Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D9/00—Stators
  • F01D9/06—Fluid supply conduits to nozzles or the like
  • F01D9/065—Fluid supply or removal conduits traversing the working fluid flow, e.g. for lubrication-, cooling-, or sealing fluids
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
  • F01D11/005—Sealing means between non relatively rotating elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/60—Assembly methods
  • F05D2230/64—Assembly methods using positioning or alignment devices for aligning or centring, e.g. pins
  • F05D2230/642—Assembly methods using positioning or alignment devices for aligning or centring, e.g. pins using maintaining alignment while permitting differential dilatation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• the invention relates to a thin-walled duct penetration sealing grommet, particularly useful for sealing between an opening in a gas turbine engine bypass duct wall and the external surface of a projection extending through the opening to simplify manufacture by eliminating complex joint configurations, while accommodating pressure differential, and relative thermal expansion and contraction.
• the bypass duct of a turbofan gas turbine engine contains a pressurized flow of air between the outer duct wall and the engine core. At several locations along the length and about the circumference of the annular bypass duct, penetrations are necessary for conveying fuel, oil, control cables or compressed air bleed from the compressor to an aircraft cabin, as well as many control and monitoring penetrations for instrumentation, inspection and maintenance.
• the invention provides a bypass duct sealing grommet, for sealing between an opening in a gas turbine engine bypass duct wall and the external surface of a projection extending through the opening.
• the grommet enables an oversized opening for accommodating relative thermal motion and simplifies manufacture.
• the grommet has an annular body with a central aperture adapted to seal against, the external surface of the projection and two flanges defining an external slot about an exterior periphery of the body to contain and seal the bypass duct wall between the flanges.
• Figure 1 is an axial cross-sectional view through a typical turbofan gas turbine engine showing the general arrangement of internal components and in particular the numerous penetrations through the outer annular bypass duct.
• Figure 2 is a radial cross-sectional view through the bypass duct on line 2-2 of Figure 1.
• Figure 3 is a detailed axial cross-sectional view through a prior art penetration through the bypass duct shown along the line 3-3 of Figure 2.
• Figure 4 is an axial cross-sectional view along the line 4-4 of Figure 2 showing another example of the prior art penetration through the bypass duct wall.
• Figure 5 is a partially cut away perspective view of a penetration through the bypass duct wall with a connecting grommet in accordance with the invention.
• Figure 6 is a detailed cross-sectional view through a sealing grommet and adjoining sheet metal walls of the bypass duct and projecting penetration showing the symmetrical trapezoidal cross-sectional profile of the grommet when the bypass wall and a wall of the projection are in a perpendicular orientation.
• Figure 7 shows the deformations of the grommet to accommodate an acute angular orientation.
• Figure 8 shows the deformation of the grommet when relative radial motion is encountered between the bypass wall and a wall of the projection as a result of internal pressure or thermal expansion for example.
• Figure 1 shows an axial cross-section through a turbofan gas turbine engine. It will be understood however that the invention is also applicable to any type of engine with a thin-walled air duct with a penetration (s) requiring sealing. Air intake into the engine passes over fan blades 1 in a fan case 2 and is then split into an outer annular flow through the bypass duct 3 and an inner flow through the low-pressure axial compressor 4 and high-pressure centrifugal compressor 5. Compressed air exits the compressor 5 through a diffuser 6 and is contained within a plenum 7 that surrounds the combustor 8.
• Fuel is supplied to the combustor 8 through fuel tubes 9 which is mixed with air from the plenum 7 when sprayed through nozzles into the combustor 8 as a fuel air mixture that is ignited.
• a portion of the compressed air within the plenum 7 is admitted into the combustor 8 through orifices in the side walls to create a cooling air curtain along the combustor walls or is used for cooling to eventually mix with the hot gases from the combustor and pass over the nozzle guide vane 10 and turbines 11 before exiting the tail of the engine as exhaust .
• Figure 1 illustrates numerous projections and penetrations through the bypass duct 3. Penetrations project through relatively thin sheet metal inner bypass wall 12 and sheet metal or fiber composite outer bypass wall 13. While the accessory gear box 14 has a relatively rigid metal casing that extends through the bypass duct 3, smaller penetrations or projections are also required such as the compressed air bleed valve 15, penetrations for fuel supply lines 16, lubricating oil supply line 17 and igniter 18.
• Figure 2 is a radial cross-sectional view on line 2-2 of Figure 1 showing five penetrating projections 19 extending between the inner bypass wall 12 and outer bypass wall 13 for internally housing various conduits and other services extending between the exterior surface of the engine and the central engine core.
• FIG. 3 shows an example axial cross-sectional detail view through a conventional prior art projection 19 having an outer flange 20 mounted to the outer bypass wall 13 with a resilient gasket 21.
• the projection 19 includes an internal end wall 22 fixed with bolts 23 to the inner bypass wall 12.
• the bypass duct 3 contains an annular flow of fast moving pressurized air which is sealed from the ambient external air with the gasket 21.
• the gasket 21 accommodates radial movements and seals the duct 3.
• the outer bypass wall 13 includes an oversized opening 24 in the thin wall 13 which is reinforced and surrounded by an angle flange 25 riveted to the outer bypass duct wall 13. ⁇ The angle flange 25 retains the gasket 21 and structurally reinforces the bypass duct wall 13 which is weakened as a result of the opening 24.
• the opening 24 is oversized in order to accommodate an assembly tolerance in manufacturing and also to accommodate relative movement due to pressure differential, and thermal expansion and contraction between the projection 19 and the outer bypass duct wall 13.
• FIG. 4 Another example of prior art projection 19 is shown in Figure 4 which has an end wall 22 secured with bolts 23 to a receiving flange in the inner bypass duct 12. To accommodate relative expansion and contraction between the inner bypass wall 12 and outer bypass wall
• bellows 26 extend between a flange 20 of the projection 19 and a mounting plate 27 that is bolted to a supporting plates and riveted to the relatively thin outer bypass duct wall 13.
• Figure 5 is a partially cut away perspective view of a bypass duct sealing grommet 28 that provides a simple low cost means to seal between an opening 24 in the gas turbine engine outer bypass duct wall 13 and the external surface of the projection 19 which extends through the opening 24.
• Figure 6 shows a detailed sectional view through the sealing grommet 28 which comprises an annular body with a central aperture having an interior peripheral surface 29 that is adapted to seal against the external surface of the projection 19.
• a first flange 30 and a second flange 31 define an external slot 32 which extends completely about the exterior periphery of the grommet annular body and is adapted to receive and seal the relatively thin bypass duct wall 13 between the flanges 30 and 31.
• the bypass duct wall 13 is shown as a planar member however it will be appreciated from viewing Figures 1 and 2 that the bypass duct wall 13 actually has a radial curvature and an axial curvature which requires that the grommet 28 has the capacity to deform while maintaining the ability to seal and resist the forces caused by pressure differential on opposing sides of the bypass duct wall 13.
• the grommet 28 must adapt to changes in the orientation of the wall 13 relative to the projection 19 due to the complex curvature of the wall 13 while permitting a degree of relative thermal expansion and contraction and further permitting a degree of manufacturing tolerance in fitting and sealing between the wall 13 and projection 19.
• Figure 7 shows the manner in which the grommet 28 can be deformed to accommodate an angular orientation indicated by angle " ⁇ " whereas Figure 8 illustrates distortion of the grommet 28 to accommodate radial motion of the bypass duct wall 13 relative to the projection 19 which may be caused by pressure differential or expansion and contraction for example.
• the annular body of the grommet 28 has a uniform cross- sectional profile symmetric about the slot 32.
• the grommet 28 may be molded of silicon in an injection molding process or may be extruded as a silicon strip of uniform cross-section through an extrusion process to create an elongate sealing strip of uniform cross-sectional profile.
• a first end of the elongate sealing strip and a mating second end of the strip abut at a joint which may be secured with adhesives or heat resistant • silicon caulking if necessary.
• the uniform cross-sectional profile of the grommet annular body 28 is trapezoidal with a relatively thick collar 33 about the periphery of the projection 19 connecting the first and second flanges 30 and 31.
• the flanges 30 and 31 have a tapered profile which together with the collar 33 provides a variation in resistance to distortion or bending between the relatively flexible outer tip of the flanges 30 and 31 and the stiffer abutting interior peripheral surface 29 which. seals against the projection 19.
• the trapezoidal profile and use ' of the collar 33 increases the tendency of the grommet 28 to jam and interfere with relative movement between the outer bypass duct wall 13 and the projection 19.
• Jamming or distortion creates a resilient or biasing force between the interior peripheral surface 29 and the surface of the projection 19 without the need for embedded springs in the grommet 28.
• the seal created by the distorted grommet 28 maintains the pressure differential between opposite surfaces of the outer bypass duct wall 13 while distortion of the grommet 28 permits a degree of relative movement to accommodate thermal expansion and contraction as well as to accommodate variation in the curvature of the outer bypass duct wall 13 and its angular orientation relative to the projection 19.
• the opening 24 which permits the passage of the projection 19 through the outer bypass wall 13 is oversized in order to permit manufacturing and assembly tolerance and to accommodate relative thermal expansion or contraction or distortion as a result of pressure differential .
• the collar 33, flanges 30 and 31 and opening 24 in the bypass duct wall 13 define an annular clearance gap 34 therebetween.
• the clearance gap 34 permits use of an oversized hole 24 with an acceptable assembly and manufacturing tolerance and ability to accommodate relative movement between the bypass duct wall 13 and the projection 19.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Gasket Seals (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (6)

Families Citing this family (37)

Citations (10)

Family Cites Families (22)

• 2002
  • 2002-12-17 US US10/320,411 patent/US6942452B2/en not_active Expired - Lifetime
• 2003
  • 2003-11-18 DE DE60316604T patent/DE60316604T2/de not_active Expired - Lifetime
  • 2003-11-18 WO PCT/CA2003/001770 patent/WO2004055333A1/en not_active Ceased
  • 2003-11-18 JP JP2004559515A patent/JP2006509946A/ja active Pending
  • 2003-11-18 CA CA2509935A patent/CA2509935C/en not_active Expired - Fee Related
  • 2003-11-18 EP EP03775023A patent/EP1581723B1/en not_active Expired - Lifetime
• 2005
  • 2005-12-08 US US11/178,282 patent/US20060288687A1/en not_active Abandoned

Patent Citations (10)

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