Abstract:
The invention relates to a blade of a compressor or of an axial-flow turbomachine. The blade comprises a joining airfoil, or main airfoil, extended by branches, or auxiliary branch airfoils. The branches are adjacent and extend the joining airfoil radially. The branches form a row over the circumference and comprise faces facing one another. The branches comprise joining edges connected to the joining airfoil and are coincident or joined so as to form a circumferential material continuation between the adjacent branches. The leading edges and the trailing edges of the branches are a continuation of the leading edges and the trailing edges of the joining airfoil. The branch airfoils offer more anchoring points for a blade. The overlap of the branch airfoils strengthens the edges of the joining airfoil, which can thus be formed thinner. The blade comprises a fixing platform connected to the branch airfoils.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit, under 35 U.S.C. §119, of EP 14177988.4, filed Jul. 22, 2014, the disclosure of which is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    The invention relates to a turbomachine blade. More precisely, the invention relates to a. The invention also relates to a blading with a row of branched blades. The invention also relates to a turbomachine comprising a blade having branches blade and/or a blading with a row of branched blades. 
       BACKGROUND 
       [0003]    An axial-flow turbomachine blade generally has a profiled airfoil extending in the flow of the turbomachine. To reduce the number of blades in a row whilst maintaining performance, it is known to provide a blade with branches. 
         [0004]    Document FR 2 914 943 A1 discloses a fan blade of an axial-flow turbomachine. The blade comprises a first portion extending from a fan means, and a plurality of other portions extending the first portion radially outwardly. All of these portions are connected by a platform disposed at the outer end of the first portion. However, this blade design has reduced rigidity. The presence of the platform in the middle of the fluid stream may disturb the flow. During operation, the branches are subjected to vibrations and forces that may damage the blade. The blade has a significant mass. The presence of the branches stresses the platform; the mechanical strength of the platform means it has to be made thicker, which disturbs the flow. 
       SUMMARY 
       [0005]    One object of the invention is to overcome at least one of the problems posed by the prior art. More precisely, an object of the invention is to increase the rigidity of a turbomachine blade with branches. A further object of the invention is to make rigid a turbomachine blading with branched blades. Another object of the invention is to protect the turbomachine in the event of ingestion. 
         [0006]    The invention relates to a blade of a turbomachine comprising: a joining airfoil intended to extend over its height H 1  through a flow of the turbomachine, at least two branch airfoils, which are connected to the joining airfoil, extending the joining airfoil over the height H 1  thereof, noteworthy in that the at least two branch airfoils comprise joining edges at least partially coincident so as to join the branch airfoils to one another along the joining airfoil. 
         [0007]    In accordance with various advantageous embodiments of the invention the joining edges of the branch airfoils are joined over the majority, for example, over all of their lengths L and/or of the length of the chord of the joining airfoil. 
         [0008]    In accordance with various advantageous embodiments of the invention the blade comprises a support connected to the branch airfoils on the side opposite the joining airfoil, and/or a support connected to the joining airfoil on the side opposite the branch airfoils, at least one support can be a fixing platform and comprising a fixing means. 
         [0009]    In accordance with various advantageous embodiments of the invention the airfoils comprise leading edges and trailing edges, the leading edge of the joining airfoil being extended radially by the leading edges of the branch airfoils, and/or the trailing edge of the joining airfoil being extended radially by the trailing edges of the branch airfoils, the leading edges and the trailing edges of the branch airfoils can be tangential to the leading edge and the trailing edge of the joining airfoil respectively. 
         [0010]    In accordance with various advantageous embodiments of the invention the branch airfoils form a thickened portion in the blade compared with the joining airfoil, each airfoil can have an intrados surface and an extrados surface, the joining edges being delimited by the intrados surface and by the extrados surface of the joining airfoil. 
         [0011]    In accordance with various advantageous embodiments of the invention each airfoil comprises a radial stack of aerodynamic profiles, the stacks of profiles of the branch airfoils diverging from the stack of profiles of the joining airfoil such that at least one profile of the branch airfoil is at a distance from at least one profile of the joining airfoil measured in the plane of the profile of the joining airfoil. 
         [0012]    In accordance with various advantageous embodiments of the invention the mean thickness of the aerodynamic profiles of the branch airfoils is less than the mean thickness of the profiles of the joining airfoil. 
         [0013]    In accordance with various advantageous embodiments of the invention the branch airfoils delimit, therebetween, a space passing through the blade along the chord of the joining airfoil, the space can be in the extension of the height H 1  of the joining airfoil. 
         [0014]    In accordance with various advantageous embodiments of the invention, each airfoil comprises an intrados surface and an extrados surface, the intrados surface and/or the extrados surface of the joining airfoil being tangential to the intrados surface of a branch airfoil and/or to the extrados surface of a branch airfoil. 
         [0015]    In accordance with various advantageous embodiments of the invention, the at least two branch airfoils have faces facing one another, the at least two branch airfoils can form a circumferential row. 
         [0016]    In accordance with various advantageous embodiments of the invention at least one or each branch airfoil is generally inclined relative to the joining airfoil, at least one or each branch airfoil can have an inversion of curvature radially in relation to the joining airfoil. 
         [0017]    In accordance with various advantageous embodiments of the invention, each branch airfoil or a plurality of the branch airfoils comprises/comprise aerodynamic profiles cambered in the same direction, the profiles having spacings that are generally constant along the joining airfoil so as to support a flow in the turbomachine. 
         [0018]    In accordance with various advantageous embodiments of the invention the branch airfoils have generally parallel chords at least at one given height so as to guide a flow in the turbomachine. 
         [0019]    In accordance with various advantageous embodiments of the invention the branch airfoils and the joining airfoil are integral and are made by powder-based, e.g., metal powder-based, additive manufacturing. 
         [0020]    In accordance with various advantageous embodiments of the invention the branch airfoils have the same heights, e.g., radial heights, and/or the same lengths, e.g., axial lengths. 
         [0021]    In accordance with various advantageous embodiments of the invention the blade comprises a fixing means, the branch airfoils extending over their height H 2  between the fixing means and the joining airfoil, or the airfoil extending over its height H 1  between the fixing means and the branch airfoils. 
         [0022]    In accordance with various advantageous embodiments of the invention at least one branch, or the majority of branches, or each branch forms an inversion of curvature in relation to the airfoil of the blade. 
         [0023]    In accordance with various advantageous embodiments of the invention at least one branch airfoil, or the majority of branch airfoils, or each branch airfoil has/have a radial height less than the joining airfoil. 
         [0024]    In accordance with various advantageous embodiments of the invention the blade is a stator vane or a rotor blade. 
         [0025]    In accordance with various advantageous embodiments of the invention at least one or each branch airfoil has a height H 2  greater than 5%, e.g., greater than 10%, e.g., greater than 20% of the height H 1  of the joining airfoil. 
         [0026]    In accordance with various advantageous embodiments of the invention the blade is a compressor blade, for example, a low-pressure compressor blade, or a turbine blade, or a fan blade. 
         [0027]    In accordance with various advantageous embodiments of the invention the length of the chord of the joining airfoil is greater than or equal to the chord of each branch airfoil. 
         [0028]    In accordance with various advantageous embodiments of the invention the branch airfoils, from the joining airfoil, converge towards one another along their height H 2  and their length L. 
         [0029]    In accordance with various advantageous embodiments of the invention the joining edges overlap axially so as to form an axial contact. 
         [0030]    In accordance with various advantageous embodiments of the invention the joining edges are anchored on one another or to one another. 
         [0031]    In accordance with various advantageous embodiments of the invention the faces of the branch airfoils facing one another match one another at the joining airfoil. 
         [0032]    In accordance with various advantageous embodiments of the invention the joining airfoil comprises an aerodynamic profile that brings together the branch airfoils. 
         [0033]    In accordance with various advantageous embodiments of the invention the joining airfoil is divided along its thickness into a plurality of branch airfoils. 
         [0034]    In accordance with various advantageous embodiments of the invention the branch airfoils delimit the joining airfoil in the height direction thereof. 
         [0035]    In accordance with various advantageous embodiments of the invention the mean space between two adjacent branch airfoils is greater than half the mean thickness, for example, greater than the mean thickness of the joining airfoil that is joined there. 
         [0036]    In accordance with various advantageous embodiments of the invention the mean space between two adjacent branch airfoils is less than the mean chord, for example, less than half the mean chord of the joining airfoil that is joined there. 
         [0037]    In accordance with various advantageous embodiments of the invention each branch airfoil, in the height direction thereof, comprises at least two portions that are generally inclined in relation to one another. 
         [0038]    The invention also relates to a blading comprising blades, noteworthy in that the blades are formed in accordance with the various embodiments of the invention as described herein. 
         [0039]    The invention also relates to an axial-flow turbomachine comprising at least one blade, noteworthy in that the at least one blade is formed in accordance with the invention. In various embodiments, the turbomachine comprises a compressor with rows of blades, at least one or each compressor blade being formed in accordance with the invention. 
         [0040]    In accordance with various advantageous embodiments of the invention the blades form bladings according to the various embodiments described herein. 
         [0041]    Each advantageous embodiment of the invention can apply to the other objects of the invention. Each object of the invention can be combined with the other objects of the invention. 
         [0042]    As described herein, in various embodiments, invention proposes a turbomachine blade, in particular a compressor turbomachine blade, comprising a plurality of auxiliary airfoils that are joined along a common joint, and a joining airfoil that extends the common joint along the height H 1  of the joining airfoil. 
         [0043]    The invention makes it possible to make the blade rigid. In fact, the branch airfoils form an angle at the end of the joining airfoil where the branch airfoils are joined. The edge of the joining airfoil is made rigid, the mechanical strength thereof no longer being dependent solely on the central part of the joining airfoil. As a result, the central part can be made thinner and further optimized. The aerodynamic gain and the strengthening make it possible to reduce the number of blades in a blade stage. 
         [0044]    The invention makes it possible to strengthen the blading by forming joints between the adjacent lateral branches. The shroud or the shroud segment forms a bridge connecting the ends of the branches within the same blade, or connecting the ends of the branches of one blade to another adjacent blade. The branches are thus protected against vibrations, which could damage the branches. 
         [0045]    The presence of branches between an airfoil and a shroud multiplies the anchoring points, the transmission zones and the distribution of forces. The joining of two adjacent blade branches also makes it possible to distribute forces in different blades. In addition, the formation of spacings in a row of connected branches makes it possible to optimize the flexibility, the rigidity and the transmission of forces in a blading. 
         [0046]    The invention makes it possible to increase the number of airfoils that could intercept a body in the event of ingestion. The body can be slowed down and in some instances can be trapped or further divided thanks to the added leading edges. The ingested bodies thus tend to be reduced upstream, which makes it possible to protect the elements downstream. The positioning of branches at the end of the airfoil makes it possible to act effectively against the fragments in the vicinity of the walls of the fluid streams, which constitute locations where the fragments are frequently found due to flow dynamics and/or inclinations of the fluid streams. 
         [0047]    The configuration in which the branches overlap axially makes it possible to form reinforcements making the airfoil rigid. The airfoil can thus be made thinner and lighter because it is less exposed to torsion. The profiles of the airfoil can be better adapted to the aerodynamic needs. This configuration strengthens the connections between the branches, which makes the branches more resistant to ingestions. 
     
    
     
       DRAWINGS 
         [0048]      FIG. 1  shows an axial-flow turbomachine according to various embodiments of the invention. 
           [0049]      FIG. 2  shows a diagram of a turbomachine compressor according to various embodiments of the invention. 
           [0050]      FIG. 3  illustrates a blading in accordance with various embodiments of the invention. 
           [0051]      FIG. 4  illustrates a blading in accordance with various other embodiments of the invention. 
           [0052]      FIG. 5  illustrates a blading in accordance with yet other embodiments of the invention. 
           [0053]      FIG. 6  illustrates a blading in accordance with still other embodiments of the invention. 
           [0054]      FIG. 7  illustrates a blading in accordance with a still yet other embodiments of the invention. 
           [0055]      FIG. 8  illustrates a blade in accordance with various other embodiments of the invention. 
           [0056]      FIG. 9  illustrates a blade in accordance with still yet other embodiments of the invention. 
           [0057]      FIG. 10  illustrates a blade in accordance with yet still other embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0058]    In the description below the terms internal or inner and external or outer relate to a positioning in relation to the axis of rotation of an axial-flow turbomachine. 
         [0059]      FIG. 1  shows an axial-flow turbomachine in a simplified manner. In this specific case the axial-flow turbomachine is a bypass turbojet. The turbojet  2  comprises a first compression level, referred to as a low-pressure compressor  4 , a second compression level, referred to as a high-pressure compressor  6 , a combustion chamber  8 , and one or more turbine levels  10 . During operation the mechanical power of the turbine  10  transmitted via the central shaft to the rotor  12  sets in movement the two compressors  4  and  6 . The different turbine stages can each be connected to compressor stages via concentric shafts. The shafts have a plurality of rows of rotor blades associated with rows of stator blades. The rotation of the rotor about the axis of rotation  14  thereof thus makes it possible to generate a flow of air and to progressively compress the flow of air as far as the inlet of the combustion chamber  8 . 
         [0060]    An inlet ventilator referred to commonly as a fan or blower  16  is coupled to the rotor  12  and generates a flow of air that is divided into a primary flow  18  passing through the different above-mentioned levels of the turbomachine  2  and a secondary flow  20  passing through an annular conduit (shown in part) along the length of the machine so as to then re-join the primary flow at the outlet of the turbine. The secondary flow can be accelerated so as to generate a reaction. The primary flow  18  and secondary flow  20  are annular flows and are channeled by the casing of the turbomachine. For this purpose, the casing has cylindrical walls or shrouds, which can be internal and external. 
         [0061]    The turbomachine can comprise a compressor or a compressor portion in which the flow circulates radially. The turbomachine  2  can also comprise a similar turbine. The blades, in particular the leading edges thereof and/or the trailing edges thereof, can extend radially or axially. 
         [0062]      FIG. 2  is a sectional view of an axial-flow turbomachine compressor  2  such as that in  FIG. 1 . The compressor can be a low-pressure compressor  4 . Here, part of the fan  16  and the separation beak  22  of the primary flow  18  and the secondary flow  20  can be seen. The rotor  12  comprises a number of rows of rotor blades  24 , in the present case three. 
         [0063]    The low-pressure compressor  4  can comprise a plurality of rectifiers, in the present case four, which each contain a row of stator blades  26 . The rectifiers are associated with the fan  16  or with a row of rotor blades in order to rectify the flow of air so as to convert the speed of the flow into pressure. 
         [0064]    The stator blades  26  extend essentially over the height thereof through the flow  18 , e.g., radially, from an outer casing  28  and can be fixed there with the aid of a pin, e.g., formed on a fixing platform. 
         [0065]    The blades ( 24 ,  26 ) can be fixed individually to the stator or to the rotor  12 , or can be grouped into bladings comprising a plurality of blades forming a row over the circumference. The blades ( 24 ,  26 ) can be grouped into bladed casings, with a plurality of blades and a shroud, or with two concentric shrouds ( 30 ,  32 ) between which the blades ( 24 ,  26 ) extend radially. 
         [0066]    A blading can be monoblock, e.g., it can be formed in one piece, e.g., via an additive manufacturing process. It can also be formed by soldering branches and airfoils to one another. 
         [0067]    The rotor blades  24  and/or the stator blades  26  of the compressor can be branched. The branch designs can vary from one blade row to the other and can be branched at the blade foot and/or blade head. The joints  27  between the branches and the blade airfoils are visible. 
         [0068]      FIG. 3  shows a turbomachine blading  34  in accordance with various embodiments of the invention. The blading  34  shown is a stator blading, but could also be a rotor blading. 
         [0069]    A blading  34  can be understood to be a surface, e.g., a rigid surface, making it possible to guide a flow of fluid. It can be understood to be a set of blades  26 . The blading can be and/or can comprise a row of blades, with a plurality of blades  26 , forming a portion of an annular row. The blades  26  are disposed on a wall, such as a shroud or a shroud portion, e.g., an inner shroud portion  32 . The wall, or shroud portion can have the shape of a circle or arc of a circle. 
         [0070]    Each blade  26  can protrude, e.g., extend radially, from the shroud  32 . Each blade  26  comprises an airfoil  36  and branches  38  or branching. The airfoil  36  can be a joining airfoil  36  combining the branches  38 , the branches can be branch airfoils  38 . The branches  38  of the same blade are spaced from one another in the circumferential direction. 
         [0071]    Each airfoil  36  and/or each branch  38  can have a general leaf shape, which can generally extend in a primary plane, the leaf can be substantially curved and/or having a variable thickness. An airfoil has a leading edge  40  and a trailing edge  42 , which delimit an intrados surface and an extrados surface. 
         [0072]    The branches  38  can be lateral branches  38  in the sense that they are laterally spaced from the airfoil  36  in the direction of thickness thereof and/or perpendicularly to the court of the airfoil  36 . Each branch  38  has two opposite ends in the direction of height, e.g., the radial height, of the airfoil. One of the ends is joined to the airfoil  36  and the other is joined to the shroud  32 , which forms a support. The shroud  32  and the blades can be formed integrally, or the shroud can comprise openings  44  in which the ends of the branches are fixed and/or sealed. 
         [0073]    The shroud  32  can be a portion of an outer casing, or a rotor wall, such as a rotor drum wall. The shroud can form a circle or an angular portion of a circle, such as an arched material strip. 
         [0074]    The height of a branch  38 , of an airfoil  36 , or of the blade  26  can be perpendicular to the leading edge and/or the trailing edge of the airfoil, and/or can be oriented perpendicularly to the fluid. The airfoil and the branches are intended to extend in the flow of the turbomachine. 
         [0075]    The branches  38  of adjacent blades  26  are distanced from one another and allow a passage between the blades along the extrados surface of the shroud  32 . In combination with the shroud, the branches of at least one or each blade form a conduit  48 , which passes through the blade  26 . This conduit  48  is configured to support a flow of the turbomachine. The upper ends of the airfoils are free and form edges. 
         [0076]      FIG. 4  shows a blading  134  in accordance with various other embodiments of the invention. This  FIG. 4  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 100. The figure shows a row of blades  126 , in various instances it can include a shroud. Each blade  126  is shown in the form of a curve, which can correspond to a leading edge and/or to a trailing edge and/or to a stacking curve of aerodynamic profiles of an airfoil or branch. 
         [0077]    The row comprises a plurality of blades  126 , each with branches  138  at the same end or on a same side of the airfoil  136 . The branches  138  extend over the circumference in the direction of the adjacent blade  126 , and in particular of the branches  138  of the adjacent blades. The adjacent branches  138  of two adjacent blades  126  are joined, for example at a radial end of the blade, such as the end opposite the end receiving the airfoil. Thus, the blades  126  form a chain of blades, with continuation of circumferential material, which are connected to one another with the aid of their branches  138 . 
         [0078]    The term joined can mean that the branches  138  or the branch airfoils  138  comprise joining edges or coincident edges. At the joining point of the branches, the total thickness can be less than the addition of the thicknesses of each branch. 
         [0079]    At least two adjacent branches or each pair of adjacent branches  138  of adjacent blades  126  can form therebetween a channel  150 . A channel  150  can be understood to mean an elongate depression, such as a passage delimited laterally between two opposite branch walls. 
         [0080]      FIG. 5  shows a blading  234  in accordance with yet other embodiments of the invention. This  FIG. 5  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 200. 
         [0081]    The blading  234  comprises a row of blades  226  with a plurality of blades forming an angular portion of an annular row. The row can form a circle. The blades  226  are disposed on a wall, such as a shroud ( 230 ,  232 ) or a shroud portion. The wall or shroud portion can have the shape of a circle or arc of a circle. 
         [0082]    The blading can be a bladed casing. It can comprise at least three blades  226  each with an airfoil and branches extending the airfoil in the direction of the radial height of the airfoil. The airfoils, including the branches thereof, can be distanced from one another. 
         [0083]    The blading  234  comprises two shroud segments, such as an inner shroud segment  232  and an outer shroud segment  230 , which can be understood to be angular sectors of tubes. The segments are concentric and define a fluid stream of which the middle in the radial height direction is located in line with the airfoil, e.g., at mid-height. 
         [0084]    At least one or each blade  226  can comprise two sets of branches  238 , which are each joined to one end of the airfoil  236  and to a shroud segment ( 230 ,  232 ). The shroud segments are thus connected to one another via, in this order, first sets of branches  238 , airfoils  236 , and second sets of branches  238 . Each branch is joined to the blade and/or to a shroud over the majority, e.g., over the entire length thereof. 
         [0085]    The sets of branches  238  of at least one blade or each blade can have different numbers of branches. The sets having most branches  238  can be arranged on the same side of the airfoil  236 . The arrangements of branches can vary from one set to another adjacent set. 
         [0086]    For example, one set can comprise at least three branches, of which two branches  238  are side branches over the circumference, between which at least one central branch  238  is disposed. These branches  238  can all be joined by each having a joining edge; the edges being coincident. At least one or each blade  226  can have branches  238  that are joined to the airfoil  236  at different heights. A branch  238  can extend from another branch  238  remaining at a distance from another branch and/or from the airfoil  236 . A branch  238  of this type can form a strut that makes the blading  234  rigid. A branch  238  can extend laterally from one side of the airfoil  236 , then from the other, or can extend only from one side of the airfoil  236 . 
         [0087]      FIG. 6  shows a blading  334  in accordance with still other embodiments of the invention. This  FIG. 6  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 300. The blading shown is a stator blading, but alternatively could be associated with the rotor. 
         [0088]    The blading  334  has a plurality of sets of blades. Each set can form an angular portion of an annular row of blades. Each set of blades has a plurality of blades  326 , each with an airfoil  336  and branches  338  extending the airfoil  336  in the direction of height thereof, e.g., in the direction of radial height thereof. Each blade  326  can have two sets of branches. Adjacent branches  338  of a set of blades  326  can be joined on a radial side, the branches  338  remaining at a distance on the other side. The sets of blades can be distanced from one another. In particular, the branches of a set of blades can be distanced, over the circumference, from each branch  338  of an adjacent set of blades. 
         [0089]      FIG. 7  shows a blading  434  in accordance with still yet other embodiments of the invention. This  FIG. 7  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 400. Specific numbers are used for the elements specific to this embodiment. 
         [0090]    The blading  434  comprises a row of blades  426  forming at least one portion of an annular turbomachine row. The blades  426  are disposed on a wall, such as a shroud or a shroud portion ( 430 ,  432 ). The wall or shroud portion can have the shape of a circle or an arc of a circle. 
         [0091]    The row can have a mixed arrangement of blades  426 . Some blades  426  can be free from branches at least at one end or at each end. The number of branches  438  on the same radial side of the blading can vary between the blades  426 . Some or all the adjacent branches  438  of different blades  426  can be joined. On one radial side of the blading, the branches can form a row and/or can be joined to one another so as to form a chain of branches  438 , which can also be joined to a shroud  430  in addition to associated airfoils  436 . This double joining of the branches makes the shroud rigid and the arts makes the blading rigid with respect to torsional forces. 
         [0092]      FIG. 8  shows a blade  526  in accordance with various other embodiments of the invention. This  FIG. 8  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 500. Specific numbers are used for elements specific to this embodiment. The blade  526  can be a stator blade  526  as shown in  FIG. 2 . 
         [0093]    The blade  526  comprises an airfoil  536  and at least two branches  538 , e.g., three or more branches  538 . The airfoil  536  can be a joining airfoil  536  or a main airfoil  536  in the sense that the height and/or thickness thereof is greater than that of each branch  538 . The joining airfoil  536  forms a joining portion  552 , and the branches  538  form a branch portion  554 , the portions being superimposed in the height direction. 
         [0094]    The branches  538  can be branch airfoils  538  that are joined by the joining airfoil  536 . For this purpose they can comprise joining edges that are at least partially, e.g., completely coincident along the chord of the joining airfoil. The joining edges  556  can form ends or delimitations of the branch airfoils  538 . The joining airfoil  536  and the branch airfoils  538  are intended each to be disposed in the flow of the turbomachine. 
         [0095]    The joining airfoil  536  is disposed in the extension of the branch airfoils  538  at the joining point therebetween. The joining airfoil  536  can form the joining point between the branch airfoils  538 . These can form divisions of the joining airfoil. They can form legs  538  separating from the joining airfoil at a branching point. The joining airfoil  536  can divide or separate into branch airfoils. The branches can be anchored to one another and/or on one another. 
         [0096]    The joining airfoil  536  and/or each branch airfoil  538  can comprise a leading edge  540  and a trailing edge  542 . The joining airfoil and/or each branch airfoil can comprise an intrados surface and an extrados surface extending from the leading edge  540  to the corresponding trailing edge  542 . The intrados surface and the extrados surface of the joining airfoil are tangential, e.g., along the entire length of the chord of the airfoil, to the adjacent surfaces of the branch airfoils  538 . 
         [0097]    The joining airfoil  536  and/or each branch airfoil  538  can comprise aerodynamic profiles  558 , which are in some instances cambered and which are stacked in the height direction, e.g., in the radial height direction. The centers of gravity of the aerodynamic profiles  558  of the joining airfoil  536  and/or of each branch airfoil  538  can describe a stacking curve  560 . The stacking curves  560  of the branch airfoils  538  can be in the radial and/or axial and/or circumferential extension of the stacking curve  560  of the joining airfoil  536 , in some instances becoming progressively offset in relation thereto. The branch airfoils can define a channel  562  therebetween, in some instances at a distance from the joining airfoil  536 . The height H 1  of the joining airfoil  536  can be greater than or equal to the height H 2  of each branch airfoil  538 . 
         [0098]    The leading edges  540  and/or the trailing edges  542  and/or the stacking curves  560  of each branch airfoil  538  can have a variation, e.g., an increase, and/or an inversion of curvature in relation to, respectively, the leading edge  540  and/or the trailing edge  542  and/or the stacking curve  560  of the joining airfoil  536 . 
         [0099]    The maximum thickness of the aerodynamic profiles  558  of the joining airfoil  536  can be greater than the maximum thickness of the aerodynamic profiles  558  of each branch airfoil  538 . The surface of each aerodynamic profile  558  of the joining airfoil can be greater than or equal to the surface of each aerodynamic profile of at least one or each branch. The addition of the surfaces of the aerodynamic profiles of the branches at a given height can be greater than or equal to the surface of each aerodynamic profile of the airfoil. 
         [0100]    The blade  526  has at least two branch airfoils  538 , e.g., three or four, or even more at one end. The blade  526  can comprise a support  564  joined to the branch airfoils. The support  564  can be a fixing platform  564 , for example equipped with a fixing pin  566 . The branch airfoils  538 , the joining airfoil  536 , and in some instances the support  562  can be integral. They can be provided by additive manufacturing with a titanium powder. 
         [0101]    At least one or each branch airfoil  538  can comprise parts, over the height of the blade, that are inclined in relation to one another. These parts can be curves and can have variations or inversions of curvature. Along the height, the mean axis of the stacking curve  560  of at least one or each branch airfoil  538  is inclined in relation to that of the joining airfoil  536 . These geometries can be observed at the leading edge  540  and/or the trailing edge  542  and/or the stacking curve  560  of the profiles  558 . 
         [0102]    The distance E between the branch airfoils  538 , measured opposite the joining airfoil  536  at the leading edges  540  thereof or at the trailing edges  542  thereof or at the maximum passage width, is greater than the majority of the mean or maximum thickness of the joining airfoil  536 . The distance E can be less than the length L of the branch airfoils  538  and/or less than the height H 2  of the branch airfoils. For at least one or each branch airfoil  538 , the length L can be greater than or equal to the height H 2 . 
         [0103]      FIG. 9  shows a blade  626  in accordance with still yet other embodiments of the invention. This  FIG. 9  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 600. Specific numbers are used for the elements specific to this embodiment. 
         [0104]    The blade  626  comprises two branched portions  654  joined by a joining portion  652 . The joining airfoil  636  of the blade  626  comprise two ends  668  that are opposite over the height of the joining airfoil, for example radial ends, such as a head and a foot. The joining airfoil  636  can comprise branch airfoils  638  at each of the radial ends thereof, the branch airfoils forming a first set and a second set of branch airfoils  638 , each set being joined to one of the ends  668  of the joining airfoil  636 . The height H 2  of the branch airfoils can vary from one set to another and can remain less than the height H 1  of the joining airfoil  636 . 
         [0105]    The ends of branch airfoils can be free edges  670 . They can form edges in the form of cambered aerodynamic blade profiles. The ends can have fixing means, such as fixing pins. The ends at the same end of a blade can each comprise a fixing orifice  672 , the orifices  672  can be aligned along the row formed by the associated branch airfoils. 
         [0106]      FIG. 10  shows a blade  726  in accordance with yet still other embodiments of the invention. This  FIG. 10  adopts the numbering of the previous figures for identical or similar elements, however the numbering is incremented by 700. Specific numbers are used for the elements specific to this embodiment. 
         [0107]    The blade  726  comprises a joining airfoil  736  with two ends  768  that are opposite in the height direction H 1 , each end  768  comprising branches  738  extending the airfoil in the height direction. Branches form a first set of branches at one end  768  of the airfoil  736 , and a second set of branches  738  at the other end  768 . The opposite ends  768  comprise a different number of branches  738 . 
         [0108]    The sets of branches can be superimposed in the height direction of the blade  726  whilst being separated by the airfoil  736 . One of the sets can cover the other set, the covering can be over the mean chord of the airfoil and/or over the thickness of the airfoil. 
         [0109]    One set of branches can be connected to a support  764 , such as a fixing platform  764 . The set of branches on the side opposite the support  764  can have free edges  770 , and in some instances a fixing means  774 , such as bosses  774  or bumps  774 . These means can be used to seal the branches to a wall, to a support, or to a shroud. 
         [0110]    The various embodiments of blades illustrated and described with regard to  FIGS. 3 and 7  can be formed in accordance with the various embodiments illustrated and described with regard to  FIGS. 8 ,  9  and/or  10 . A blading can comprise branches at each end over the height of the airfoils. The number of branches can be different at each of these ends. The various embodiments of the blades illustrated and described with regard to  FIGS. 9 and 10  can adopt the configurations of the blade illustrated and described with regard to  FIG. 8 , in particular with regard to the arrangement of the leading edges, the trailing edges, the joining edges, the stacking curves, and the arrangement of the branch airfoils in relation to the joining airfoil.