Ventilation grille for turbomachine nacelle
The intumescent-coated ventilation grille addresses airflow inefficiencies at low speeds by obstructing during fires, enhancing cooling efficiency and safety without increasing size, thus optimizing nacelle ventilation systems.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-12-09
- Publication Date
- 2026-06-12
AI Technical Summary
The positioning constraint of ventilation grilles on turbomachine nacelles limits their effectiveness during low or zero aircraft speed due to insufficient airflow, and existing solutions to address this issue increase the system's bulk, compromising space efficiency.
A ventilation grille with intumescent material-coated blades and frame parts that obstruct air passages upon exceeding a specific temperature, allowing flexible positioning and enhancing airflow efficiency without increasing size.
The intumescent material obstructs air passages during fires, preventing flame ingress and improving cooling efficiency, especially at low speeds, while maintaining compactness and safety.
Smart Images
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Abstract
Description
Title of the invention: Ventilation grille for turbomachine nacelle. Technical field
[0001] The present invention relates to the field of turbomachinery. It relates more particularly to the ventilation of a turbomachine nacelle. Previous technique
[0002] Turbomachine nacelles are usually equipped with a ventilation system for the turbomachine compartments to ensure a sufficiently cool thermal environment compatible with the operation of the turbomachine components in nominal mode. Indeed, overheating can lead to the deterioration or even the breakage 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 to be cooled, and then exits the nacelle through an outlet including a grille also present 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 the wing, to prevent flames or excessive heat from damaging these structural parts. Therefore, the grille is generally positioned at the 6 o'clock position on the nacelle, clockwise, which is approximately vertical 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 idles or engine shutdowns. Indeed, during ground idles or engine shutdowns, 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," tends to push air from the grille towards the scoop, which in some cases can considerably reduce, or even eliminate, the airflow through 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 means. However, the addition of a cover and a triggering device This increases the bulk of the ventilation system, while the space available in the gondola 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 obstructed 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, thus allowing it to be positioned close to the aircraft's structural components. This makes it possible, in particular, to position the ventilation grille at the 12 o'clock position, i.e., at the same angular position on the nacelle as the scoop, thereby promoting airflow from the scoop to the grille by convection. The freedom in positioning the grille then makes the nacelle cooling system more efficient, especially at low or zero aircraft speed. 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, these two events occurring simultaneously when it is subjected to a temperature above its expansion temperature.
[0012] According to a particular feature, the intumescent material coating is present on one face of each blade of the plurality of blades opposite an adjacent blade or part of the frame. This feature makes it possible to minimize the quantity of intumescent material used for an air passage orifice while ensuring sufficient obstruction of the grid when required.
[0013] According to another particular 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 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 the blockage of the air passage openings 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 feature ensures grid obstruction beyond the expansion temperature for a relatively thin coating, thereby limiting the impact of the intumescent coating on the grid's airflow. The invention is thus easily adaptable to existing grids.
[0015] According to another particular characteristic, the intumescent material preferably has an expansion pressure of at least 20 bar. This makes it possible to improve the speed of intervention in the event of a fire.
[0016] According to another particular feature, the intumescent material preferably has an expansion temperature greater than or equal to 200°C. This makes it possible to avoid an unexpected obstruction of the ventilation grille with respect to the nominal temperatures and / or permissible overheating 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] Fig. 1 is a schematic cross-sectional view of a gondola of a turbomachine,
[0020] [Fig.2] Fig.2 is a schematic cross-sectional view of a ventilation grille according to one embodiment of the invention,
[0021] [Fig.3] The [Fig.3] is a schematic cross-sectional view of the grid of the [Fig.2] during a fire in a nacelle compartment. Description of the implementation methods
[0022] The invention is now described by means of figures, which are present 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, in a known manner, a fan 110 and an engine section comprising successively 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 comprises 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 inner face and the outer face, an internal compartment 173, in which are housed equipment such as electronic accessory boxes, pumps and oil and fuel tanks, and others (not shown).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, for example, be 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 frame portion 210a, on one face of the blade 220b opposite the blade 220a, on one face of the blade 220c opposite the blade 220b, and on the frame portion 210b opposite the blade 220c. Thus, at least a portion of the contour of each air passage 230a to 230d comprises an intumescent material coating. This limits the amount of intumescent material used.
[0027] According to a particular feature of the invention, the entire contour 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 capacity to increase its volume (expansion) significantly when subjected to heat. Once expanded, the material does not burn and forms a crust that also provides thermal insulation. Thus, when the temperature rises above the expansion temperature of the intumescent material, the ventilation grille is obstructed. This makes it possible to isolate the aircraft's structural parts 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, obstructing the ventilation grille increases this concentration.
[0029] Fig. 2 illustrates the ventilation grille in nominal operation, i.e. in the absence of a fire in compartment 173. In this configuration, the air passage orifices 230 are fully open so that the 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 above its expansion temperature. Its volume increases so as to obstruct the air passages 230a to 230d as illustrated in [Fig.3].
[0031] According to a particular feature of the invention, the intumescent material 240 preferably has an expansion temperature 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 the company Promat, intumescent strips marketed by Würth, PALUSOL® marketed by Odice, Tramifeu® marketed by Tramico, intumescent strips marketed by KFIRE, Expantrol® marketed by 3M, FIPW marketed by Fischer, Intustrap® marketed by Nullifire.
Claims
Demands
1. Ventilation grille (200) of a nacelle (170) of a turbomachine (100) comprising a frame (210) and a plurality of blades (220) extending inside the frame (210), the blades (220) of the plurality of blades delimiting with each other or with a part (210a, 210b) of the frame air passage orifices (230), characterized in that at least a part (210b) of the frame (210) or a blade (220) of the plurality of blades defining each air passage orifice (230) comprises a coating of intumescent material (240) capable of obstructing the air passage orifice (230) beyond an expansion temperature of said intumescent material.
2. Ventilation grille according to claim 1, wherein the intumescent material coating (240) is present on one face of each blade (220) of the plurality of blades opposite an adjacent blade or part (210b) of the frame (210).
3. Ventilation grille according to claim 1 or 2, 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.
4. Ventilation grille according to any one of claims 1 to 3, wherein the intumescent material (240) has an expansion ratio of at least 1:
20.
5. Ventilation grille according to any one of claims 1 to 4, wherein the intumescent material (240) has an expansion pressure of at least 20 bars.
6. Ventilation grille according to any one of claims 1 to 5, wherein the intumescent material (240) has an expansion temperature greater than or equal to 200°C.
7. Turbomachine nacelle comprising at least one ventilation grille according to any one of claims 1 to 6.
8. Aircraft comprising at least one nacelle (170) according to any one of claims 1 to 7.