Ventilation grille for turbine engine nacelle

Abstract

The invention relates to a ventilation grille (200) of a turbine engine nacelle, the grille comprising a frame (210) and a plurality of slats (220) extending within the frame, the slats (220) of the plurality of slats delimiting, between themselves or with a portion (210a, 210b) of the frame, openings (230) for air to pass through. At least a portion (210b) of the frame (210) or a slat (220) of the plurality of slats defining each opening (230) for air to pass through comprises a coating made of an intumescent material (240) designed to block the opening (230) for air to pass through once the intumescent material reaches its expansion temperature.

Description

Description Title of the invention: Ventilation grille for turbomachine nacelle Technical Field

[0001] The present invention relates to the field of turbomachinery. More particularly, it relates to the ventilation of a turbomachine nacelle. Previous technique

[0002] Turbomachine nacelles are typically equipped with a ventilation system for the turbomachine compartments to ensure a sufficiently cool thermal environment compatible with the operation of the turbomachine components under nominal conditions. Overheating can lead to the deterioration or even failure of certain parts.

[0003] It is therefore common to implement air circulation through the nacelle, for example through the blower compartment and the central compartment. Outside air enters the compartment to be cooled through an inlet on the nacelle called a "scoop," circulates within the compartment, and then exits the nacelle through an outlet with a grille, also located on the nacelle.

[0004] The positioning of the grille on the nacelle is limited due to safety constraints in the event of an engine fire. The grille must be positioned away from structural parts of the aircraft, such as the pylon or wing, to prevent flames or excessive heat from damaging these components. Therefore, the grille is generally positioned at the 6 o'clock position on the nacelle, clockwise, and roughly vertically at the bottom.

[0005] This positioning constraint limits the effectiveness of nacelle cooling at low or zero speed, which is particularly the case during ground idling or engine shutdown. Indeed, during ground idling or engine shutdown, the aircraft's speed is insufficient to force airflow through the scoop. This results in a situation where the thermal draft effect, known as the "chimney effect," has tendency to push air from the grille towards the scoop, which in some cases can significantly reduce, or even cancel, the airflow circulating in the nacelle.

[0006] US patent 2022 / 065130 describes a turbomachine turbine ventilation device in which the air outlet grille can be closed by a cover when the temperature inside a nacelle compartment exceeds a predetermined temperature. The cover is actuated by melting a locking mechanism. However, adding a cover and a triggering device increases the overall size of the ventilation system, while the available space in the nacelle compartments is already very limited.

[0007] It would therefore be desirable to have a solution allowing greater freedom in positioning the grid without a significant increase in size. Description of the invention

[0008] To this end, the present invention proposes a ventilation grille for a turbomachine nacelle comprising a frame and a plurality of blades extending inside the frame, the blades of the plurality of blades delimiting air passage orifices between themselves or with a part of the frame, characterized in that at least a part of the frame or a blade of the plurality of blades defining each air passage orifice comprises a coating of intumescent material capable of obstructing the air passage orifice beyond an expansion temperature of said intumescent material.

[0009] The invention thus proposes a ventilation grille which can be blocked in the event of a fire in a nacelle compartment, without increasing the size of the nacelle ventilation system.

[0010] Such a ventilation grille also has the advantage of preventing flames from entering in the event of a fire, allowing it to be positioned close to the aircraft's structural components. This notably allows the ventilation grille to be placed at the 12 o'clock position, i.e., in the same angular position on the nacelle as the scoop, thus promoting airflow from the scoop to the grille by convection. The freedom to position the grille allows for more efficient nacelle cooling, particularly at low or zero aircraft speeds. Thus, the present invention also simplifies the ventilation circuits of the nacelle compartments.

[0011] In this application, unless explicitly stated otherwise, "intumescent material" means a material that reaches an expansion rate of at least 10% and an expansion pressure of at least 1 bar when subjected to a temperature above its expansion temperature. This expansion of the intumescent material occurs at a constant amount of substance. Thus, the expansion of the intumescent material corresponds to a decrease in its density and an increase in its volume, both of which occur simultaneously when it is subjected to a temperature above its expansion temperature.

[0012] According to a specific feature, the intumescent material coating is present on one face of each blade in the plurality of blades opposite an adjacent blade or part of the frame. This feature minimizes the amount of intumescent material used for an air passage opening while ensuring sufficient grid obstruction when required.

[0013] According to another specific feature, the intumescent material coating is present on each face of each blade in the plurality of blades and on each part of the frame opposite a blade. This feature increases the speed at which air passages become blocked in the event of a fire and / or ensures that air passages are blocked when the expansion rate of the intumescent material is insufficient to cover the distance between two blades or between a part of the frame and a blade.

[0014] According to another particular feature, the intumescent material preferably has an expansion ratio of at least 1:20. This characteristic ensures grid obstruction beyond the expansion temperature for a relatively thin coating, thus limiting the impact of the intumescent coating on the grid's airflow. The invention is therefore easily adaptable to existing grids.

[0015] Another key characteristic is that the intumescent material preferably has an expansion pressure of at least 20 bar. This improves the speed of intervention in the event of a fire.

[0016] According to another specific characteristic, the intumescent material preferably has an expansion temperature of 200°C or higher. This prevents unexpected obstruction of the ventilation grille with respect to the nominal and / or permissible overheating temperatures in the nacelle compartment.

[0017] The invention also relates to a turbomachine nacelle comprising at least one ventilation grille according to one of the preceding particular characteristics.

[0018] The invention also relates to an aircraft comprising at least one nacelle according to one of the preceding particular characteristics. Brief description of the drawings

[0019] [Fig. 1] Figure 1 is a schematic cross-sectional view of a turbomachine nacelle,

[0020] [Fig. 2] Figure 2 is a schematic cross-sectional view of a ventilation grille according to one embodiment of the invention,

[0021] [Fig. 3] Figure 3 is a schematic cross-sectional view of the grid in Figure 2 during a fire in a gondola compartment. Description of the implementation methods

[0022] The invention is now described by means of figures, which are provided for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0023] Figure 1 schematically illustrates a turbomachine 100 comprising, as is known, a fan 110 and an engine section comprising successively comprises at least one low-pressure compressor stage 120, at least one high-pressure compressor stage 130, a combustion chamber 140, at least one high-pressure turbine stage 150, and at least one low-pressure turbine stage 160. The turbomachine 100 also includes a nacelle 170. The nacelle 170 has an annular shape and defines an annular flow channel for a secondary flow. The nacelle 170 has an internal surface 170a defining said annular flow channel and an external surface 170b in contact with the ambient air. The nacelle includes, between the internal and external faces, an internal compartment 173, in which equipment such as electronic accessory boxes, oil and fuel pumps and reservoirs, and other components (not shown) are housed. The nacelle 170 is further equipped with a ventilation system comprising an air inlet 171 and an air outlet 172 located on the external surface 170b of the nacelle.The air inlet 171 can be, for example, a scoop through which cooling air can enter the compartment 173. After circulating in the compartment 173, the cooling air is expelled through the air outlet 172 which includes a ventilation grille 200.

[0024] Figure 2 schematically illustrates a ventilation grille 200 according to an embodiment of the invention. The ventilation grille 200 comprises a frame 210 and a plurality of blades 220 extending inside the frame, the blades defining air passage openings 230 between themselves or with a portion of the frame. In the example described here, the ventilation grille 200 comprises three blades 220a, 220b and 220c and four air passage openings 230a, 230b, 230c and 230d defined respectively between a first portion of the frame 210a and blade 220a, between blade 220a and blade 220b, between blade 220b and blade 220c and between blade 220c and a second portion of the frame 210b.

[0025] According to the invention, an intumescent material coating 240 is present on a blade and / or part of the frame defining each air passage orifice 230, the intumescent material being capable of obstructing the air passage orifice beyond an expansion temperature of said intumescent material.

[0026] In the example described here, a layer of intumescent material 240 is present on one face of the blade 220a opposite the part of the frame 210a, on a face of blade 220b opposite blade 220a, on one face of blade 220c opposite blade 220b, and on the portion of frame 210b opposite blade 220c. Thus, at least a portion of the contour of each air passage 230a to 230d has an intumescent material coating. This limits the amount of intumescent material used.

[0027] According to a particular feature of the invention, the entire perimeter of each air passage opening can be covered with the intumescent material coating. In the example described here, this corresponds to the presence of the intumescent material coating on the frame sections 210a and 210b, as well as on both faces of each of the blades 220a, 220b, and 220c. This makes it possible to increase the rate at which the air passage openings become blocked in the event of a fire and / or to ensure that the air passage openings are blocked when the expansion rate of the intumescent material is insufficient to cover the distance between two blades or between a frame section and a blade.

[0028] An intumescent material has the ability to expand significantly when exposed to heat. Once expanded, it does not burn and forms a crust that also provides thermal insulation. Therefore, when the temperature rises above the intumescent material's expansion temperature, the ventilation grille is blocked. This makes it possible to isolate the aircraft's structural components from the flames and extinguish a fire by smothering. Furthermore, the use of an intumescent material optimizes the efficiency of fire extinguishing cylinders and, consequently, their size, which depends on the concentration of extinguishing agent in the compartment. Indeed, blocking the ventilation grille increases this concentration.

[0029] Figure 2 illustrates the ventilation grille in nominal operation, i.e. in the absence of fire in compartment 173. In this configuration, the air passage orifices 230 are fully open so that outside air introduced via the air inlet 171 is ejected via the ventilation grille 200 after circulating in compartment 173.

[0030] When a fire breaks out, the intumescent material 240 is subjected to a temperature higher than its expansion temperature. Its volume increases, obstructing the air passages 230a to 230d as illustrated in Figure 3.

[0031] According to a particular feature of the invention, the intumescent material 240 has an expansion temperature preferably greater than or equal to 200°C. This prevents unexpected obstruction of the ventilation grille 200 with respect to the nominal and / or permissible overheating temperatures in the nacelle compartment 173. By way of non-limiting example, the expansion temperature is between 200°C and 300°C for the blower compartment and between 350°C and 450°C for the central compartment.

[0032] The intumescent material can be chosen from one of the following materials: Promaseal® marketed by Promat, intumescent tapes marketed by Würth, PALUSOL® marketed by Odice, Tramifeu® marketed by Tramico, intumescent tapes marketed by KFIRE, Expantrol® marketed by 3M, FIPW marketed by Fischer, Intustrap® marketed by Nullifire.

Claims

Demands [Claim 1] A ventilation grille (200) for a turbomachine (100) nacelle (170) comprising a frame (210) and a plurality of blades (220) extending within the frame (210), the blades (220) of the plurality of blades delimiting air passages (230) with each other or with a portion (210a, 210b) of the frame, characterized in that at least a portion (210b) of the frame (210) or a blade (220) of the plurality of blades defining each air passage (230) comprises an intumescent material coating (240) capable of obstructing the air passage (230) beyond an expansion temperature of said intumescent material, the intumescent material coating (240) being present on one face of each blade (220) of the facing plurality of blades of an adjacent blade or part (210b) of the frame (210). [Claim 2] Ventilation grille according to claim 1, wherein the intumescent material coating (240) is present on each face of each blade (220) of the plurality of blades and on each part (210a, 210b) of the frame opposite a blade. [Claim 3] Ventilation grille according to claim 1 or 2, wherein the intumescent material (240) has an expansion ratio of at least 1:

20. [Claim 4] Ventilation grille according to any one of claims 1 to 3, wherein the intumescent material (240) has an expansion pressure of at least 20 bars. [Claim 5] Ventilation grille according to any one of claims 1 to 4, wherein the intumescent material (240) has an expansion temperature greater than or equal to 200°C. [Claim 6] Turbomachine nacelle comprising at least one ventilation grille according to any one of claims 1 to 5. [Claim 7] Aircraft comprising at least one nacelle (170) according to any one of claims 1 to 6.

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