Document
11 11 4,055,041
United States Patent ~191
Adamson et al. [45] Oct. 25, 1977
INTEGRATED GAS TURBINE [561 References Cited ENGINENACELLE U.S. PATENT DOCUMENTS Inventors: Arthur P. Adammn; Donald F.
2,978,209 4/1961 Kerry ..................................... 2 4 / 5 4
Saqisson, both of Cincinnati; Charles 3,269,118 8/1966 Benedict et al. .................... 60/39.31 3,830,058 8/1974 Ainsworth ......................... 60/226 R L. Stotler, Jr., Fairfeld, all of Ohio Primary Examiner-Carlton R. Croyle The United States of America as Assignee: Assistant Examiner-Robert E. Garrett represented by the Administrator of Atforney, Agent, or Firm-R. C. Lampe, Jr.; Norman T.
the National Aeronautics and Space M u d ; Robert Kinberg Administration, Washington, D.C.
WI ABSTRACT
Appl. No.: 628,221 A nacelle for use with a gas turbine engine is provided Filed: Nov. 3, 1975 with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and en- Related U.S. Application Data gine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed Division of Ser. No. 522,108, Nov. 8, 1974.
structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus
Int. CI.2 ........................... M)2C 7/20; F02K 3/04
while the outer surface of the nacelle defines a steam- U . S . C I . ................................. 60/226 R 60/39.3 1; lined envelope for the engine.
24/53 A, 244/54 Field of Search .................. 60/226 R, 262, 39.31; 24/54, 53 A 6 Claims, 5 Drawing Figures ...............
U.S. Patent oct. 25, 1977 Sheet 1 of 4 4,055,041
U.S. Patent oct. 25,1977 Sheet 2 of 4
4,055,04 1
U.S. Patent oct. 25, 1977 Sheet 3 of 4 4,055,04 1
U.S. Patent oct. 25,1977 Sheet 4 of 4
4,055,041
4,055,041
1 2
the responsibility for design of the various components often lies with different manufacturers, the most aero- INTEGRATED GAS TURBINE ENGINE-NACELLE dynamically efficient matching of the two is not This is a division of application Ser. No. 522,108, filed achieved due to overriding individual structural consid- Nov. 8, 1976.
5 erations. An integrated engine-nacelle would optimize engine efficiency, and thereby produce an added bonus BACKGROUND OF THE INVENTION to the performance improvement achievable through This invention relates to gas turbine engines and, the aforementioned anticipated weight reduction. The more Particularly, to engine nacelles for use therewith. problem facing the aircraft engine manufacturer, there- Jet engines for powering aircraft are provided with 10 fore, is to provide a lightweight nacelle integral with nacelles, or other streamlined structures which envelop the engine structure which would improve overall per- the engine to reduce Overall aerodynamic drag and formance through weight reduction and improved improve engine performance. With the advent of large- aerodynamic matching.
diameter gas turbofan engines, the required nacelle structure circumscribing the fan has become increas- 15 SUMMARY O F THE INVENTION ‘ g l Y heavy, thereby increasing aircraft weight and An object of the present invention, therefore, is to reducing its range. The problem is compounded by the provide an integrated gas turbine engine nacelle which fact that since the nacelle is so large and heavy it cannot will reduce overall system weight and thereby improve be supported by the relatively lightweight, present-day gas turbine engines. It is, therefore, hung from the air- 20 aircraft performance.
Another Object Of the present invention is to provide craft pylon as is the engine itself. Accordingly, there is redundancy of structure in the nacelle and engine which a nacelle which will eliminate structural redundancies could be eliminated with a lightweight, integrated en- present in current gas turbine engine-nacelle systems.
Yet another object of the present invention is to pro- gine-nacelle.
~ ~ ~ i ~ ~ l l ~ , in a gas turbofan engine, a fan is provided 25 vide an integrated engine-nacelle which is removable forward of a core engine, the fan being rotatably driven from an aircraft or other vehicle as a single unit.
through shaft connection by the turbine portion of the These and other objects and advantages Will be more engine. The fan Serves to pass a large volume of air clearly understood from the following detailed descrip- around the core engine thereby increasing overall en- tion, the drawings and specific examples, all of which gine thrust. The large volume of air which bypasses the 30 are intended to be typical of rather than in any way core engine (often several times the quantity of air taken limiting the scope of the present invention.
in by the core engine) is routed through an annular fan Briefly stated, the above objects are attained by incor- porating lightweight composite materials in a unique bypass duct.
The fan bypass duct is typically defined, at least in structural relationship whereby the nacelle structure is part, by the core engine and its associated housing (or 35 entirely supported by the engine and wherein the sup- core nacelle) which comprises the inner wall of the porting structure is an integral structure of the gas tur- annulus. The outer wall is defined partially by engine bine engine. As a result of unitizing the engine and structure, but predominantly by the fan nacelle which, nacelle structure, redundancy is eliminated. Further, as Previously noted, is supported by the Pylon Or air- the inner surface of the nacelle may be aerodynamically craft wing. A shroud, or ring, is provided which cir- 40 contoured to provide the outer flow path wall of the cumscribes a limited axial extent Of the fan bypass duct, annular fan bypass duct while the radially outward the shroud being connected through aerodYnamical1y surface of the single thickness nacelle serves as a stream- faired strut means to the core engine. This webbed lined envelope for the engine, The marriage of the na- structure is commonly known as the fan frame. In celle supporting structure with the nacelle itself also tion to the aforementioned struts, a stage of guide vanes 45 provides greater stiffness to the assembly since the two is disposed across the annulus to remove any angular components form one rigid piece.
momentum from the flow exiting the fan to thereby increase axial thrust. The struts provide the load-carry- DESCRIPTION O F THE DRAWINGS ing structure for the shroud while the guide vanes are While the specification concludes with claims partic- loaded only in the aerodynamic sense. Integration of the 50 ularly pointing out and distinctly claiming the subject struts and guide vanes would eliminate redundancy and matter which is regarded as part of the present inven- reduce weight. The ’fan nacelle circumscribes the fan tion, it is believed that the invention will be fully frame and shroud, defining the remainder of the annular description Of the pre- understood from the fan bypass flow path and, also, the outer streamlined envelope for the engine. Redundancy exists, therefore, 55 ferred embodiment which is given in connection with the accompanying drawings9 in which: in both the struts and guide vanes, and in the pylon-to- FIG. 1 is a schematic representation of a gas turbofan engine and nacelle-to-pylon structure.
engine incorporating the subject invention; In addition, aircraft engine removals presently require the “unbuttoning” of the nacelle in order to obtain ac- FIG. 2 represents an enlarged sectional view of a cess to the engine, an often awkward procedure at best 60 Portion of the engine of FIG. 1 , depicting in detail a even when the nacelle is of the bifurcated variety as Podion ofthe Subject invention; typified by US. Pat. No. 3,541,794, Johnston et al, FIG. 3 schematically depicts removal from a typical which is assigned to the same assignee as the present aircraft pylon an engine incorporating the subject in- invention. An integrated engine-nacelle would simplify vention; this procedure and would enable a relatively simple 65 FIG. 4 represents a cross-sectional view of the subject engine disconnect, exterior to the engine, at the pylon. invention taken along line 4-4 of FIG. 1; and Yet another more fundamental problem has existed FIG. 5 is similar to FIG. 4 and shows a cross-sectional through non-integration of the nacelle and engine: since view taken along line 5-5 of FIG. 1 .
4.055,M 1
fluid passing through the engine and the cellular honey- DESCRIPTION O F THE PREFERRED comb core as is well known in the art. Further, an inter- EMBODIMENT mediate skin 64 may be provided to regulate the depth Referring to the drawings wherein like numerals cor- of the honeycomb core 58 in communication with the respond to like elements throughout, reference is first 5 motive fluid in a manner such as to “tune” the system to directed to FIG. 1 wherein an engine depicted gener- discrete acoustic frequencies, as is also known in the art.
ally at 10 embodying the present invention is diagram- Shroud 56 is also shown to include embedded therein matically shown. This engine may be considered as an abradable ,insert 66 circumferentially disposed about comprising generally a core engine 12, a fan assembly the fan blade 15, which provides an abradable surface in 14 including a stage of fan blades 15, and a fan turbine 10 the event of fan blade rub therewith. (Note that the fan 16 which is interconnected to the fan assembly 14 by assembly may include blades of the variable pitch vari- shaft 18. The core engine 12 includes an axial flow ety as well as those of the fixed pitch variety.) Insert 66 compressor 20 having a rotor 22. Air enters inlet 24 and may be provided with slots or grooves 68 which reduce is initially compressed by fan assembly 14. A first por- the abradable surface area (and, therefore, the rubbing tion of this compressed air enters the fan bypass duct 26 I5 force on the blades) and which have also been shown to defined, in part, by core engine 12 and a circumscribing improve fan aerodynamic performance. Additionally, a fan nacelle 28 and discharges through a fan nozzle 3 0 . A containment ring 70 is sandwiched between the abrad- second portion of the compressed air enters inlet 32, is able insert 66 and the honeycomb core 58. Though the further compressed by the axial flow compressor 20 and preferred embodiment includes honeycomb structure as then is discharged to a combustor 34 where fuel is 20 the core structure 58, it is within the scope of the inven- burned to provide high energy combustion gases which tion to provide a shroud of essentially solid structure drive a turbine 36. The turbine 36, in turn, drives the with or without inner and outer skins 60, 62, respec- rotor 22 through a shaft 38 in the usual manner of a gas tively.
turbine engine. The hot gases of combustion then pass A first continuous outer hoop 72 and a similar axially to and drive the fan turbine 16 which, in turn, drives the 25 displaced second outer hoop 74 are shown to circum- fan assembly 14. A propulsive force is thus obtained by scribe the core engine 12, these hoops being affixed to the action of the fan assembly 14 discharging air from skins 60 through 64 by means of flanged braces 76 the fan bypass duct 26 through the fan nozzle 30 and by through 80 and angle braces 82 through 86. It is contem- the discharge of combustion gases from a core engine plated that outer hoops 72 and 74 could be of an integral nozzle 40 defined, in part, by plug 42. The above de- 3 0 singular material thereby obviating the need for braces scription is typical of many present-day gas turbine 76 through 86. Further, though only two outer hoops engines and is not meant to be limiting, as it will become 72,74 are indicated, it is within the scope of the inven- readily apparent from the following description that the tion to provide one or more depending upon particular present invention is capable of application to any gas design criteria.
turbine engine and is not necessarily restricted to gas 35 Referring now to FIGS. 2 and 4 wherein details of the turbine engines of the turbofan varity. The foregoing novel nacelle configuration are more clearly depicted, it description of the operation of the engine depicted in is apparent that the nacelle 28 resembles a wagon wheel FIG. 1 is, therefore, merely meant to be illustrative of with outer hoop 72 circumscribing the core engine 12.
one type of application. Inner hoops 88 and 90 coaxial with outer hoops 72,74 Continuing with the description of the embodiment of 4 0 are disposed within core engine 12 and serve as means the invention as depicted in FIG. 1, it is shown therein to attach the nacelle to the stationary core structure 92, that engine 10 is suspended from a pylon depicted gen- as by bolted connections 94. Inner hoops 88 and 90 also erally at 44 which, in turn, is suspended from and inte- provide structural rigidity to the core engine 12. Dis- gral with, for example, an aircraft wing 4 6 by means of posed radially between the outer hoops and the inner truss structure 4 8 . Pylon 44 is shown to include, and 4 5 hoops are intermediate hoops, herein depicted as two in have disposed within, aircraft accessories depicted gen- number, an axially forward hoop 96 and an axially rear- erally at 50. Critical engine accessories depicted gener- ward one 98. These hoops provide structural rigidity as ally at 50 are enclosed within a pocket 51 of the pylon within a flow splitter 100 (FIG. 2) which serves to split 44 although they are an integral part of the engine hard- the fan motive fluid into bypass portion 26 and core ware as clearly shown in FIG. 3. Appropriate discon- portion entering inlet 32. An additional pair of inner and nects are provided to allow separation of the engine intermediate hoops, 99 and 101, respectively, are pro- from the pylon and aircraft accessories. These accesso- vided to increase structural rigidity of the flow splitter ries are drivingly connected to the core engine 12 by and core engine structure.
means of a shaft 52. Accessories access may be obtaind Web means, such as inner struts 102 and 104, are formed integral with their respective inner and interme- through pylon doors 53 (FIG. 4). The engine 10 is sup- 55 ported on the pylon 44 by means of a thrust mount diate hoops and extend radially therebetween. Simi- assembly 54, which will hereafter be described with larly, additional web means such as outer struts 106 and more particularity. 108 are formed integral with their respective intermedi- Referring now to FIG. 2, the inventive integrated ate and outer hoops, also extending radially therebe- nacelle configuration of FIG. 1 is shown in greater 60 tween. Sheaths 110 and 112 envelop the inner and outer detail. In particular, nacelle 28 is shown to include a struts 102,104 and 106,108, respectively, to provide the shroud means 56 such as a substantially cylindrical struts with aerodynamic contours. It is recognized that shroud, circumscribing fan blades 15 and a portion of the sheaths may be so constructed as to provide airfoil core engine 12, the shroud consisting of a core 58 of the contours possessing characteristics such as camber and honeycomb type sandwiched between an inner skin 60 65 stagger. As depiceted in FIG. 2, the outer struts have and an outer skin 62. Though not necessary, it may be been contoured to serve the function of guide vanes to desirable for acoustic purpose to perforate inner skin 60 properly orient the motive fluid passing therethrough.
to provide fluid communication between the motive The number of inner struts 102,104 and outer struts 106, 4,055,041
5 6
108 need not be equal and, in fact, the sheath outer struts connected to a rear engine mount 154 (FIG. 1) through of FIG. 4 are depicted only schematically since consid- hanger 156. Simple disconnects of a known type at erably more would be required to provide the solidity pylon mounts 140, 144 permit removal of the entire of a typical stage of gui essence, a unitized, integrated engine-nacelle, with pull shaft 52 separating wagon wheel-like nacel 5 from the engine accessories 50 which remain within entirely support the nacelle 28 upon pylon 4 4 . Thus, Applicants have devised a simple preferred that this unitized structure be fabricated.from method of attaching a gas turbine engine to a vehicle lightweight, high strength composite materials. Alter- such as an aircraft which includes the steps of first natively, at least a portion of the structure, such as struts mounting the nacelle to the engine and then mounting 102 through 108 could be formed of bonded, laminated 10 the engine to the vehicle. Conversely, it is foreseeable composite filaments.
that the nacelle could be hung from the aircraft and the The fan nacelle 28 further includes an inlet duct 114, engine then supported by the nacelle.
having a contoured lip 116 (FIG. 11, suspended from It should be obvious to one skilled in the art that shroud 56 and which may be formed integral therewith certain changes can be made to the above-described or removable. A hinge connection 118 may be provided l 5 nacelle without departing from the broad, inventive to permit the inlet duct to be swung out of the way for concepts thereof. For example, in certain applications it improved access to the fan assembly 14 as depicted in may be appropriate to support either the inlet duct 114 phantom in FIG. 3. Alternatively, quick release fasten- or the exhaust duct 120 substantially from the pylon 44 ers of a known type could be employed, or the hinge rather than from the shroud 56. Further, in a turbojet 118 could be disposed elsewhere about the periphery of 2o application wherein there is no fan or bypass duct, it the nacelle. Further, an exhaust duct, generally indi- would be possible to eliminate intermediate rings 96,98 cated at 120, is mounted to the axially rearward end of and interconnect inner ring 88,90 and outer ring 72,74 the shroud 56. FIGS. 2,3 and 5 contemplate, for exam- directly by means of integral spoked structure, the na- ple, an exhaust duct of the hinged type comprising the celle then comprising essentially a core engine nacelle.
addition of a rearward-extending spine 122 formed inte- 25 It is intended that the appended claims cover these and grally with shroud 56 from which nacelle doors 124 and all similar variations in Applicants’ broader inventive 126 are hinged at 128 and 130, respectively. The doors concepts.
are affixed to shroud 56 as by cooperating tongue 132 What we claim is: and groove 134 (FIG. 2) formed thereupon, respec- 1. An integrated propulsion system comprising: tively. Seal 136 prevents the flow of motive fluid 3o a pylon; through the joint formed by cooperating tongue 132 a gas turbofan engine including a core engine for and groove 134. Access to the core engine 12 is pro- rotatably driving a fan stage to pressurize a motive vided as shown in phantom (FIG. 5). Though not fluid, a fan bypass flow annulus generally circum- shown, the core engine 12 may also be provided with a scribing said core engine, a core engine inlet duct nacelle 138 of the hinged or bifurcated variety. 35 communicating with said bypass duct, a flow split- In FIG. 1, it is anticipated that the inlet duct 114 and ter for separating the fan motive fluid into a bypass the exhaust duct 120 be constructed of lightweight, high strength, composite material. Acoustic treatment 135 of portion and a core engine portion, an integral com- the type well known in the art may be applied to the fan posite frame having first and second generally con- centric hoop Of bonded bypass duct outer surface 137 formed in part by the inlet 40 and exhaust ducts, respectively. As depicted in FIG. 1, fabrication interconnected by generally radially acoustic treatment 135, at least in part, is contemplated extending outer struts of composite filament fabri- to be of the full depth acoustic suppression material, cation bonded thereto, said first hoop means sub- such as honeycomb. The use of advanced composite stantially spanning said flow splitter and said sec- materials is recommended such that the acoustic mate- 45 ond hoop means sandwiched between inner and rial can be formed integrally within the duct walls and, outer walls of composite filament fabrication as shown at 135, of itself possess adequate load carrying bonded thereto, said inner wall defining an outer capability. Such load bearing, full depth acoustic struc- aerodynamic contour of the turbofan engine, and ture, when manufactured of composite material, will wherein said inner wall, said outer wall and said provide significant gains in weight reduction. The inner 50 second hoop means form a shroud entirely SUP- fan nacelle surface 137 (which forms the fan bypass duct ported in spacial relationship with said first hoop outer flow path) and the nacelle outer surface 139 may means through said outer struts; and be aerodynamically contoured to provide the most effi- mounting means connecting said first hoop means to cient configuration. said pylon.
2. The propulsion system of claim 1 further compris- FIG. 3 depicts schematically the entire integrated 5 5 nacelle 28 and its removal from a typical aircraft pylon ing third hoop means of bonded filament fabrication 4 4 . Truss structure 48 includes a forward pylon mount disposed within and connected to said core engine, and 140 which supports the engine, in part, by pin or bolt further connected to said first hoop means by a plurality connection with engine hanger 142 while primary of inner struts of composite filament fabrication, said thrust support is obtained through thrust mount assem- 60 inner struts supporting said core engine and flow split- bly 54. Rear pylon mount 144 is operatively connected ter in predetermined spacial relationship.
to a forward engine mount 146 by means of thrust rod 3. The propulsion system of claim 1 wherein said 148, engine mount 146 being formed integrally with mounting means includes: a forward pylon mount at- intermediate hoop 98. A similar engine mount, not tached to an engine hanger associated with said second shown, is disposed on the other side of the engine and is 65 hoop means; and connected to rear pylon mount 146 by thrust rod 150. a thrust mount comprising a rear pylon mount opera- Pin 152 (FIG. 2) facilitates connection of engine mount tively connected to a forward engine mount asso- 146 and thrust rod 148. Rear pylon mount 144 is further ciated with the first hoop means and further con-
4,055,041
I 8
said shaft means is disconnected from said accessories nected to a rear engine mount associated with the when said turbofan engine is dismounted from said core engine.
pylon and connected to said accessories when said 4. The propulsion system of claim 3 wherein said rear turbofan engine is mounted on said pylon.
pylon mount is operatively connected through a pair of 5 6. The propulsion system of claim 3 further including: thrust rods to two circumferentially spaced forward engine accessories and wherein said engine accesso- engine mounts attached to the first hoop means.
ries are mounted upon said turbofan engine outer 5. The propulsion system of claim 3 further including: wall and are disposed within a pocket formed engine accessories driven by said core engine; and within said pylon when said turbofan engine is pull shaft means for operatively connecting said ac- 10 mounted thereon, and when said turbofan engine is cessories and said core engine; wherein dismounted from said pylon, said accessories are said engine accessories are substantially mounted removed contemporaneous therewith.
* * * * *
within a pocket in the pylon; and 5 5