propeller. If necessary, the framework 10 may again be adjusted longitudinally so as to bring the adjusted orifice into the plane of or slightly to the rear of the propeller disc. Although the pressure to the rear of the propeller may be greater than the pressure in front of the propeller, air cannot pass through the propeller disc because of the rearward thrust of the propeller and it cannot pass around the pro- 7 peller tips because the cone will prevent such action. Recirculation is-thus effectively eliminated and the propeller may be tested without the danger of stressescaused by recirculation.

It ls to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

For instance, the adjustable cone orifice has been'described in connection with a propeller test cell, but the invention is not limited to that particular structure and could also be used in wind ,tunnels in the form of an adjustable throat or venturi. In such case, two adjustable cones in connection with anadjustable cylinder between them using the same system of cables and segment plates as above described could be used.

We claim:

1. In combination with an aerodynamic test cell adapted to confine moving air, an adjustable cone orifice located in said test cell and also con fining said moving air.

2. In combination with an aerodynamic test cell adapted to confine moving air, a restriction at the discharge end of said cell, tending to cause recirculation of said moving air in said cell and an adjustable cone orifice located in said test cell and restricting the recirculation air movements in said cell.

3. In combination, means for forming an adjustable orifice comprising overlapping leaves, a framework supporting said leaves, mechanism supported on said framework for simultaneously moving said leaves, said mechanism comprising means for drawing the leaves in, and means for positively moving said leaves outwardly and means operable in one direction for simultaneously operating one of said means'and releasing the other of said means and operable in the other direction for simultaneously operating said other means and releasing said one means. I

4. In combination, overlapping elongated leaves I radially of said leaves and connecting said leaves with said framework, means for simultaneously moving said cbnnectionaradially outward to move said leaves outwardly and spring means urging said leaves inwardly.

5. In combination with a plurality of overlapping inner and outer elongated leaves hinged at one end on a support to define a substantially fixed orifice, means for moving said leaves about said hinges to adjust the size of the orifice formed by the other end of said leaves, said moving means comprising, a plurality of cables arranged to pull outwardly on the inner leaves, and means for simultaneously moving all of said cables, and means resiliently forcing the outer leaves inwardly against the inner leaves.

6. In combination, an inner series of substantially rectangular leaves and an outer series of substantially rectangular leaves arranged in overlapping relation with said inner series, and forma ing a conduit open at both ends, hinges connecting'one end of said leaves to a support to define a substantially fixed orifice,'and means for moving said leaves about said hinges to adjust the size of .the free end of said leaves and connected with each of said leaves,.and means for moving said last-mentioned cable simultaneously with said plurality of cables.

-'7. A structure as defined in claim 6 in which said movingme'ans comprises a plurality of drums to which said cables are attached, and means for rotating said drums to-wind up or unwind said cables. i

8. Testing apparatus comprising a tubular member having an entrance and discharge, means defining an adjustable orifice between said entrance and discharge comprising, a framework, a plurality of overlapping leaves hingedly supported at one end in said framework and defining a conduit within said tube, means for moving said leaves about said hinges to vary the size of the orifice defined by the opposite ends of said leaves, andmeans for moving said framework and said conduit longitudinally of said tube to vary the position of said adjustable orifice in said tube.

9. In a test chamber'comprising an elongated tubular member having an entrance end and a discharge end, a framework within said tubular member, an inner series of substantially rectangular plates and an outer series of substan-- tially rectangular plates overlapping said inner series and forming with said inner series a conduit within said tubular member, hinges connecting said leaves to said framework, means substantially closing the space between said leaves and said tubular member, and means for moving said leaves about said hinges to vary the size of the orifice formed by one end of said leaves.-

10. A test chamber comprising an elongated tubular member having an entrance and and a discharge end, a framework within said tubular member, an inner series of substantially -rectangular plates and an outer series of substantially rectangular plates overlapping said inner series and forming with said inner series a substantially air-tight conduit within said tubular member, hinges connecting one end of said leaves to said framework, means adjacent said hinges substantially closing the space between said leaves and said tubular member, and means for moving said leaves about said hinges to vary the size of the orifice formed by the other end of said leaves.

11. In a test chamber comprising an elongated tubular member having an entrance end and a discharge end, a framework within said tubular member, means for substantially closing the space between said framework and said tubular member, an inner series of substantially rectangular plates and an outer series of substantially rectangular plates overlapping said inner series and forming with said inner series a conduit within said tubular member, hinges connecting said leaves to said framework, means substantially closing the space between said leaves and said framework adjacent said first-mentioned space closing means, means for moving said leaves about said hinges to vary the size of the orifice formed by one end of said leaves, means movably supporting said framework in said tubular mem- 9 her, means for moving said framework and the conduit supported thereby longitudinally of said tubular member, and means for locking said framework in adjusted position in said tubular member.

12. In a propeller test cell, means for supporting a propeller and means for rotating said propeller in a, substantially fixed position in said cell, means for preventing recirculation of fluid around said propeller comprising, a conduit formed by an inner series of leaves and an overlapping outer series of leaveshinged to a support, means for adjusting said leaves about said hinges to bring one end of said leaves substantially into the plane of, closely adjacent to, and surrounding said propeller, said leaves and said support substantially blocking said test cell except for the area defined by the adjustable orifice end of said leaves.

13. In a propeller test cell, means for supporting a propeller and means for rotating said propeller in a substantially fixed position in said cell, means for preventing recirculation of fluid around said propeller comprising, a conduit formed by an inner series of leaves and an overlapping outer series of leaves hinged to a support, means for adjusting said leaves about said hinges, and means for adjusting said leaves 1ongitudinally of said cell to bring one end of said leaves substantially into the plane of said propeller and closely adjacent to, but surrounding said propeller, said leavesand said support substantially blocking said test cell except for the area defined by the adjustable orifice end of said leaves.

14. In a propeller test cell for testing propellers of various sizes, means for preventing recirculation of air comprising, a conduit made up of a plurality of overlapping leaves, hinges connecting said leaves to a support in said test cell. said conduit surrounding said propeller and extending from said propeller toward the entrance of said test cell, means for adjusting the ends of said leaves adjacent said propeller to define an orifice of substantially the same diameter as the propeller, means supporting said leaves against inward movement due to the pressure differential on opposite sides of said leaves, means for holding said leaves against expansion and against said supporting means, and means including said means comprising, a plurality of cables secured to and extending radially from said inner series of leaves, drum means for simultaneously pulling in or paying out said cables, a wrapper cable extending around said leaves, drum means for paying out or pulling in said wrapper cable, and means for simultaneously actuating all of said drum means.

16. A device as claimed in claim 15 in which the drum means for the wrapper cable is a conical drum.

17. A device as claimed in claim 15 having means for individually adjusting the position of each of the inner series of leaves by adjusting the length of its supporting cable, and resilient means for tensioning the wrapper cable.

18. In combination with an aerodynamic test cell adapted to confine moving air, an adjustable cone in said test cell and also confining said moving air, said cone defining an orifice in substantially a single plane at one end of said cone and defining another orifice in substantially a single plane at the opposite end of said cone and means for adjusting the size of one of said orifices.

19. In combination with an aerodynamic test cell adapted to confine moving air, an adjustable holfow truncated cone located in said test cell and also confining moving air, the smaller end of said truncated cone forming an orifice, means for adjusting said cone to adjust the size of said orifice, and meansfor supporting an object to be tested substantially in the plane of said orifice.

20. In a propeller test cell, means for supporting a propeller and means for rotating said propeller in a substantially fixed position in said cell, means for preventing recirculation of fluid around said propeller comprising, a conduit formed by an overlapping series of leaves hinged to a support, means for adjusting said leaves about said hinges to bring one end of said leaves substantially into the plane of, closely adjacent to and surrounding said propelier, said leaves and said support substantially blocking said test cell except for an area defined by the adjustable orifice end of said leaves.

EDWIN D. EATON. FRANCIS W. CATUDAL.

REFERENCES CITED The .following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,327,543 Funk Jan. 6, 1920 2,094,707 Jones Oct. 5, 1937 FOREIGN PATENTS Number Country Date 375,121 Ger-many June 10, 1921

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