FR3115570A1 - BLOWER HOUSING INCLUDING FIRE PROTECTION - Google Patents

Abstract

BLOWER HOUSING INCLUDING FIRE PROTECTION One aspect of the invention relates to a fan casing (3) for an aircraft turbine engine, said fan casing (3) having a cylindrical shape, comprising a radially outer surface (4) called the outer skin, the said outer skin (4 ) including a coat of anti-flammable paint. Figure to be published with abstract: Figure 3

Description

BLOWER HOUSING INCLUDING FIRE PROTECTION

TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of the protection against fire of a turbine engine for an aircraft and more particularly the protection against fire of a fan casing of the turbine engine.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

The fire resistance of an aircraft is a determining element for the safety on board the aircraft during a flight. The various components of the aircraft must be able to withstand fire for thirty minutes to two hours in order to provide operational stability allowing the pilot to initiate emergency procedures and land the aircraft. For example, following the start of a fire in one of the aircraft's turbomachines, it takes 5 minutes for the pilot to detect the incident and trigger an action; 5 minutes for the fire to stop as a result of the pilot's action; and an additional 20 minutes for the plane to land.

An inlet turbine of a turbomachine, called a fan, is intended to supply the turbomachine with fresh and compressed air. The fan can however receive solid debris which can damage the blades of the latter. Because of this debris, it is possible for a blade to detach from its axis. The fan comprises a casing, called the fan casing, one of the functions of which is to guarantee the retention of debris penetrating into the fan or the loss of the blades. However, an outer zone of the casing, also called the outer skin of the casing, is located in a fire zone.

The outer skin of the crankcase is covered with fire protection. It is a composite fabric comprising glass fibers, for example of the E1035 type, coated in an epoxy resin matrix, for example M26T. However, the composite fabric is complex to implement. For example, the laying of the composite fabric in the form of strips on the fan casing is carried out manually and many criteria must be respected, for example, the location, the length of the overlapping zones, called splints, the distance between two splints. During the laying of each strip 102, folds can form, as illustrated in the on a casing 100 according to the prior art, reducing the effectiveness of the protection. It is also difficult to cover the ridges or fillets 101. The composite fabric strips also require cross-linking in an oven in order to adhere to the casing and exhibit the thermal properties allowing protection against fire.

In the event of non-compliance, the repair, also called retouching, of the strips of composite fabric is also complex to implement and requires the use of a vacuum cover and a heating mat to carry out the reticulation of the retouchings.

The invention offers a solution to the problems mentioned above, by offering protection against fire which is easy to apply and repair, on flat surfaces and sharp angles.

One aspect of the invention relates to a fan casing for an aircraft turbomachine, said fan casing having a cylindrical shape, comprising a radially outer surface called the outer skin, the fan casing being noteworthy in that said outer skin comprises a coat of fireproof paint.

The radially inner surface is oriented towards the axis of symmetry of the cylindrical casing. The radially outer surface is opposed to the radially inner surface.

Paint, adhering to the outer skin of the casing, can reach edges and fillets, providing continuous fire protection over the entire surface of the fan casing.

• la peinture anti-inflammable est intumescente ;
• la peinture anti-inflammable déposée présente une épaisseur de dépôt ;
• la peinture anti-inflammable s'expand d'au moins quinze fois son épaisseur de dépôt lorsqu'elle est soumise à une température comprise entre 250 °C et 500 °C.
• l'épaisseur de dépôt de la couche de peinture anti-inflammable est comprise entre 1 et 2 mm ;
• la peau externe comprend une couche de vernis de protection sur la couche de peinture anti-inflammable ;
• une portion de la peau externe comprend un angle aigu ;
• la couche de peinture anti-inflammable est continue au niveau de l'angle aigu et localisée du côté étroit de l'angle aigu ;
• la couche de peinture anti-inflammable présente au moins une couleur prédéterminée.

In addition to the characteristics which have just been mentioned in the previous paragraph, the fan casing according to the invention may have one or more additional characteristics among the following, considered individually or according to all technically possible combinations:

• the anti-flammable paint is intumescent;
• the anti-flammable paint deposited has a deposit thickness;
• the anti-flammable paint expands by at least fifteen times its deposit thickness when subjected to a temperature between 250°C and 500°C.
• the thickness of the deposition of the layer of anti-flammable paint is between 1 and 2 mm;
• the outer skin includes a layer of protective varnish on the layer of anti-flammable paint;
• a portion of the outer skin includes an acute angle;
• the layer of anti-flammable paint is continuous at the level of the acute angle and located on the narrow side of the acute angle;
• the layer of anti-flammable paint has at least one predetermined color.

The invention also relates to a method for applying an anti-flammable paint to an outer skin of a fan casing for an aircraft turbomachine, the method of application being noteworthy in that it comprises a step of applying an anti-flammable paint to the outer skin so as to form a layer of anti-flammable paint on the outer skin.

The paint does not require cross-linking, so it is not necessary to have a means of heating, such as a large oven, in order to finalize the application of the anti-flammable paint on the fan casing .

Paint application is a process that can be automated. The automation of the anti-flammable paint application process offers better reproducibility than when it is carried out by an operator, thus making it possible to reduce the number of touch-ups to be carried out.

A second application of the paint can be carried out on the fan casing, at the level of a non-conformity, in order to carry out a touch-up of a first application of the paint. This type of touch-up can be done a large number of times, overlapping the applications each time.

The paint does not require splints so the thickness of the anti-flammable paint layer is constant over the entire outer skin.

• le procédé comprend une étape d'application d'une couche de vernis de protection sur la couche de peinture anti-inflammable ;
• l'étape d'application de la couche de peinture anti-inflammable est précédée par une étape de décapage ;
• l'application de la couche de peinture anti-inflammable sur la surface extérieure est réalisée au moyen d'un rouleau, d'une brosse ou par pulvérisation ;
• la peinture anti-inflammable est appliquée au niveau d'un angle aigu dans la peau externe.

In addition to the characteristics which have just been mentioned in the previous paragraph, the application method according to the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations:

• the method comprises a step of applying a layer of protective varnish on the layer of anti-flammable paint;
• the step of applying the anti-flammable paint layer is preceded by a stripping step;
• the application of the anti-flammable paint layer on the outer surface is carried out by means of a roller, a brush or by spraying;
• the flame retardant paint is applied at an acute angle in the outer skin.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

BRIEF DESCRIPTION OF FIGURES

The figures are presented for information only and in no way limit the invention.

schematically shows a fan casing according to the prior art, in sectional view, at the level of a fillet.

schematically presents an aircraft turbine comprising an embodiment of a fan casing according to the invention.

shows schematically, in section, the embodiment of the fan casing according to the invention.

schematically shows, in section, an enlargement of the fan casing at the level of a fillet.

schematically presents a mode of implementation of a method of applying the anti-flammable paint according to the invention.

schematically presents a first example of the fan casing during the implementation of the method of applying the anti-flammable paint according to the invention.

schematically presents a second example of the fan casing during the implementation of the method for applying the anti-flammable paint according to the invention.

DETAILED DESCRIPTION

The figures are presented for information only and in no way limit the invention. Unless specified otherwise, the same element appearing in different figures has a single reference.

• une turbine d'entrée 2, également appelée soufflante ; et
• un carter de soufflante 3, entourant la soufflante 2.

There schematically represents a turbine engine 1 intended to be mounted on an aircraft. The turbomachine 1 comprises:

• an inlet turbine 2, also called a fan; And
• a fan casing 3, surrounding the fan 2.

The fan casing 3 has a cylindrical shape aligned with the axis of rotation A of the fan 2. The casing 3 can be made of metal or of a composite material. An air intake sleeve 6 and an intermediate casing shroud 7 are arranged on either side of the fan casing 3 and in the extension of said fan casing 3. The fan casing 3 comprises a radially outer surface 4 and a radially inner surface 5. The radially outer surface 4 is also called the outer skin. The radially inner surface 5 is opposite the axis of rotation A of the fan 2.

In one embodiment of the fan casing 3 according to the invention, the outer skin 4 comprises protection against fire in the form of a layer of anti-flammable paint. The anti-flammable paint layer extends over a portion of the outer skin 4 or, preferably, over the whole of the outer skin 4.

The anti-flammable paint, unlike a composite fabric, exhibits good adhesion, in particular on metals and composites, making it possible to obtain a continuous and regular layer on the external skin 4. Thus, protection against the fire no longer presents the problems mentioned above such as a lack of protection at the level of the fillets or the formation of folds.

There schematically shows, in section, the embodiment of the fan casing 3. The top on the corresponds to the exterior e of the fan casing 3 while the bottom corresponds to the interior i of the fan casing 3. The fan casing 3 is coupled to the air intake sleeve 6 and to the casing shroud intermediate 7. Inside, the fan casing 3 has two acoustic panels 8 and 10 and a panel of abradable material 9. The anti-flammable paint layer extends over the outer surface 4, or outer skin 4, of the fan housing 3.

The anti-flammable paint layer may for example have a deposit thickness of between 1 mm and 2 mm. The protection against fire according to the prior art comprises two layers of composite fabric having a thickness of 0.3 mm each. Even if the deposition thickness of the anti-flammable paint layer according to the first embodiment is thicker, the density of the anti-flammable paint is lower than the density of the composite fabric. Thus, the weight of the anti-flammable paint layer is of the same order of magnitude as the weight of the protection against fire according to the prior art.

Advantageously, the anti-flammable paint is intumescent, ie it swells (or expands) when its temperature exceeds a threshold temperature. Intumescent paint is a product that can be used in construction for fire protection. The intumescent paint is, for example, a thermoplastic product whose threshold temperature is between 250°C and 300°C. The thickness of the intumescent paint layer subjected to a heat flux, such as a flame, can increase by at least fifteen times its deposit thickness when its temperature exceeds the threshold temperature, forming a microporous foam also called meringue. The meringue has a high thermal resistivity, making it possible to thermally insulate the fan casing 3 from the heat flow and thus slowing down the heating of said fan casing 3. The intumescent paint makes it possible to slow the spread of fire in the turbomachine 1.

Preferably, the layer of intumescent paint is protected by a layer of protective varnish.

There schematically shows an enlargement of the casing 3 at the level of a fillet, formed for example at the level of a flange. The outer skin 4 at the fillet forms an acute angle, for example between 10° and 90°, in this case equal to 90°. Unlike the protection against fire according to the prior art, the layer of anti-flammable paint according to the invention extends continuously and lines the inside of the acute angle, on the narrow side of the acute angel. Thus, the continuity of the layer of the fire protection layer is improved.

The anti-flammable paint can have a predetermined color. The choice of a color contrasting with the color of the raw outer skin 4 makes it possible, for example, to visually discriminate the holes in the layer of paint. It is also possible to use two anti-inflammable paints each having a predetermined color, allowing for example to paint alignment or informative patterns in order to facilitate the assembly of the fan casing 3 within the turbomachine 1.

FIGS. 5 and 6 present a first mode of implementation of a method of applying the layer of anti-flammable paint to the outer skin 4 of the fan casing 3. According to this first mode of implementation, the application method 20 comprises a step of applying anti-flammable paint 22 to the outer skin 4 so as to form the layer of anti-flammable paint.

The paint layer can for example be applied by means of rollers, brushes or by spraying, as presented schematically in the . In the , the paint is applied by means of two paint guns 11, 12, spraying the paint in a uniform layer on the external skin 4. A first gun 11 sprays the paint on a portion of the external skin 4 and on a flange of the casing of blower 3. A second gun 12 sprays the paint on the rest of the outer skin 4. The paint, when it is in the liquid state, is wetting and can be deposited on any type of shape, such as edges or holidays, as for example illustrated in the . The application of anti-flammable paint 22 therefore makes it possible to protect elements whose shapes are varied, such as a flange.

The application of the anti-flammable paint 22 is simple in particular in that it does not require the use of splints or cross-linking. Concerning this last point, it is therefore not necessary to have a means of heating, such as a large oven, in order to finalize the application of the paint on the fan casing 3.

The application of the anti-flammable paint 22 can be automated. The automation of the application 22 offers better reproducibility than when it is carried out by an operator, thus making it possible to reduce the retouching to be carried out.

In order to protect the layer of anti-flammable paint, the application process 20 can also comprise the application of a layer of protective varnish 23 on the layer of anti-flammable paint. The protective varnish layer can also be applied by means of rollers, brushes or by spraying.

The application process 20 makes it possible to carry out repairs or touch-ups on the fan casing 3 whose anti-flammable paint layer is not compliant. It may for example be a hole in the coat of paint due to a defect during the application step 22. It may also be a hole made in the casing 3 after a first production of the application step 22. Unlike the touch-ups carried out on the protection against fire according to the prior art, a touch-up of anti-flammable paint only requires carrying out the step of applying the paint again 22 at the level of non-compliance. Touch-ups can be carried out several times without degrading the level of protection of the fan casing 3.

A mask 13 can be arranged around the nonconformity, as illustrated in the , in order to apply the anti-flammable paint only at the level of non-compliance.

In order to improve the hold of the anti-flammable paint on the outer skin 4, or to remove a layer of paint or varnish already present, the application method 20 may comprise a step of stripping the outer skin 21. The step of stripping the outer skin 21 precedes the step of applying the paint 21. The stripping step 21 can be carried out mechanically, for example by means of an abrasive tool, or chemically. To carry out a touch-up at the level of a non-conformity, it may be necessary to carry out the stripping step 21 at the level of the non-conformity, thus making it possible to deposit the anti-flammable paint on a portion of external skin 4 that is clean .

Claims (7)

Fan casing (3) for an aircraft turbomachine (1), said fan casing (3) having a cylindrical shape, comprising a radially outer surface (4) called the outer skin, the fan casing (3) being characterized in that said outer skin (4) comprises a layer of anti-flammable paint. Fan casing (3) according to the preceding claim, in which the anti-flammable paint is intumescent. Fan casing (3) according to the preceding claim, in which the anti-flammable paint deposited has a thickness of deposit, in which the anti-flammable paint expands by at least fifteen times its thickness of deposit when it is subjected at a temperature between 250°C and 500°C. Fan casing (3) according to any one of the preceding claims, in which the thickness of the deposit of the layer of anti-flammable paint is between 1 and 2 mm. Fan casing (3) according to any one of the preceding claims, in which the outer skin (4) comprises a layer of protective varnish on the layer of anti-flammable paint. Fan casing (3) according to any one of the preceding claims, in which a portion of the outer skin (4) comprises an acute angle, the layer of anti-flammable paint being continuous at the level of the acute angle and located on the narrow side of the acute angle. Method of applying (20) a layer of anti-flammable paint on an outer skin (4) of a fan casing (3) for an aircraft turbine engine (1), the method of application (20) being characterized in that it comprises a step of applying an anti-flammable paint (22) to the external skin (4) so as to form a layer of anti-flammable paint on the external skin (4).