US2846023A - Protective device for jet engines - Google Patents

Description

Aug. 5, 1958 v. MILLMAN PROTECTIVE DEVICE FOR JET ENGINES Filed April 19, less 2 Sheets-Sheet 1 FIG. 2

INVENTOR. VICTOR M/LLMA/V A T TOR/VE' Y 1958 v. MILLMAN 2,846,023

, PROTECTIVE DEVICE FOR JET ENGINES 2 Sheets-Sheet 2 Filed April 19, 1956 24 FIG. 4

28 INVENTOR.

VICTOR MlLLMA/V 21 e Bgxpwbcu1 ATTORNEY PnoTEcrrvE DEVICE FOR JET ENGINES Victor Millman, San Diego, Caliii, assignor to General Dynamics Corporation, San Diego, Calif., a corporation of Delaware Application April 19, 1956, Serial No. 579,243 7 Claims. (Cl. 183-51) The present invention relates to protective screen devices and more particularly, an improved form of screen device for use in connection with jet engines for entrapment of foreign matter at the air inlet of an engine.

Prior to actual flight of an airplane, certain adjustments and checks must be made by ground crew personnel which necessitates operating the engines while the airplane remains on the ground. Suction created by a jet engine is of such force as to pick up debris of foreign material in the immediate vicinity of the engine air scoop and unless restrained such debris is carried into the internal mechanism of the engine. Due to the extreme high velocity of the engine, small solid particles on the ground such as pebbles, stones, nuts, bolts and the like, sucked into the engine have caused either considerable damage to, or complete destruction of, the engine. In an attempt to avoid damage to an engine from foreign matter entering the air inlet, ground testing areas must be swept at frequent intervals in an attempt to rid the area of material which might prove destructive. Even though the ground is swept certain objects may be missed or may be dropped inadvertently in the area after a sweeping.

To prevent foreign matter entering the air inlet of the engine protective screens have been employed. However in the use of a protective screen with the air scoop of the engine, it has been found that a screen, to serve effectively the desired purpose, must satisfy certain conditions. The screen must be so constructed that it will not restrict or impede the volumetric air flow to a degree which would result in overheating and subsequent damaging of the engine. Also, the screen must have sufficient strength to resist inward collapse. A further consideration preferably requires the major portion of the intake air to be drawn from above the engine rather than from the front and sides. The screen should be compact, light, and, since it is required only while the engine is being ground tested, readily detachable from the engine air scoop before flight of the airplane.

It is, therefore, the principal object of this invention to provide an improved form of screen having the desirable characteristics, as above enumerated, and which serves etfectively to filter deleterious foreign material from the air entering the air inlet of a jet engine.

Another object of this invention is to provide a protective screen of improved construction, being in the form of a cage with a trap element included therewithin which acts to arrest and collect foreign particles irom the air entering the engine.

Another object of this invention is to provide a protective screen of the type above embodying quick dis connect means to permit ready detachment of the screen from the engine.

Another object of this invention is to provide a proteetive screen filter device for a jet engine which is simple and durable, economical to manufacture, and efficient in operation.

Other objects and features of the present invention will States Patent 9 2,846,923- Patented Aug. 5, 1958 be readily apparent to those skilled in the art from the following specification and appended drawings wherein is illustrated a preferred form of the invention, and in which:

Figure 1 is a perspective view of a screen device embodying the present invention and shown in operative position on a typical jet airplane.

Figure 2 is an enlarged plan view of the screen shown in Figure 1 with a portion cut away to facilitate illustration.

Figure 3 is a side elevational view with a portion cut away to show the debris trap construction, and

Figure 4 is an end view of the present screen device.

Referring now to the drawings, a protective screen or filtering device constructed in accordance with the present invention is indicated therein in its entirety by the numeral 1i), and, in Figure l, is shown operatively positioned upon an air inlet scoop 11 of a typical jet powered airplane 12.

Screen device 10 involves a body structure defining a chamber which body structure is of generally box-like shape, having a substantially segmental outline in side elevation, and which forms, in effect a cage.

Screen device 10 embodies a framework 13 suitably formed into the desired configuration of device 10 and made of a plurality of sections or lengths 14, of angle iron, or of any other suitable metal, the various sections being appropriately connected at their ends to one an other, as by welding, to effect a rigid structure. Afiixed to framework 13 are a top member or panel 15, a pair of side members 16 of generally segmental outline, and a member 17, of arcuate form, which extends from top member 15 to form an end and the bottom of the cage; top member 15, as shown, may slope downwardly from its joinder at the upper edge of wall member 17 to its joinder with the rear end of screen device 10. Member 17 and side members 16 are formed of two layers 18 and 19 of screen mesh, the outer layer 18 being of relatively fine mesh having approximately one-sixteenth inch square openings, and the inner or backing layer 19 being of coarser mesh having approximately onehalf square openings. Inner layer 19 serves to reinforce fine mesh layer 18 and adds strength and rigidity to the structure. The outer and inner screen layers 18 and 19 which comprise side members 16 and arcuate member 17 are suitably aflixed, as by welding, to tensioning frames 21 conveniently formed of flat strips of metal arranged in the desired outline for members 16 and 17.

Top members 15 preferably is formed of a coarse screen 22, having approximately one-half inch square openings, which is carried by a tensioning frame 23 made of flat metallic strips.

Arcuate end and bottom member 17 and side members 16 are atfixed to framework 13 of device 10 as by welding, or in any other well-known manner. For convenience, top member 15 is removably secured to framework 13 by suitable fasteners such as screws, in order to permit ready access to within device 10 for cleaning purposes.

The rearward end 24 of screen device 141 confronts the opening of the air inlet scoop 11 and has an opening formed therein which conforms in outline to the outline of the scoop opening. Figure 4 illustrates the configuration of a typical opening 25 in end 24 which it is to be assumed is the same as the outline of the opening of the air inlet scoop with which the present screen device It is to be employed. In constructing opening 25 a plurality of appropriately shaped sections 26 of metallic tubing, or angle iron, is suitably connected together, as by welding, into a frame 2'7 of the required configuration. This frame 27 is conveniently afiixed to framework 13 in end 24 by tubular elements or braces 28 having Welded connections to the frame 27 and framework 13. Included at end 24 are two layers 18 and 19 of screen mesh identical to the layers 18 and 19 of side members 16 and arcuate member 17, layer 18 being of relatively fine mesh and layer 19 being coarser and serving to reinforce the first layer. It is understood, of course, that layers 18 and 19 are applied in surrounding relation to opening 25 and offer no obstruction to such opening.

Located at end 24 are a plurality of clip members 31 formed of metal having some resiliency such as spring steel which are rigidly secured to frame 27 defining opening 25 by nut and bolt assemblies 32, or, if desired, these clip members may be riveted in place. Clip members 31 project rearwardly from end 24 and are adapted to fit with resilient pressure about the edge contour of air inlet scoop 11 to position screen device properly relative to the scoop. To maintain device 10 on scoop 11 against inadvertent dislodgment the uppermost of the clips 31 may be secured to the scoop by a temporary fastener such as a screw.

Within the chamber of cage-like construction of device 10 formed by the screen-covered framework 13 is positioned a generally rectangular trap or barrier member 33. Trap 33 is located upon the bottom of device 10 near the rearward wall 24 and extends upwardly from the bottom and is forwardly inclined. Trap 33 extends transversely across the bottom of device 10 from side member to side member thereof and is formed of a forward layer 34 of relatively fine mesh screen, similar to outer screen layer 18 above described, backed by a coarse screen layer 35, similar to inner layer 19 hereinbefore mentioned. These screen layers are suitably secured to a frame 36 formed by side angle members 37 rigidly connected in spaced apart relation to framework 13 and a transverse interconnecting angle member 33 afiixed to the upper ends of side members 37. Brace members 41 interconnected between framework 13 and frame 36 may be provided for support of frame 36.

As has been described, arcuate member 17 and side members 16, in their construction, include two screen layers 18 and 19, with the first being of finer mesh than the second, while top member includes but one screen layer which is of coarse mesh. By reason of this screen arrangement, it is apparent that air will more readily enter through top member 15 since less obstruction is afforded to the air. Thus, the major volume of air which is supplied to air inlet scoop 11 enters device 10 by way of top member 15. It is necessary that top member 15 be more open than the sides or bottom of device 10 to assure that a sufficient volume of air is provided to the engine. Obviously, if not enough air were provided the engine would overheat and be damaged.

Screen device 10 is made of suflicient height that the more open top member 15 will be located above the uppermost edge of the air inlet scoop 11 so that the major volume of inlet air supplied to the scoop is taken into device 10 from above the scoop and is directed downwardly by arcuate wall member 17 to the scoop. The purpose of arcuate wall member 17 will be hereinafter more fully described.

In operation, screen device 10 is positioned upon the air inlet scoop of the jet engine to be serviced with its opening aligned with the opening of the scoop. With the jet engine running, some inlet air is drawn through all the screened surfaces of device 10 but the major portion is supplied from above through top member 15. The arcuate form of wall member 17 causes the air entering from top member 15 to move in such fashion that the solid objects which may have been carried in are caused to gravitate to the bottom and to pass along the arcuate Wall member until arrested by trap 33; in effect, device 10 acts as a centrifuge. Trap 33 is of suffieient height that it will effectively bar passage of foreign material to the air inlet scoop, but will not offer any appreciable barrier or disturbance to the flow of air to the scoop. The etfective height of trap 33 can be readily determined by test methods employing suction devices or the like.

By enclosing the sides and bottom of device 10 with a fine mesh screen, as described, it has been found that objects of a size harmful to the engine will be effectively filtered from such inlet air as enters through the fine mesh screen. Also by causing the major volume of the air used by the engine to enter from the top of device 10 it renders it more difiicult for objects of harmful size to be carried into device 10, and should harmful objects e carried up, over and pass through the screen of top member 15 into device 10 the arcuate wall member 17 will direct these objects against trap 33 to be arrested thereby. As stated above, the present screen device 10 is not intended to be a permanent attachment to the jet engine. After the necessary tests and checks have been made screen device 10 is removed by withdrawing the attaching screw just prior to take-off.

It is understood that the present invention is not to be limited to screen mesh having openings of the size described, and that the screens which have been described are to be considered only as examples.

From the foregoing it will be seen that there has been provided a screen device which effectively protects the jet engine from foreign harmful objects while permitting the entrance of sufficient volume of air for proper operation of the engine. The present invention also serves as a safety device in another respect in that, by reason of its sturdy construction, it offers protection to personnel who working in the area of the jet engine might accidentally be drawn by the air toward the engine.

While a certain preferred embodiment of the invention has been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims:

What I claim is:

l. A protective device for use with the air inlet of a jet engine for filtering foreign material from air entering said air inlet comprising a body structure defining a chamber and having its wall members formed of screen for the passage of air, including among its wall members a top wall member and a rear wall member, the screen of said top wall member being of coarser mesh than the screen afforded the other wall members for the more ready passage of air therethrough into the body structure, said rear wall member having an opening therein adapted for alignment with the opening of said air inlet, and one of said other wall members extending downwardly and rearwardly from said top wall member to said rear wall member and being of generally arcuate configuration.

2. A protective device for use with an air inlet of a jet engine for filtering foreign material from the air entering said air inlet, said device comprising a closed wall screened cage, said walls of said cage including a top wall covered with screen of coarser mesh than the other screened walls for the more ready passage of air into said cage, another of said walls having an opening therein adapted to confront the opening of said air inlet, and screened trap means within said cage arranged to partially project into the intake air stream for arresting and collecting foreign particles from the air passing through said cage.

3. A protective device for use with the air inlet of a jet engine for filtering foreign material from air entering said air inlet comprising a body structure defining a chamber and having its wall members formed of screen for the passage of air, the screen of at least one of said wall members being of coarser mesh than the screen afforded the other wall members for the more ready passage of air therethrough into said chamber, said lastmentioned wall member being arranged to be positioned above the opening to said air inlet, one of said wall members having an opening therein adapted for alignment with the opening of said air inlet, and screened trap means within said chamber supported to project partially into the intake air stream for arresting and collecting foreign particles from the air passing through said chamber.

4. A protective device for use with the air inlet of a jet engine for filtering foreign material from air entering said air inlet comprising a body structure defining a chamber and having its wall members formed of screen for the passage of air, including among its wall members a top wall member and a rear wall member, the screen of said top wall member being of coarser mesh than the screen afiorded the other wall members for the more ready passage of air therethrough into said chamber, said rear wall member having an opening therein adapted for alignment with the opening of said air inlet, one of said other wall members extending downwardly and rearwardly from said top wall member to said rear wall member and being of generally arcuate configuration, and screened trap means within said chamber supported to project partially into the intake air stream for arresting and collecting foreign particles from the air passing through said chamber.

5. A protective device for use with the air inlet of a jet engine for filtering foreign material from air entering said air inlet comprising a body structure defining a chamber and having its wall members formed of screen for the passage of air, including among its wall members a top wall member arranged to be positioned above the opening to said air inlet and a rear wall member, the screen of said top wall member being of coarser mesh than the screen afforded the other wall members for the more ready passage of air therethrough into said chamber, said rear wall member having an opening therein adapted to be positioned at the opening of said air inlet, one of said other wall members extending downwardly and rearwardly from said top wall member to said rear wall member and being of generally arcuate configuration, and a barrier member disposed within said chamber of said body structure, projecting partially into the intake air stream and extending transversely across said last-mentioned wall member for arresting and collecting foreign particles from the air passing through said chamber, said barrier member comprising screening and bracing means for holding said screening in position.

6. A protective device for use with an air inlet of a jet engine for filtering foreign material from the air entering said air inlet, said device comprising a closed wall screened cage, the top wall of said cage arranged to be positioned above the opening to said air inlet and being covered with screen of coarser mesh than the other screened walls for the more ready passage of air into said cage, the rear wall of said cage having an opening therein adapted to confront the opening of said air inlet, and trap means disposed on the bottom wall of said cage and adjacent the rear wall thereof and projecting partially into the intake air stream for arresting and collecting foreign particles from the air passing through said cage, said trap means comprising screen means extending transversely across said bottom wall, and bracing means for holding said screen means in position.

7. A protective device for use with the air inlet of a jet engine for filtering foreign material from air entering said air inlet comprising a body structure defining a chamber and having its wall members formed of screen for the passage of air, including among its wall members a top wall member arranged to be positioned above the opening to said air inlet and a rear wall member, the screen of said top wall member being of coarser mesh than the screen afforded the other wall members for the more ready passage of air therethrough into said chamber, said rear wall member having an opening therein adapted for alignment with the opening of said air inlet, one of said other wall members extending downwardly and rearwardly from said top wall member to said rear wall member and being of generally arcuate configuration, trap means within said chamber for arresting and collecting foreign particles from the air entering said chamber, said trap means comprising a screen positioned adjacent said rear wall, transversely across said wall of arcuate configuration and angularly inclined to said rear wall and projecting partially into the inlet air stream.

References Cited in the file of this patent UNITED STATES PATENTS 1,261,554 Knauff Apr. 2, 1918 1,619,954 Olmstead et a1. Mar. 8, 1927 2,399,186 Hunter Apr. 30, 1946 2,500,268 Adams Mar. 14, 1950 2,660,317 Mork et al. Nov. 24, 1953 FOREIGN PATENTS 59,292 Denmark Dec. 15, 1941 124,101 Australia Apr. 21, 1947

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