METHOD FOR CORRECTING THE RADIAL MOMENT WEIGHT OF A VANE FOR AN AIRCRAFT TURBINE ENGINE

A method for correcting the radial moment weight of a vane includes the step of providing a vane extending along an axis of elongation (Z) between a free end and an opposite root, the vane having a blade made of composite material and having a leading edge. The method further includes the steps of measuring the radial moment weight of the vane and comparing the measured radial moment weight to a reference value and adjusting the radial moment weight of the vane according to the result of the comparison. The vane has at least one adjustment cavity extending along the leading edge and opening into the free end of the vane. The adjustment is carried out by inserting a first material into the adjustment cavity.

TECHNICAL FIELD OF THE INVENTION

The invention relates to the technical field of vanes for aircraft turbine engine, in particular fan vanes.

TECHNICAL BACKGROUND

The prior art is illustrated by the documents FR-A1-2906320, FR-A1-2962483, GB-A-2484726, FR-A1-2989991, FR-A1-3026033, FR-A1-3102378, US-A1-2014030106, US-A1-2014030107 and EP-A2-3812547.

As is well known, an aircraft turbine engine extends along a longitudinal axis and comprises, from upstream to downstream in the direction of gas flow, a fan, a low-pressure compressor and a high-pressure compressor, an annular combustion chamber, a high-pressure turbine and a low-pressure turbine and finally a gas exhaust nozzle.

The fan comprises a central disk rotating around an axis of rotation. The axis of rotation is, for example, the longitudinal axis of the turbine engine. The central disk is surmounted by a plurality of vanes for the initial compression of the air entering the turbine engine. The vanes are surrounded by a retaining casing which allows the vanes to be retained in the event of their breakage.

A fan vane is generally composed of a blade with an aerodynamic profile comprising a leading edge and a trailing edge joined by a pressure side and a suction side opposite the pressure side. The blade also comprises an upper end and an opposite lower end connected to a root. The root is designed to cooperate with a corresponding groove of the central disk to attach the vane to the central disk.

To reduce the weight of the fan, the blade of the vane is made from a composite material, typically an organic matrix composite (OMC). The composite material comprises a polymer matrix, for example a thermoplastic or thermosetting matrix, and fibres such as carbon fibres or glass fibres embedded in the matrix.

In addition, in order to protect the leading edge from erosive wear and/or damage caused by impact with foreign bodies, the leading edge is covered with a metal protective shield. The shield is assembled and glued to the leading edge. To do this, the leading edge or shield is coated with an adhesive layer, then the shield is assembled on the leading edge. The assembly is then subjected to heat treatment to ensure polymerisation of the adhesive layer. The shield is attached to the leading edge.

After manufacture, each vane is mounted on the central disk according to its own inertia and its relative inertia in relation to the neighbouring vanes. This meticulous mounting is referred to as “balancing”. Balancing the fan is essential to prevent rotation inducing a force perpendicular to the axis of rotation and prematurely wearing out the central disk and the turbine engine, as well as ensuring better efficiency and optimum performance.

To balance the fan, it is necessary to balance the forces generated by the vanes relative to the axis of rotation. The force generated by a vane is called the radial moment weight (RMW). The radial moment weight of a vane is equal to the mass of the vane multiplied by the distance between the center of gravity of the vane and the axis of rotation. When the radial moment weight of each vane is equal to that of the others, the rotor of the fan is perfectly balanced. The life of the rotor depends in part on how well it is balanced: the better balanced the rotor, the less wear and tear it suffers.

However, the manufacturing methods for the vanes result in a significant dispersion of the radial moment weight of the vanes. In order to balance the rotor perfectly, balancing flyweights have been known to be added to the cone of the module of the fan when the fan is mounted on the turbine engine. Without such balancing, an unbalance will occur and the rotor will wear out prematurely.

This solution is not entirely satisfactory in that it allows the radial moment weight to be adjusted on the entire set of vanes of the fan, i.e. after the fan has been mounted and not on the individual vanes before they are mounted. In addition, this solution involves the use of attached parts, which complicates the mounting of the fan.

As a result, there is a need to provide a method for limiting the radial moment weight dispersion of the vanes in order to facilitate the mounting of the fan whilst ensuring the balancing of the latter.

SUMMARY OF THE INVENTION

To this end, the invention proposes a method for correcting the radial moment weight of a vane for an aircraft turbine engine, the method comprising the following steps:(a) providing a vane extending along an axis of elongation Z between a free end opposite a root, the vane comprising a blade made of composite material having a leading edge, a trailing edge connected to the leading edge by a suction side and a pressure side opposite the suction side, the vane further comprising a protective shield attached to the leading edge,(b) measuring the radial moment weight of the vane,(c) comparing the measured radial moment weight with a reference value and adjusting the radial moment weight of the vane as a function of the result of the comparison.

The method is characterised in that, in step (a), the vane comprises at least one adjustment cavity extending along the leading edge and opening onto the free end of the vane, and in that, in the step, the adjustment is carried out by inserting a first material into the adjustment cavity.

According to the invention, the radial moment weight of the vane is first measured after manufacture and then compared with a reference value. The radial moment weight is then adjusted to match the reference value. In fact, the adjustment cavity allows the addition of at least one first material to adjust the radial moment weight of the vane. The radial moment weight of each vane can then be adjusted on a case-by-case basis, thereby limiting the dispersion of the radial moment weight of the vanes. This reduces the risk of creating an unbalance when mounting the vanes on the fan, and eliminates the need for additional balancing flyweights. In addition, the cavity is accessible via the end of the vane, which makes it easier to insert the first material when the vane is manufactured. Such a method also enables the radial moment weight of the vane to be adjusted precisely. The radial moment weight of the vane is measured at the end of the manufacturing phase of the vane, allowing the precise adjustment required to be determined.

The method according to the invention may comprise one or more of the following characteristics, taken alone or in combination with each other:in step (c) the adjustment is carried out by inserting a second material into the adjustment cavity, the density of the first material being different from the density of the second material;the first material is lead;the quantity of the first material is between 5 g and 50 g, and preferably between 10 g and 30 g;the adjustment cavity is formed in the protective shield;the protective shield comprises a first lateral fin extending over at least part of the suction side, a second lateral fin extending over at least part of the pressure side, a central portion connecting the first and second lateral fins and extending along the leading edge along the axis of elongation, the adjustment cavity being formed in the central portion;the adjustment cavity extends over the entire height of the leading edge along the axis of elongation;the vane comprises an adhesive layer disposed between the blade and the protective shield, the adjustment cavity being formed in the adhesive layer;step (a) comprises the following sub-step (a1): forming the adjustment cavity in the vane;at the end of sub-step (a1), the adjustment cavity has an upper longitudinal end opposite the root and a lower longitudinal end opposite the upper longitudinal end along the longitudinal axis which are closed, and in that the method comprises, after sub-step (a1), the following sub-step (a2): cutting or removing an end portion of the vane, opposite the root, so as to open the upper longitudinal end of the adjustment cavity.

DETAILED DESCRIPTION OF THE INVENTION

An aircraft turbine engine1is shown inFIG.1, for example. The turbine engine1extends along a longitudinal axis X. The turbine engine1comprises, from upstream to downstream in the direction of gas flow F, a fan2, a low-pressure compressor3, a high-pressure compressor4, at least one annular combustion chamber5, a high-pressure turbine6, a low-pressure turbine7and a gas exhaust nozzle (not shown).

The high-pressure turbine6comprises a rotor which rotates a rotor of the high-pressure compressor4via a high-pressure shaft8. The low-pressure turbine7comprises a rotor which rotates the rotor of the low-pressure compressor3and the fan2via a low-pressure shaft9.

The rotor of the fan2consists of a central disk2asurmounted by a plurality of vanes20evenly distributed around the circumference of the central disk2a. The disk2ais mobile in rotation about the longitudinal axis X. The vanes20of the fan2are, for example, surrounded by a retaining casing11designed to retain the vanes20in the event of their breakage. The retaining casing11has an internal surface coated with a layer of abradable material12. The layer of abradable material12is a layer that can be worn by friction with the vanes20. The vanes20according to the invention are therefore, for example, vanes20of the fan2.

As can be seen inFIG.2, the vane20comprises a blade21and a protective shield26. The blade21is secured to a root22, for example.

The vane20extends along an axis of elongation Z. The axis of elongation Z extends transversely to the longitudinal axis X of the turbine engine1. The vane20has a free end21aopposite the root22. The free end21afaces the abradable layer12. The root22cooperates with a corresponding groove (not shown) in the disk2ato attach the vane20to the disk2a.

The blade21is made of composite material. The composite material comprises a matrix and fibres embedded in the matrix. The composite material is, for example, an organic matrix composite (OMC). The matrix is, for example, a thermoplastic or thermosetting polymer matrix. The fibres are, for example, carbon fibres or glass fibres. For example, the fibres are organised in the form of a fibrous preform. The blade21is made, for example, by resin transfer moulding, injection moulding or draping.

The blade21has an aerodynamic profile. The blade21comprises a leading edge23and a trailing edge24joined by a suction side25aand a pressure side25bopposite the suction side25a.

The protective shield26is attached to the blade21. The protective shield26is made of metal, for example. The metallic material is titanium, for example.

The protective shield26has an elongated shape along the axis of elongation Z and extends along the blade21, and in particular along the leading edge23.

As can be seen inFIG.3, the protective shield26has a dihedral-shaped cross-section and comprises a first lateral fin26aand a second lateral fin26b. The first and second lateral fins26a,26bare connected by a central portion26c. The first lateral fin26aextends over at least part of the suction side25aand the second lateral fin26bextends over at least part of the pressure side25b. The central portion26ccovers the leading edge23. Advantageously, the central portion26chas, for example, a thickness e1as measured in a direction transverse to the axis of elongation Z greater than the thickness e2, e3respectively of the first and second lateral fins26a,26b. The first and second lateral fins26a,26bare tapered towards the trailing edge24of the blade21and fit snugly against the pressure side25band suction side25arespectively. The thicknesses e2, e3of the first and second lateral fins26a,26bdecrease towards the longitudinal ends of the protective shield26opposite the central portion26c.

In addition, as can be seen more clearly by way of example inFIG.5, the protective shield26comprises a receiving cavity29. The leading edge23is arranged in the receiving cavity29. The receiving cavity29extends along the leading edge23along the axis of elongation Z. The receiving cavity29is delimited laterally by the first and second lateral fins26a,26b. More particularly, the receiving cavity29is generally U-shaped or V-shaped. The receiving cavity29comprises a first wall formed by the first lateral fin26a, a second wall formed by the second lateral fin26band a transverse wall26dconnecting the first and second side walls. The protective shield26protects the leading edge23from external impact and wear, for example.

The protective shield26is attached to the blade21by gluing, for example. The vane20thus comprises an adhesive layer27arranged between the protective shield26and the blade21.

The adhesive layer27has a U-shaped cross-section. The adhesive layer27comprises a suction side fin27aarranged between the pressure side25aof the blade21and the first lateral fin26aof the protective shield26and a pressure side fin27barranged between the suction side25bof the blade21and the second lateral fin26bof the protective shield26. The adhesive layer27also comprises a central base27cconnecting the suction side fin27aand the pressure side fin27b. The central base27cis arranged between the leading edge23and the central portion26cof the protective shield26.

The central base27chas a first thickness e1′, as measured in a direction transverse to the axis of elongation Z, greater than the second and third thicknesses e2′, e3′ of the suction side and pressure side fins27a,27brespectively. The second and third thicknesses e2′, e3′ are advantageously identical.

The first thickness e1′ is, for example, between 1 mm and 10 mm. The second thickness e2′ is, for example, between 0.10 mm and 0.50 mm, preferably between 0.10 mm and 0.35 mm. The third thickness e3′ is advantageously identical to the second thickness e2′. The adhesive layer27is made, for example, of a polymeric material preferably chosen from epoxy resins. The polymeric material has a density of between 1 g/cm3 and 2 g/cm3, for example.

According to the invention, the vane20comprises at least one adjustment cavity28extending at least partly along the leading edge23, along the axis of elongation Z.

According to an advantageous embodiment of the invention, the adjustment cavity28extends over at least part of the height of the leading edge23along the axis of elongation Z. Preferably, the adjustment cavity28extends over the entire height of the leading edge23along the axis of elongation Z. The adjustment cavity28can therefore accommodate a larger quantity of material to precisely adjust its radial moment weight. The vane20is therefore balanced. The adjustment cavity28is closed at its longitudinal ends along the axis of elongation Z.

Advantageously, the vane20comprises at least a first material (not shown) arranged in the adjustment cavity28. The first material is, for example, powder. The quantity of the first material is advantageously between 5 g and 50 g, preferably between 5 g and 30 g, for example between 10 g and 30 g and even more preferably between 10 g and 20 g. The first material has a density of between 5 g/cm3and 15 g/cm3, for example. The first material is lead, for example. The first material is used to adjust the radial moment weight of the vane20.

In order to more accurately adjust the radial moment weight of the vane20, and/or to fill the remaining space of the adjustment cavity28to prevent movement of the first material therein, the vane20optionally comprises a second material (not shown) arranged in the adjustment cavity28. The second material has a different density to the first material. For example, the density of the second material is lower than the density of the first material. The quantity of the sum of the first and second materials is advantageously between 0 g and 20 g, preferably between 5 g and 20 g and even more preferably between 10 g and 20 g. The ratio between the weight of the first material and the second material is between 0 and 1.

The second material is polymeric, for example. The polymeric material is chosen from thermoplastics or thermosets, such as an epoxy-type resin. The second material is, for example, identical to the material of the adhesive layer27. This simplifies the manufacturing method, since the behaviour of the materials is identical.

In a first embodiment shown inFIG.4, the adjustment cavity28is formed in the protective shield26. For example, the adjustment cavity28is formed in the central portion26c. This allows the radial moment weight of the vane20to be adjusted without affecting the quality of bonding of the protective shield26to the blade21. Also, the central portion26chas a substantially elongated profile which makes it easy to have an adjustment cavity28along the entire length of the protective shield26and to reduce its torque master in order to preserve the mechanical properties of the protective shield26.

The adjustment cavity28has a central axis Y1parallel to the axis of elongation Z. The height H of the adjustment cavity28measured along its central axis Y1is advantageously between 100 mm and 500 mm, for example between 200 mm and 400 mm and preferably 350 mm. Preferably, the adjustment cavity28according to this example extends over the entire height of the vane20. The adjustment cavity28is partly delimited by the central portion26c.

As shown inFIG.6, for example, the adjustment cavity28has a trapezoidal cross-section. The trapezoid has a height L of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm, an internal base of length12, of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm, and an external base of length11, of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm. The lengths11and12may be different in order to adapt the shape of the adjustment cavity28to the geometry of the protective shield26, as shown, or of the same dimensions. According to an example not shown, the adjustment cavity28has a circular, elliptical, ovoid or polygonal cross-section.

In a second embodiment, shown for example inFIG.7, the adjustment cavity28is formed in the adhesive layer27. The adjustment cavity28is preferably inserted into the central base27c. In this embodiment, the adjustment cavity28is defined by an insert280. The insert280is hollow. The adjustment cavity28is located in the insert280. The insert280is arranged in the thickness of the adhesive layer27, preferably in the central base27c. In fact, the central base27cis subject to very little stress and makes only a small contribution to the bonding force of the protective shield26to the blade21, unlike the pressure side and suction side fins27a,27b. The addition of the insert280in this part of the adhesive layer27therefore has only a slight impact on the adhesive strength of the protective shield26on the blade21. The properties of the vane20are preserved. Thus, this embodiment, allows a vane20to be supplied with an adjustable radial moment weight without affecting its mechanical properties.

The insert280extends at least partly along the leading edge23along the axis of Elongation Z. The insert280extends between an upper longitudinal end28band an opposite lower longitudinal end28calong the axis of elongation Z. The insert280is cylindrical and elongated along an axis of revolution Y. The axis of revolution Y is parallel to the axis of elongation Z. The height H of the insert280in this embodiment, measured along the axis of revolution Y, is advantageously between 100 mm and 200 mm, for example between 150 mm and 200 mm. The insert280is made of polymeric material, for example. The polymeric material is chemically compatible with the material of the adhesive layer27.

In a first example of embodiment shown inFIG.7, the insert280has a circular cross-section. The internal diameter of the insert280is advantageously between 1 mm and 5 mm.

According to another example shown inFIG.8, the insert280has an elliptical cross-section. In this embodiment, the insert280has a large diameter L measured along the long axis, for example between 2 mm and 4 mm, and a small diameter I measured along the short axis, for example between 2 mm and 4 mm. The large diameter L is advantageously greater than the small diameter I.

A method for correcting the radial moment weight of the vane20will now be described with reference toFIGS.10and11.

The method comprises a first step (a) of supplying the vane20as described above. The step (a) of supplying the vane20may comprise the following sub-steps:(a00) supplying the blade21,(a01) supplying a protective shield26,(a02) applying the adhesive layer27,(a03) bonding the protective shield26to the blade21, and(a1) forming the adjustment cavity28in the vane20.

The sub-steps (a00) for supplying the blade21and (a01) for supplying the protective shield26can be carried out in parallel.

As illustrated inFIG.10, according to the first embodiment in which the adjustment cavity28is provided in the protective shield26, the sub-step (a1) of forming the adjustment cavity28is carried out during the sub-step (a01) of providing the protective shield26. For example, the protective shield26is formed by folding metal sheets and welding the transverse ends of the sheets around a support element to form the adjustment cavity28. The support element is fugitive, i.e., it is present during this sub-step but absent at the end of the step (a). The support element is therefore not present in the vane20.

As illustrated inFIG.11, according to the second embodiment in which the adjustment cavity28is formed in the adhesive layer27, the sub-step (a1) is advantageously carried out after the sub-step (a03) for bonding the protective shield26. In sub-step (a1) the insert280is arranged in the adhesive layer27. In this sub-step, the adjustment cavity28is closed at both its longitudinal ends. As illustrated inFIG.9, according to this second embodiment, after the sub-step (a1), the method comprises a sub-step (a2) of cutting or removing an end portion of the vane20, opposite the root22, so as to open the upper end of the adjustment cavity28opposite the root22. The cutting is carried out according to a cutting plane P transverse to the axis of revolution Y or the axis of elongation Z of the vane20.

In step (a), the adjustment cavity28opens onto the free end21aof the vane20. This configuration allows access to the adjustment cavity28after the vane20has been manufactured, making it easier to adjust its radial moment weight.

In a second step (b), the radial moment weight is measured.

In a third step (c), the radial moment weight measured in step (b) is compared with a reference value. This step determines the adjustment required to reach the reference value. The radial moment weight of the vane20is then adjusted according to the result of the comparison. According to the invention, the adjustment is carried out by inserting the first material into the adjustment cavity28.

Advantageously, the adjustment during step (c) is carried out by inserting the second material into the adjustment cavity28in combination with the first material. This enables the radial moment weight of the vane20to be adjusted more precisely by using materials of different densities. The insertion of the second material also allows the adjustment cavity28to be closed. A step of polymerisation of the second material can be carried out.

Thus, according to the invention, it is possible to adjust the radial moment weight of the vanes20individually during their manufacture. This allows this parameter to be homogenised during manufacture and avoids the creation of an imbalance on the rotor of the fan, for example after the mounting of the vanes20, resulting from a dispersion of the radial moment weight of the vanes20. For example, the radial moment weight of the vanes20can be adjusted by at least 5 g·cm, for example from 5 g·cm to 20 g·cm and for example 15g·cm.