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
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/14—Form or construction
  • F01D5/20—Specially-shaped blade tips to seal space between tips and stator
• • 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
  • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
  • F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
  • F01D11/122—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part with erodable or abradable material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/08—Sealings
  • F04D29/16—Sealings between pressure and suction sides
  • F04D29/161—Sealings between pressure and suction sides especially adapted for elastic fluid pumps
  • F04D29/164—Sealings between pressure and suction sides especially adapted for elastic fluid pumps of an axial flow wheel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/26—Rotors specially for elastic fluids
  • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
  • F04D29/321—Rotors specially for elastic fluids for axial flow pumps for axial flow compressors
  • F04D29/324—Blades
• • 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
  • F05D2220/00—Application
  • F05D2220/30—Application in turbines
  • F05D2220/36—Application in turbines specially adapted for the fan of turbofan engines
• • 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

• This invention relates generally to gas turbine engines, and more specifically to methods and apparatus to reduce lip rub loads induced in rotor blades j ( i ( iO2j
• gas turbine engines typieaik include a casing, a fan rotor assembh . low and high pressure compressors, a eomb ⁇ stor, and at least one turbine.
• the compressors compress air which is channeled to the eombustor where it is mixed with fuel The mixture is then ityiited for generation hot combustion eases
• the combustion gases are channeled to the turbme ⁇ s) which extracts energy from the combustion gases for powering the compressor(s). as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator
• Some known fan and compressor assemblies include a casing that encloses a rotor having a plural Uy of rotor blades Under certain engine operating conditions, the rotor blades may be subject to blade tip rub ev ents that induce radial and tangential loads sn the Made airfoils. Excessne rub loads nmv facilitate damage in the blade due to vibrator ⁇ and fatigue conditions. Excessn e rub loads from the blade tubs may also facilitate secondary damage that includes damage to non-adjacent blades and the casing. Excess: ⁇ e fan blade rubs max' exert large aib loads on the rotating disks and bearings if the blade plows through the fan case abradable system.
• an airfoil comprises a tip-grinder located on a tip portion, said tip-grinder capable of removing a portion of an abradable material during a tip rub foots?
• an airfoil comprises a tip-rake located on at least a part of the tip portion extending between satd first and second sidewalls, said tip-rake having a rake-profile that facilitates reducing loading induced to said airfoil during tip rubs.
• a blade assembly comprises an airfoil and a metal leading edge (MLE) coupled to at least a portion of said airfbiL said MLE having a tip-cutter capable of removing a portion of an abradable material during a tip rub.
• MLE metal leading edge
• a falisk comprises a plurality of airfoils extending from a hub and a tip-colter .located on at least one airfoil, said tip-cutler capable of removing a portion of an abradable materia! during a tip rub.
• a biisk comprises a plurality of airfoils extending from a hub and a tip-grinder located on at least one airfoil, said tip-grinder capable of removing a portion of an abradable material during a tip rub.
• a method for reducing tip rub loads in an airfoil comprising the steps of selecting a location of contact between the airfoil and a static structure; selecting a location on the airfoil for incorporating a tip-cutter; selecting a cutter-profile for the tip-cutter; and incorporating lhe tip-cutler on the selected location on lhe airfoil such thai tip-cutter is capable of removing a portion of lhe static structure during a tip rub such thai tip rub loads are facilitated to be reduced.
• a method for reducing tip rub loads in an airfoil comprises providing a tip-grinder located on a lip portion, said tip-grinder capable of removing a portion of an abradable material during a tip rub,
• a method for reducing tip rub loads in an airfoil comprises providing a lip-rake located on at least a part of the tip portion, said tip-rake having a rake-prof ⁇ le that facilitates reducing loading induced to said airfoil during tip rubs,
• a method for assembling a rotor assembly comprises the steps of providing a blade assembly including an airfoil and a metal leading edge (MLE); removing material from a portion of the MLE to form a tip-cutter; and coupling the blade assembly to a rotor hub such that during tip rubs lhe tip-cutter machines an abradable material to facilitate reducing radial loading induced to the blade during tip rubs.
• MLE metal leading edge
• FlO. 2 is a perspective view 1 of a rotor blade comprising an airfoil according to an exemplary embodiment of the present invention.
• FlG. 3 is a perspective view of the tip portion of the airfoil shown in FlG. 2.
• FlG, 4 is a cross-sectional illustration of the tip portion of the airfoil shown in FIG. 2 positioned within lhe casing of lhe gas turbine engine shown in FlG.
• FIG 6 is a Ikw cbaii showing the steps of a method of i educing tip aib loading
• FIG. 1 is a schematic initiation of an exemplars engine assenibh 10 haung an exemplars embodiment of the present im ention of a rotoi blade 15 hav ing a tip portion 60 that facilitates reducing rub loads induced to the iotor blade 15 when a tip rub occurs betw een the blade tip and the casing 1 ?
• Coie gas tiwbme engine 16 includes a high-pressure compiessoi 22.
• Booster compressor 14 includes a pluralm of rotor blades 40 that extend substantially tadialh outw ard from a iotor dtsl 20 coupled to a first dm e shaft 31 fcngme assemble 10 has an intake side 28 and an exhaust side 30 Compressor 22 and high-pressure turbine IH are coupled together b ⁇ a second dm e shaft 29
• Atr enters engine IO through intake side 2H and Oows through fan assembh 13 and compressed air is supplied fsom fan assembh 13 to booster compressor 14 and high pressure compressor 22
• the pluraht) of rotoi blades 40 compress the air and deln er the compressed mr to core gas turbine engine 16 ⁇ nOow is further compressed b> the high-pressure compressor 22 and is deliv ered to combustor 24 HoI gases Horn combustor 24 dme rotating tuibmes 18 and 26 and exit Kas turbine entune IO thiouah exhaust side 30
• the present imention ⁇ des an exemplars apparatus and method for reducing rub loads induced in an airfoil, such as, for example, in a rotor blade I 4 * and rotor assembh 13 used m a gas turbine engine 10
• Figure 2 is a perspective ⁇ sew of a iotor blade 15 used m the fan or cornpressot section of the engine J O
• the rotor blade shown as numeral item 1 ⁇ is a fan rotor blade and rotor Made show n a.s numeial item 40 is a c ⁇ ipressoi section rotoi blade
• the present invention is described herein with respect to fan and compressor rotor blades, the present invention is not limited Io such components, and applies to integrally bladed disks ⁇ "BUSKS' " ) that have integral airfoils, and turbine rotors 18.
• a rotor blade 15 is provided that includes an airfoil 42 having a first sidewall 44 (alternatively referred to herein as “Pressure Side” and “Concave Side”), a second sidewall 46 (alternatively referred to herein as “Suction Side “ ' and “Convex Side”), a root portion 54 and a tip portion 60.
• Rotor blade 15 includes an airfoil 42, a platform portion 55. and an integral dovetail portion 43 that is used for mounting rotor blade 15 to rotor hub 21.
• Airfoil portion 42 includes a first sidewall 44 and a second sidewall 46.
• first sidewall 44 is substantially concave and defines a pressure side of rotor blade
• second sidewall 46 is substantially convex and defines a suction side of rotor blade 15.
• Sidewa ⁇ ls 44 and 4(S) are joined together at a leading edge 48 and at an axi ally-spaced trailing edge 50. Trailing edge 50 is spaced chord-wise and downstream from leading edge 48.
• Tip portion 60 is defined between sidewalls 44 and 46 and includes a lip surface 62, a concave edge 64. and a convex edge 66.
• Dovetail portion 43 includes a platform 55 positioned at root portion 54 and extending circumferential! ⁇ outward from first aid second sidewalis 44 aid 46, respectively.
• dovetail 43 is positioned substantially axially adjacent root portion 54
• dovetail 43 may be positioned substantially citcuniferentially adjacent root portion 54
• Rotor blades 15, 40 may have any conventional form, with or without dovetail 43 or platform 55.
• the airfoil 42 of rotor blades 1.5, 40 may be formed integrally with a rotor hub 21 or disk (alternatively referred to herein as a blisk). In a bhsk-type configuration, the rotor blades 15. 40 do not include dovetail 43 and platform 55.
• an abradable material 32 is coupled to a casing 1.7 thai extends circuniferentially around a longitudinal axis 12.
• Platforms 55 of rotor blades 40 define an inner boundary of a flow-path 35 extending through booster compressor 14.
• the inner boundary may be defined by a rotor disk 2 S (shown in Figure I )- ' ⁇ e casing 17 and abradable material 32 define a radially outer boundary of the (low-path 35 As shown in FIG.
• abradable material 32 is spaced a distance Di and D2 from each rolor blade tip portion 60 such that a clearance gap 33 is defined between materia! 32 and airfoil 42.
• abradable material 32 is spaced a distance D2 from convex edge 66 and a distance Dl from concave edge 64. Distances Dl and D2 are selected to facilitate preventing tip rubs between rotor blades J 5. 40 and abradable material 32 during engine operation.
• the inner and outer boundaries of fiow-path are nol parallel and stacking axis 80 is not required to be perpendicular to outer flow path boundary.
• rotor disk 20 (and rotor bub 21 ) rotates within an orbiting diameter that is substantially centered about longitudinal axis 12. Accordingly, rotor blades 15. 40 rotate about longitudinal axis 12 such thai clearance gap 33 (see FIG. 4) is substantially maintained and. more specifically, such that tip portion 60 remains a distance Dl from abradable material 32. with the exception of minor variations due to small engine 10 imbalances Clearance gap 33 is also sized to facilitate reducing an amount of air i.e., tip spillage. that may be channeled past tip portion 60 during engine operation.
• blades 15 may deflect such that tip portion 60 may rub abradable material 32.
• some portions of the airfoil tip may be jammed into abradable material 32. such that radial and axial loads axe induced to rotor blades. Frequent tip rubs of this kind may increase the radial loads and blade vibrations.
• Such loading and vibratory stresses may increase and perpetuate the dynamic stresses of conventional airfoils, which may subject the conventional blades to material fatigue. Over time, continued operation with material fatigue may cause blade cracking and/or shorten the useful life of the rotor blades.
• FlO. 2 illustrates an exemplary fan rotor blade 15 according to one embodiment of the present invention
• FiG. 3 is a perspective view of the tip portion of the airfoil 42 of the rotor blade 15.
• FiG. 4 is a cross-sectional illustration of the tip portion of the airfoil 42 of the rotor blade shown in FiG. 2 positioned within the casing 1 7 of the gas turbine engine 10 shown in FIG. 1.
• rotor blade 15 has a tip portion 60 that facilitates reducing radial loading induced to blade 15 if lip rubs occur during engine operation.
• certain features are provided near the airfoil tip 61 aid leading edge 48 regions that facilitate reducing the rub loads that are generated when airfoil tip rubs against the abradable material 32 under certain operating conditions. Specifically, these features reduce the rub loads by re.niovi.ng a portion of the abradable materia! 32 by machining.
• One such feature shown in the exemplary embodiments herein (See FIG. 2). is a lip-cutter K)O that is located near the lip portion 60. In the exemplars- embodiment shown in FlO. 2.
• the tip-cutter 100 is located near the leading edge 48 near the tip 6 L on the " pressure Side ' ' (first sidewail 44) of the airfoil 42.
• the tip-cutter 1.00 has a cutter-profile 102 having geometric features (See FiG. 4) that are capable of removing a portion of the abradable material 32 by machining during a tip rub.
• the exemplar ⁇ ' cutter-profile 102. shown in FlG 4. comprises a cutter-angle 104 located at the leading edge 48 at the airfoil tip 61
• the cutter-angle 104 is an angle between the leading edge 48 and a flat portion 108 at the blade tip 6 L as shown in FlO. 4.
• the cutter-angle 104 is selected such that it promotes the machining and removal of the abradable material 32 during a lip rub event.
• the cutter-angle 104 may have a value between about 1 degree and 10 degrees. hi a preferred embodiment, the cutter-angle 104 has a value between about 2 degrees and about 5 degrees.
• the cutter-profile 102 shown in FIG. 4 further comprises an arcuate recess 106 that extends into the airfoil to a certain depth "B * (See FTG. 4). In a preferred embodiment, lhe depth £ "B " has a value of about 0.005 inches. In other embodiments, the depth "B" may have a value of up to about (1050 inches.
• the cutler profile 102 near the tip M extends in a span- wise direction along a portion of the leading edge 48, as shown in FlG. 2.
• the cutter profile 102 also extends in a chordwise direction along a portion of the airfoil 42 from the leading edge 48 towards the trailing edge 50 such that the depth "B " ' and the cutter-angle 108 gradually reduce to zero so as to blend smoothly with the airfoil concave side 44 to promote smooth airflow in the airfoil 42.
• the airfoil 42 has a tip-grinder S 20 located on the tip portion 60. such as. for example, near the leading edge 48. as shown in FlG. 2.
• the tip-grinder J 20 comprises an abrasiv e material applied to the airfoil tip that serves as a cutting agent for an abradable material 32 located in the casing i 7.
• the tip-g ⁇ nder abradable material may be regular or irregular in shape and may have sharp edges that are less than .010 inches in radius.
• the tip-grinder 120 is made from a suitable material that is capable of removing a portion of an abradable materia! 32 during a tip nib.
• the tip-grinder 120 is made from a ceramic, metallic or intermetallic material having a composition comprising of embedded abrasive materia!. In the case of metallic and intermetaliic particles the hardness of the material would be in excess of Vickers 750 (g/mra ⁇ 2).
• Known abrasive materials may be used in the tip-grinder 120.
• Preferred known abrasive materials used for the tip-grinder 120 include Aluminum Oxide, Silicon Carbide, CBN or Diamond,
• the iip-grinderl20 may be bonded to the airfoil 42 using known methods such as brazing and welding.
• the tip- grinder 1.20 is banded to the airfoil 42 by brazing.
• the tip-grinder 120 may be bonded or applied to the airfoil 42 by thermal spray or using a known bonding adhesive.
• the lip-grinder 120 is shown in FlO. 4 as being located near the leading edge 48 tip. in alternative embodiments, the tip-grinder 120 may be located at the blade tip near trailing edge 50, or other suitable locations on the tip 61.
• the present invention comprises a tip-rake 1 10 (See FlG. 4) extending between the first and second sidewalls 44, 46, located on at least a part of the tip portion 60.
• the tip-rake il O has a rake-profile 1 12 that facilitates reducing loading induced to the airfoil 42 during lip tubs, ⁇ n the exemplary embodiment shown in FiO. 4, the rake-profile 1 1.2 has a rake angle 1 14 ("A "" ⁇ with respect to a plane 82 that is substantially perpendicular to a stacking axis 80 of the airfoil 42.
• the stacking axis 80 is an axis that extends through blade 15 in a span-wise direction from root portion 54 to tip portion 60.
• the tip-rake 1 10 may have a rake angle 1 14 between about 2 degrees and about 15 degrees.
• the tip-rake I I O has a rake angle 114 between about 3 degrees and about 5 degrees.
• tip surface 62 extends obliquely between airfoil sidewaSls 44 and 46. More specifically, tip surface 62 is oriented at a rake angle A.
• the tip surface 62 has a rake- profile 1 12 defined by rake angle A.
• the orientation of the rake tip surface 62 as defined by the rake-profile 1 12 causes the clearance gap 33 to be non-uniform across blade tip portion 60.
• a height D2 of clearance gap 33 at convex edge 66 is greater than a height Dl of clearance gap 33 at concave edge 64 (see FJCJS. 2 and 4).
• surface 62 having a rake-profile 1 12 is formed via a raking process.
• surface 62 may be flat having a substantially constant rake angle A using any other known fabricating process, including but not limited to. a machining process.
• a conventional blade may be modified to create the blade 15 to include tip portion 60 as described herein.
• a tip-cutter 100 is formed by machining, or other known methods, near the tip of a blade as described herein.
• a tip- grinder 120 is coupled to an existing blade as described herein and shown in F ⁇ GS. 2- 5. Additionally and optionally, excess blade material from an existing blade tip portion 60 is removed via a raking process to form tip portion 60 with a corresponding rale-profile 1 12 and rake angle A that facilitates prevention of convex edge 66 contact with abradabie materia! 32 during a tip rub.
• the rake angle A may have a value between about 5 degrees and about 15 degrees. More specifically, in a preferred embodiment, the rake angle A has a value between about 3 degrees and about 5 degrees, ⁇ n alternative embodiments, blade 15 $x formed with t ⁇ portion 60 having rake-profile 1 12 and rake angle A, and lip-cutter 100 via a known processes. such lhat tip portion 60 is formed with a desired rake-profile 1 12, and cutler-profile 102. and optionally, tip-grinder i 12 is added at the lip 6i .
• the rotor disk 20 rotates within an orbiting diameter that is substantially centered about longitudinal axis 12. Accordingly, rotor blades 15, 40 rotate about longitudinal axis 12. and a sufficient clearance gap 33 is maintained between rotor blade tip portion 60 and abradabie material 32. In the event blade 15 or 40 is deflected, tip portion 60 may inadvertently Rib abradabie material 32. As shown in FIGS. 2 and 4, because tip portion 60 is oriented at rake angie A, during a tip rub, concave edge 64 is closer to the abradabie materia! 32, rather than convex edge 66.
• the tip-g ⁇ nder 120 if present, first contacts the abradable material 32 and machines away a portion of the abradabie material 32.
• the tip-cutter i00 is at the leading end of the biade 15 in the rotational direction 125 and machines away a portion of the abradabfe material 32 during a tip rub event.
• the cutter-profile 102 is such that the cutter-angle J 04 makes contact with the abradabie material 32 at an angie to machine it, and arcuate recess 106 removes the machined abradabie material 32 away from the tip 61.
• F ⁇ G. 5 shows a schematic view of an alternative exemplary embodiment of the present invention of a blade 170 having features to reduce tip rub loads as described before.
• the exemplars' blade 170 shown in FIG 5 is a fan blade that may be used with gas turbine engine 10 (shown in FlG. 1 ).
• the fan blade 170 includes an airfoii 154, a blade tip cap 150 that cooperates vvith a radially innermost surface (not shown) of casing J 7 to form clearance 33 (shown in FlG. 1 ) therebetween.
• cap 150 is formed from titamum sheet metal.
• cap 150 is formed from any material that facilitates operation of blade 170 as described herein.
• Blade 170 also includes a dovetail root portion 152 that facilitates coupling to a rotor hub 21
• the airfoil 154 of blade 170 is formed from materials via processes that are both known in the art. Such materials include, but are not limited to, composites.
• Blade 170 also includes a trailing edge guard 156.
• guard 156 is formed from titanium sheet metal.
• guard 156 is formed from airs- material that facilitates operation of blade 170 in the engine H ) .
• Airfoil 154 has a first radial length 157.
• Blade 170 further includes a metal leading edge (MLE) 158.
• MLE 158 is formed from any metallic material that facilitates operation of fan rotor assembly 13 in the engine 10. including, but not being limited to, titanium alloys aid inconei alloys.
• MLF 158. as well as cap 150 and guard 156, are coupled to airfoil 154 via methods known in the art. wherein such methods include, but are not limited to. brazing, welding, and adhesive bonding.
• MLE 158 includes a solid nose region 160 and a plurality of sidewalks 162 (only one facing sidevvail .162 shown in FIG 5) MLE 158 extends along substantially ail of airfoil radial length 157.
• MLE 158 is configured with a second radial length 163 that is greater than first radial length 157 Alternatively, length 163 is any value that facilitates operation of blade 170 during tip rub events as described previously herein.
• the blade 1 70 and casing 37 cooperate to form clearance 33 therebetween.
• rotor blade 170 tip 61 may contact the abradable material 32 that surrounds the blade tips (See FIGS 1 and 4).
• unbalanced conditions within engine 10 may facilitate a decrease in a radial distance between lip cap 150 and casing 17 thereby increasing a probability of contact, or rub, between cap 150 and the abradable material 32 in the casing 1 7.
• Such rubbing will induce radial and tangential forces, wherein a least a portion of such loads will be transferred into casing 1 7 and a portion into airfoil 154.
• the alternative exemplary embodiment of blade 170 shown in FlG. 5 has features located in the blade tip portion 60 that reduce the tip rub loads as described previously herein.
• the blade 170 has a tip-cutter 100 (described previously herein) located at the tip portion 60 of the blade leading edge solid nose region 160.
• the tip-cutter 100 has a culler-profile 102 having a flat portion 108. cutter-angle 104 and an arcuate recess 106 as described previously herein.
• the tip-culler 100 is configured such thai, during up rub events, it makes contact with the abradable material 32 at an angle and machines away the abradable material 32 resulting in reduced rub loads.
• the cutter-profile 102 recess 106 is such that the abradable material 32 that is machined is removed away from the contact region.
• the cutter-angle 104 may have a value between about 1 degree and about 10 degrees, hi a preferred embodiment, the cutter-angle 104 has a value between about 2 degrees and about 5 degrees.
• the tip-grinder 120 is made from a ceramic, metallic or interm ⁇ tallic material having a composition comprising of embedded abrasive material, ⁇ n the case of metallic and intermetailic particles the hardness of the material would be in excess of Vickers 750 (g/mm ⁇ 2).
• Known abrasive materials may be used in the tip-grinder 120, Preferred known abrasive materials used for the tip-grinder 120 include Aluminum Oxide, Silicon Carbide, CBN or Diamond.
• the tip-grinderl 20 may be bonded to the MLE 158 or tip cap 150 using known methods such as brazing and welding In a preferred embodiment, the tip-grinder 120 is bonded to the MLE 158 by brazing.
• the tip-grinder 120 may be bonded or applied to the MLE 158 and/or tip cap 150 by thermal spray or using a known bonding adhesive.
• blade 170 shewn in FiO. 5 may further comprise a tip-rake 1 10 (See FIG. 4 for example) extending between the first and second sidewalls 44, 46. located on at least a part of ⁇ he tip portion 60 of the tip cap 150.
• the tip-rake I U has a rake-profile S 12 that facilitates reducing loading induced to the airfoil 42 during tip rubs, As described previously herein (see FlO.
• the rake-profile 1 12 has a rake angle 1 14 OW) such that during tip rub event, contact between the blade tip 61 and abradable material 32 occurs at the concave edge of the blade tip to reduce rub loads.
• the tip-rake 1 H may have a rake angle i 14 between about 2 degrees and about 15 degrees.
• the tip-rale 1 10 has a rake angle J J 4 between about 3 degrees and about 5 degrees
• FIG. 6 is a flow chart showing the steps of a method 300 of reducing tip rub loading.
• the method 300 comprises the step 305 of selecting a location of contact during a tip aib event between the tip of the blade and a static structure, such as lhe abradable material 32 This is illustrated in FIG. 4, for example, wherein the location of contact is chosen as the pressure side 44 leading edge tip.
• Step 31(s comprises selecting cutter-profile 102 (described previously herein) for the tip- cutter 100.
• Step 315 comprises the optional step of selecting a lip-grinder 120, Suitable materials capable of machining the abradable 32 can be chosen, as described previously.
• Step 320 comprises the optional step of selecting a tip rake-proftSe. also described previously herein.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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• 2010
  • 2010-06-02 WO PCT/US2010/036996 patent/WO2011002570A1/en active Application Filing
  • 2010-06-02 JP JP2012517542A patent/JP5628307B2/ja not_active Expired - Fee Related
  • 2010-06-02 EP EP10727571A patent/EP2449216A1/de not_active Withdrawn
  • 2010-06-02 CA CA2766534A patent/CA2766534C/en not_active Expired - Fee Related

Non-Patent Citations (2)

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