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
  • F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
  • F01D5/186—Film cooling
• • 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
  • F01D5/141—Shape, i.e. outer, aerodynamic form
• • 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
  • F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
  • F01D5/187—Convection cooling
• • 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
  • F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
• • 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

Definitions

• Jet turbine blade with offset to the underside of the head sections and cooling channels
• the field of the present invention relates to hollow blades, in particular blades for gas turbines, and more particularly turbomachine blades, and more particularly blades for a high-pressure turbine.
• a blade comprises in particular a blade extending in a longitudinal direction, a foot and a head opposite to the foot.
• the blade is fixed on the disc of a turbine rotor by means of its foot.
• the head of the blade is located opposite the inner face of the fixed annular casing surrounding the turbine.
• the longitudinal direction of the blade corresponds to the radial direction of the rotor or the turbomachine, and this with respect to the axis of rotation of the rotor.
• the blade can be decomposed into blade sections which are stacked in a stacking direction which is radial with respect to the axis of rotation of the rotor disk.
• the blade sections thus form an aerodynamic surface which is directly subjected to the gases passing through the turbine.
• This aerodynamic surface extends, from upstream to downstream in the direction of flow of the fluid, between a leading edge and a trailing edge, these edges being interconnected by an intrados face called the intrados and a face extrados called the extrados.
• the turbine provided with such blades is traversed by a gas flow.
• the aerodynamic surface of its blades must be used to transform the maximum kinetic energy from the gas flow into mechanical energy transmitted to the rotor shaft of the turbine rotor.
• the blade of the blade generates kinetic energy losses and should be minimized.
• a significant part of these losses is attributable to the presence of a functional radial clearance between the head of each blade and the inner surface of the casing surrounding the turbine.
• this radial clearance generates a gas leakage flow flowing from the lower surface (higher pressure zone) to the upper surface (lower pressure zone) of the blade.
• This leakage flow represents a non-working gas flow and does not participate not to relax in the turbine.
• he is at the origin of the development of a whirlwind at the head of the dawn (called tourbillon game) which generates significant kinetic energy losses.
• blade with "advanced blade tip” or "shift cuts in mind.”
• the turbine blades and in particular the high pressure turbine blades, are subjected to significant levels of external gas temperature from the combustion chamber. These levels exceed the allowable temperatures of the material of the blade, which leads to having to cool them. With recent engine design temperature levels continuing to rise to improve overall performance, it is becoming necessary to implement innovative high pressure turbine blade cooling systems to ensure an acceptable service life of the engine. these parts.
• the present invention therefore aims to provide a blade structure that allows to maintain a high efficiency of the cooling system at the top of the blade in the case of an advanced blade tip of the type "shift cups head" .
• the present invention relates to a hollow blade comprising a blade extending in a longitudinal direction, a foot and a head, an internal cooling passage in the blade, a cavity (or bath) located in the head, open in direction of the free end of the blade and defined by a bottom wall and a rim, said rim extending between the leading edge and the trailing edge and comprising an extrados rim along the upper surface and a flange of intrados along the lower surface, and cooling channels connecting said internal cooling passage and the intrados, said cooling channels being inclined with respect to the intrados, the stacking of the blade sections the dawn at the edge of the head of the blade having an offset in the direction of the intrados, this shift being more and more important approaching the free end of the head of the blade.
• This hollow blade is characterized in that the intrados wall of the blade has a protruding portion of which more than half the length extends along a longitudinal portion of the internal cooling passage, and whose outer face is inclined relative to the remainder of the underside of the blade and has at its end facing the cavity an end face, the bottom wall being connected to the intrados wall at the location of said end of said protruding portion and said cooling channels being disposed in said protruding portion so that they open on the end face of said projecting portion, whereby the distance d between the axis of the cooling channels and the outer limit of the end free of the intrados flange is greater than or equal to a minimum value dl non-zero.
• This value d1 thus corresponds to a predetermined threshold value according to the type of blade and the operating conditions of the drilling.
• This solution also has the additional advantage of allowing, in addition, an improvement in the cooling of the portion of the intrados wall carrying the heat pump cooling channels and a better film cooling of the intrados flange of the cavity. (or bathtub).
• the present invention also relates to a turbomachine rotor, a turbomachine turbine and a turbomachine comprising at least one blade as defined in the present text.
• FIG. 1 shows a perspective view of a hollow rotor blade for a conventional gas turbine
• FIG. 2 shows in perspective, in an enlarged manner, the free end of the blade of FIG. 1,
• FIG. 3 is a view similar to that of FIG. 2, after the trailing edge of the blade has been removed by a longitudinal section,
• FIG. 4 is a partial view in longitudinal section along the direction IV-IV of FIG. 3;
• FIGS. 5 to 7 represent views similar to that of FIG. 4, for blades incorporating the technique of "offset of cuts at the head",
• FIGS. 8 and 9 represent the solution according to the present invention.
• Figures 10 and 11 are views similar to that of Figure 8 for a first embodiment and a second embodiment.
• upstream and downstream are defined with respect to the normal flow direction of the gas (from upstream to downstream) through the turbomachine.
• the axis of the turbomachine is called the axis XX 'of radial symmetry of the turbomachine.
• the axial direction corresponds to the direction of the axis of the turbomachine, and a radial direction is a direction perpendicular to this axis and passing by him.
• an axial plane is a plane containing the axis of the turbomachine and a radial plane is a plane perpendicular to this axis and passing through it.
• the transverse (or circumferential) direction is a direction perpendicular to the axis of the turbomachine and not passing through it.
• the axial, radial, and transverse (and axially, radially and transversely) adjectives are used with reference to the aforementioned axial, radial and transverse directions.
• the internal and external adjectives are used with reference to a radial direction so that the part or the internal (ie radially internal) face of an element is closer to the axis of the turbomachine than the part or the outer (ie radially external) face of the same element.
• FIG. 1 is visible, in perspective, an example of a conventional hollow rotor blade 10 for a gas turbine. Cooling air (not shown) flows inside the blade from the bottom of blade root 12 into blade 13, along the longitudinal direction RR 'of blade 13 (vertical direction) in the figure and radial direction relative to the axis XX 'of rotation of the rotor), towards the head 14 of the blade (at the top in FIG. 1), then this cooling air escapes through an exit to join the main gas flow.
• Cooling air (not shown) flows inside the blade from the bottom of blade root 12 into blade 13, along the longitudinal direction RR 'of blade 13 (vertical direction) in the figure and radial direction relative to the axis XX 'of rotation of the rotor), towards the head 14 of the blade (at the top in FIG. 1), then this cooling air escapes through an exit to join the main gas flow.
• this cooling air circulates in an internal cooling passage located inside the blade and which ends at the head 14 of the blade at the level of through holes 15.
• the body of the blade is profiled so that it defines a lower surface wall 16 (on the left in all the figures) and an extrados wall 18 (on the right in all the figures).
• the intrados wall 16 has a generally concave shape and is the first face of the flow of hot gases, that is to say the gas pressure side, by its outer face, turned upstream, called the lower face. or more simply intrados 16a.
• the extrados wall 18 is convex and is subsequently present in the flow of hot gases, that is to say on the suction side of the gas, along its outer face, turned downstream, called the extrados face or more simply extrados 18a.
• intrados and extrados walls 18 are joined at the location of the leading edge 20 and at the trailing edge location. 22 which extend radially between the head 14 of the blade and the top of the foot 12 of the blade.
• the internal cooling passage 24 is delimited by the inner face 26a of a bottom wall 26 which extends over the entire head 14 of the blade, between the intrados wall 16 and the extrados wall 18, therefore from the leading edge 20 to the trailing edge 22.
• the intrados and extrados walls 16, 18 form the rim 28 of an open cavity 30 in the opposite direction to the internal cooling passage 24, radially outwardly (upwards in all the figures). More specifically, the flange 28 is constituted by the intrados flange 281 on the side of the intrados wall 16 and the extrados flange 282 on the side of the extrados wall 18.
• this open cavity 30 is therefore delimited laterally by the internal face of this flange 28 and in the lower part by the outer face 26b of the bottom wall 26.
• the flange 28 thus forms a thin wall along the profile of the blade which protects the free end of the head 14 of the blade 10 from contact with the corresponding inner annular surface of the turbine casing 50 (see FIG. 4). .
• inclined cooling channels 32 pass through the intrados wall 16 to connect the passage internal cooling 24 to the outer face of the intrados wall 16, namely the intrados 16a.
• These cooling channels 32 are inclined so that they open towards the top 28a of the rim so as to cool it, by means of an air jet which is directed towards the top 28a of the rim 28 along the intrados wall 16.
• the cooling efficiency resulting from these cooling channels 32 is mainly related to two geometrical parameters of these cooling channels 32 (see FIG. 4):
• the industrial feasibility of producing the cooling channels 32 (generally made in EDM drilling for "Electron Discharge Machining” or EDM) requires having a sufficient angle ⁇ between the axis of the cooling channels 32 and the outer face 281a of the underside 281 to provide a clearance sufficient to allow the passage of the EDM nozzle.
• the blade 10 ' which includes a "offset of the head cuts" bears the same reference signs as those of the blade of FIGS. 1 to 4, embellished with a premium ("'") for modified parts.
• the differences relate solely to the shape of the flange 28 'which is no longer parallel to the longitudinal direction R-R' or radial direction of the blade 10 '.
• Blade sections S are considered to correspond to the contour of the section of the blade in a plane of section orthogonal to the longitudinal direction RR 'or radial direction of the blade. For dawn 10, all blade sections S are stacked in one direction stacking parallel to the longitudinal direction RR 'or radial direction of the blade, being superimposed between them (see Figure 4).
• the blade sections S of the blade portion comprising the internal cooling passage 24 and the bottom wall 26 are also stacked in the radial direction of the blade; however, the blade sections S1, S2, S3 and S4 of the flange 28 '(head sections) are stacked with an offset of their stack towards the lower surface 16a, which is progressive and increases as it progresses. that the section is near the top 28a '(in the order SI, S2, S3 and S4 in Figure 5).
• end A of the intrados flange 281' is referred to.
• the rim 28 'illustrated further comprises an enlargement 283' of the intrados flange 281 'at the location of the outer limit A of the free end of said intrados flange 28, namely at the location of the intrados border of the summit 28a '.
• This enlargement 283 ' is present on a number of stacked sections (S3 and S4) in FIG. 5 and forms, in section, an end-point shape A and which is traversed by the axis of the cooling channel 32.
• This The tip shape that can appear when machining blade 10 should be considered non-mandatory and optional.
• a first solution visible in FIG. 6, with the cooling channels 32 'which can be pierced easily, consists in reducing the unclogging height R2 to the value R2' without modifying the total radial extent D (the height RI of the In this case, by decreasing the radius R2 and lowering the position of the outlet of the cooling ducts, satisfactory cooling of the head of the vane formed is no longer permitted. of the rim 28 ', a second solution visible in FIG.
• the present invention provides the solution shown in Figures 8 to 11 and described below.
• the blade 110 comprises a flange 28 'equipped with a "headset offset" as previously described in connection with FIG. 5.
• the intrados wall 16 is modified in its intermediate portion, which is adjacent to the intrados flange 281 ', in that this intermediate portion forms a protrusion in the direction of the intrados 16a.
• the intermediate portion is a protruding portion 161 in that in this projecting portion, the intrados 16a is not directed in the longitudinal direction RR 'or radial direction, but is inclined further apart of the extrados 18a as one approaches the flange 28 'in the longitudinal direction R-R'.
• this protruding portion 161 extends along a longitudinal portion of the internal cooling passage 24 (in this case the most radially outer portion in the geometry of the turbomachine).
• This protruding portion 161 extends over the entire height of the cooling channels 132, between the radii R2 and R1 (with R2> R1) and is materialized on the lower surface 16a by an outside face or intrados face 161a, a terminal face. 161b turned towards the flange 28 ', and an inner face 161c facing the internal cooling passage 24.
• the intrados face 161a of the protruding portion 161 is inclined away from the longitudinal direction RR 'as one approaches the end face 161b.
• the angle of inclination ⁇ formed between the intrados face 161a of the projecting portion 161 and the longitudinal direction RR 'or radial direction is between 10 ° and 60 °, preferably between 20 ° and 50 °, and advantageously between 25 ° and 35 °, namely close to 30 °.
• the inclination angle ⁇ of the cooling channels 132 with respect to the longitudinal direction RR 'or radial direction is between 10 ° and 60 °, preferably between 20 ° and 50 °, and advantageously between 25 ° and 35 °. °, namely close to 30 °.
• said minimum value d1 is greater than or equal to 1 mm or even 2 mm and depends on the equipment used to drill the cooling channels 132.
• said cooling channels 132 are disposed in said projecting portion 161 so that they open on the end face 161b of said projecting portion 161.
• This geometry generates a flow F2 in a recirculation zone (wedge zone) which allows an efficient mixing between the flow of cooling gas Fl and the hot external gases regardless of the position of the outlet opening of the cooling channels 132 on the end face 161b of said projecting portion 161.
• a projecting portion 161 makes it possible to further improve the cooling efficiency generated by the air coming from the cooling channels 132.
• the distance ⁇ (see FIG. 9) between the end B of the end face 161b of the protruding portion 161 and the remainder of the intrados wall 16 is at a minimum equal to the difference between the gap E, measured between the end A of the intrados flange 28 and the remainder of the intrados wall 16, and said distance d between the axis of the cooling ducts 132 and the end A of intrados flange 28: this distance ⁇ corresponds to the axial extent of the end face 161b of said protruding portion 161.
• the thickness e of the intrados wall 16 of the blade of the blade 110 is substantially constant between the protruding portion 161 and the remainder of the intrados wall 16, and is also substantially equal to the wall thickness of the area 161d of the protruding portion 161 (see Fig. 9) connected to the bottom wall at and from the front of the base of the intrados flange 28.
• wall thicknesses are considered taking the direction orthogonal to the outer face of the area to be considered.
• This characteristic is illustrated in FIG. 9, where this thickness e is found below the projecting portion 161, at the location of the projecting portion 161 along the cooling channels 132 and in the zone 161d situated between the end face 161b and the internal cooling passage and connecting the protruding portion 161 to the bottom wall 26.
• the rear face of the wall is hollowed out. extrados at the location of the projecting portion 161.
• the area to be removed behind the projecting portion 161 relative to the conventional profile of the intrados wall 16, visible by the lines PI and P2 in Figure 8 corresponds to the area C of FIG. 9.
• this design according to the invention with the protruding portion 161 which does not generate extra thickness can be obtained with a minimum of modification of pre-existing tools: in the foundry, the already existing core box is hollowed out with an equivalent volume of the extruded surface C (over the entire width of the intrados) in order to produce cores having the internal profile cavity adequate to obtain the projecting portion 161, and this volume is hollowed on the wax mold forming the outer envelope of the blade.
• the outer face 161a and the inner face 161c of the projecting portion 161 are parallel to each other.
• the end face 161b of the projecting portion 161 is flat.
• the end face 161b of the projecting portion 161 is horizontal: it is directed orthogonal to the longitudinal direction RR 'of the blade at the location where the cooling channels 132 open into said face terminal 161b.
• the entire end face 161b of the projecting portion 161 is directed orthogonal to the longitudinal direction R-R 'of the blade.
• a chamfer is used at the end face 161b, so that the end face 161b of the projecting portion 161 is inclined at an angle ⁇ which is not zero with the longitudinal direction RR dawn at the location where the cooling channels 132 open into said end face 161b.
• it is an acute angle ⁇ 2 which is formed between the end face 161b of the protruding portion 161 and the horizontal direction parallel to the axis XX 'of rotation of the rotor and orthogonal to the longitudinal direction RR' of the 'dawn.
• This angle ⁇ 2 is preferably between 10 ° and 60 °, preferably between 20 ° and 50 °, and preferably between 25 ° and 35 °, namely close to 30 °.
• the axis of the cooling channels 132 is orthogonal to the end face 161b of the protruding portion 161, at the location where the cooling channels 132 open into said end face 161b.
• the advantage of this variant is that the shape of the outlet opening of the cooling channels 132 on the end face 161b is round against a more oval shape when the end face 161b is horizontal, which makes it possible to better control the outlet section of the cooling channels 132 and thus the flow of cooling air.
• the bottom wall 26 is directed orthogonal to the longitudinal direction R-R 'of the blade, which corresponds to a conventional configuration.
• the end face 161b of the protruding portion 161 is disposed at the height of the unclogging radius R2 which is smaller than the radius R3 corresponding to the outer face 26b of the bottom wall 26 (see FIG. Figures 8 and 9) which is turned towards the cavity 30.
• R2 ⁇ R3 makes it possible to guarantee effective cooling of the bathtub bottom zone (if R2> R3 were used, the bottom of the bathtub would not be impacted by the cooling from the cooling channel 32.)
• the end face 161b of the protruding portion 161 is disposed at the height of the unclogging radius R2 which is greater than the radius R4 corresponding to the inner face 26a of the bottom wall 26 (see FIGS. 8 and 9) which is turned towards the internal cooling passage 24.
• R2> R4 makes it possible to ensure that the blade 110 will be cooled well above the zone not thermally covered by the cooling generated by the cavity 30.
• R2 ⁇ R3 and R2> R4 represents the best thermal compromise that can be found.
• an inclined bath floor is used in that said bottom wall 126 is inclined at an angle ⁇ different from the right angle and not zero with the longitudinal direction of the bath. 'R-R' dawn.
• the upper face of said bottom wall 126 forms, at the location adjacent the intrados flange 281 ', an acute angle ⁇ , preferably between 45 ° and 89 °, preferably between 50 ° and 65 ° and advantageously between 55 ° and 65 °, namely close to 60 °, which corresponds to an acute angle 52 between the upper face of said bottom wall 126 and the horizontal direction parallel to the axis XX 'of rotation of the rotor and orthogonal to the longitudinal direction RR 'of the dawn.
• ⁇ preferably between 45 ° and 89 °, preferably between 50 ° and 65 ° and advantageously between 55 ° and 65 °, namely close to 60 °

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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• 2011
  • 2011-11-17 FR FR1160465A patent/FR2982903B1/fr active Active
• 2012
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  • 2012-11-13 JP JP2014541733A patent/JP6073351B2/ja active Active
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  • 2012-11-13 RU RU2014124709A patent/RU2617633C2/ru active
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