Patent Publication Number: US-2022219029-A1

Title: Aircraft propulsion assembly having a ventilation system and a fire-fighting system

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of the French patent application No. 2100337 filed on Jan. 14, 2021, the entire disclosures of which are incorporated herein by way of reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an aircraft propulsion assembly having two fairing devices, a ventilation system ensuring the ventilation of compartments that are delimited inside each fairing device and a fire-fighting system. 
     The invention also relates to an aircraft equipped with such a propulsion assembly. 
     BACKGROUND OF THE INVENTION 
     Throughout the present description, the “upstream” and “downstream” directions are defined relative to the overall direction of the flow of the gases in the turbomachine, and the terms “front” and “rear” are to be considered relative to a direction F of forward movement of the aircraft under the effect of the thrust produced by the turbine engine, this direction being parallel to a longitudinal axis X of the propulsion assembly and of the turbine engine. 
       FIG. 8  shows an axial section of a propulsion assembly  500  of the prior art that has a turbofan  102  with a fan  103  and an outer fairing device  104  that surrounds the turbofan  102 . 
     The outer fairing  104  has an external annular wall  106  and an internal annular wall  108 . The external annular wall  106  forms an outer fairing along which the outside air flows. The internal annular wall  108  channels an incoming flow of air  50  that supplies the turbofan  102  and is divided downstream of the fan  103  into a primary flow  52  and a secondary flow  54 . 
     The primary flow  52  flows inside the core  110  that, in this case, has, in succession, in the direction of flow of the primary flow  52 , a compression chamber, a combustion chamber, and a turbine chamber. The primary flow  52  is evacuated via the jet pipe  70 . 
     The secondary flow  54  flows around the core  110  in a secondary duct  72  and the primary flow  52  flows inside the core  110  in a primary duct  73 . 
     The external annular wall  106  and internal annular wall  108  delimit between them an outer compartment  112  of the outer fairing device  104 , also called “fan compartment”, which is positioned between an air intake  114  and a thrust reverser  116 . 
     This outer compartment  112  contains equipment, some of which has to be ventilated and thus kept under a determined temperature. 
     In order to ensure the ventilation of the outer compartment  112  and of the equipment possibly housed therein, the outer fairing device  104  has an air intake orifice  530  and an air exhaust orifice  532  that are formed in the external annular wall  106  of the outer compartment  112 . These two orifices  530  and  532  are in general diametrically opposite one another relative to the longitudinal axis X. The air intake orifice  530  generally takes the form of a scoop that allows the outside air to be drawn into the outer compartment  112  and the air exhaust orifice  532  generally takes the form of a grill that allows the air to be drawn towards the outside. 
     The flow of air thus admitted into the outer compartment  112  then forms a ventilation flow circulating in the outer compartment  112  so as to end up leaving the latter through the air exhaust orifice  532  and thus ventilate and cool the inside of the outer compartment  112  and the equipment present. 
     On the inside, the secondary flow  54  flows along an inner fairing device  134  comprising an external annular wall  136  and an internal annular wall  138  that delimit between them an inner compartment  140 , commonly called “core compartment”, and the external annular wall  136  is sometimes called “IFS” (“Inner Fixed Structure”). 
     The secondary duct  72  is delimited between the external annular wall  136  of the inner fairing  134  and the internal annular wall  108  of the outer fairing  104 . The primary duct  73  is delimited inside the internal annular wall  138  of the inner fairing  134 . 
     As before, the inner compartment  140  has to be ventilated and, to this end, the external annular wall  136  has one or more air intake apertures  542  and one or more air exhaust apertures  544  that are distributed about the longitudinal axis X. Each air intake aperture  542  allows the air of the secondary flow  54  to be admitted into the inner compartment  140  and each air exhaust aperture  544  allows the air of the inner compartment  140  to be rejected towards the outside. 
     As is the case for the orifices  530  and  532 , the apertures  542  and  544  take, for example, the form of scoops or an annular opening. 
     This passive ventilation mode gives good results. However, when cruising, the supply of fresh air can be excessive relative to the actual needs, and during the taxiing phases, the supply of fresh air can be insufficient. To remedy the latter point, the orifices can be sized in accordance with this taxiing phase, and this will give rise to over-ventilation of the compartments in flight and lead to additional fuel consumption. 
     Furthermore, in the event of a fire, it is known to put in place a fire-fighting system that has a reservoir containing an extinguishing fluid and pipes that make it possible to channel the extinguishing fluid from the reservoir towards the outer compartment  112  and the inner compartment  140 . The extinguishing fluid is generally the product known under the name “Halon”. To comply with environmental requirements, Halon has to be replaced with new extinguishing fluids that require larger storage volumes for an effectiveness equivalent to Halon. 
     It is therefore desirable to find an arrangement that makes it possible to ensure the ventilation in the compartments, while optimizing the intake flow rates for the actual needs in terms of ventilation of each flight phase, and that is associated with a more compact fire-fighting system. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to propose a propulsion assembly for an aircraft, which has two fairing devices and a ventilation system ensuring the ventilation of compartments that are delimited inside each fairing device. 
     To that end, there is proposed a propulsion assembly for an aircraft and the propulsion assembly has:
         a primary duct and a secondary duct,   an outer fairing having an external annular wall and an internal annular wall that delimit between them an outer compartment, wherein the external annular wall has an inlet opening,   an inner fairing having an external annular wall and an internal annular wall that delimit between them an inner compartment, wherein the external annular wall has at least one air exhaust aperture,       

     wherein the secondary duct is delimited between the internal annular wall of the outer fairing and the external annular wall of the inner fairing, 
     wherein the primary duct is delimited inside the internal annular wall of the inner fairing, 
     said propulsion assembly being characterized in that it also has:
         a suction system having an inlet, an outlet and mobile elements that are designed to draw air in via the inlet and deliver the drawn-in air via the outlet,   a drive means designed to drive the mobile elements,   a transfer pipe fluidically connected to the outlet of the suction system,   a distribution pipe disposed in the inner compartment, fluidically connected to the transfer pipe and having a plurality of nozzles,   a supply pipe of which one end opens into the outer compartment and of which the other end is fluidically connected to the inlet of the suction system,   a regulating means arranged so as to regulate the flow rate of air in the suction system, and   a fire-fighting system having a reservoir containing an extinguishing fluid, a discharge pipe of which a first end is fluidically connected to the reservoir, and a control system interposed between the reservoir and the discharge pipe that alternately adopts a closed position preventing the extinguishing fluid from flowing into the discharge pipe or an open position allowing the extinguishing fluid to flow into the discharge pipe, and wherein a second end of the discharge pipe opens directly into the transfer pipe so as to supply it, when the control system is in the open position.       

     To that end, there is also proposed a propulsion assembly for an aircraft and the propulsion assembly has:
         a primary duct and a secondary duct,   an outer fairing having an external annular wall and an internal annular wall that delimit between them an outer compartment, wherein the external annular wall has an inlet opening,   an inner fairing having an external annular wall and an internal annular wall that delimit between them an inner compartment, wherein the external annular wall has at least one air exhaust aperture,       

     wherein the secondary duct is delimited between the internal annular wall of the outer fairing and the external annular wall of the inner fairing, 
     wherein the primary duct is delimited inside the internal annular wall of the inner fairing, 
     the propulsion assembly being characterized in that it also has:
         a suction system having an inlet, an outlet and mobile elements that are designed to draw air in via the inlet and deliver the drawn-in air via the outlet,   a drive means designed to drive the mobile elements,   a transfer pipe fluidically connected to the outlet of the suction system,   a distribution pipe disposed in the inner compartment, fluidically connected to the transfer pipe and having a plurality of nozzles,   a supply pipe of which one end opens into the outer compartment and of which the other end is fluidically connected to the inlet of the suction system,   a regulating means arranged so as to regulate the flow rate of air in the suction system, and   a fire-fighting system having a reservoir containing an extinguishing fluid, a discharge pipe of which a first end is fluidically connected to the reservoir, and a control system interposed between the reservoir and the discharge pipe that alternately adopts a closed position preventing the extinguishing fluid from flowing into the discharge pipe or an open position allowing the extinguishing fluid to flow into the discharge pipe, and wherein a second end of the discharge pipe opens directly into the outer compartment so as to supply the transfer pipe, when the control system is in the open position.       

     In each of these two embodiments, the outside air is then driven by the suction system and passes through the two compartments in a forced manner and the fire-fighting system uses the transfer pipe and the distribution pipe to diffuse the extinguishing product within the compartments in question. The flow rate of ventilation in the compartments in question in the event of a fire is then significant and the quantity of extinguishing product can therefore be smaller for the same effectiveness since this significant flow rate allows a rapid and highly concentrated supply of the extinguishing product. 
     Advantageously, the fire-fighting system also has a discharge sub-pipe of which a first end opens into the discharge pipe and of which a second end opens into the outer compartment. 
     Advantageously, the control system has a first control sub-system and a second control sub-system, wherein the first control sub-system controls the flow of the extinguishing fluid into the discharge pipe and wherein the second control sub-system controls the flow of the extinguishing fluid into the discharge sub-pipe. 
     The invention also proposes an aircraft having at least one propulsion assembly according to one of the preceding variants. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The abovementioned features of the invention, along with others, will become more clearly apparent upon reading the following description of an exemplary embodiment, the description being given with reference to the appended drawings, in which: 
         FIG. 1  is a side view of an aircraft having a propulsion assembly according to the invention, 
         FIG. 2  is an axial cross section of a propulsion assembly according to a first embodiment of the invention, 
         FIG. 3  is an axial cross section of a propulsion assembly according to a second embodiment of the invention, 
         FIG. 4  is a schematic depiction of the fire-fighting system according to a first embodiment of the invention, 
         FIG. 5  is a schematic depiction of the fire-fighting system according to a second embodiment of the invention, 
         FIG. 6  is a schematic depiction of the fire-fighting system according to a third embodiment of the invention, 
         FIG. 7  is a schematic depiction of the fire-fighting system according to a fourth embodiment of the invention, and 
         FIG. 8  is an axial cross section of a propulsion assembly of the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows an aircraft  100  that has a propulsion assembly  150  according to the invention that has a turbofan. 
     In the following description, and by convention, the X direction is the longitudinal direction of the propulsion assembly and of the turbofan, with positive orientation in the direction of forward movement of the aircraft  100 , the Y direction is the transverse direction of the propulsion assembly and of the turbofan, which is horizontal when the aircraft is on the ground, and the Z direction is the vertical direction or vertical height when the aircraft is on the ground, these three directions X, Y and Z being mutually orthogonal. 
       FIG. 2  shows a propulsion assembly  250  according to a first embodiment of the invention and  FIG. 3  shows a propulsion assembly  350  according to a second embodiment of the invention. 
     The propulsion assembly  250 ,  350  according to the invention is similar to the propulsion assembly  500  of the prior art, and elements common to the propulsion assembly  500  in  FIG. 4  and the propulsion assemblies  250  and  350  according to the invention bear the same references. 
     The propulsion assembly  250 ,  350  has a suction system  252  having an inlet  254  and an outlet  256  and mobile elements, such as the blades of a pump or of a compressor, for example, which are designed, when they move, to draw the air in via the inlet  254  and deliver the drawn-in air via the outlet  256 . 
     The propulsion assembly  250 ,  350  also has a drive means  258  that drives the movement of the mobile elements and thus causes the suction system  252  to operate, so as to cause it to draw in and deliver the air. This drive means  258  is, for example, an electric motor or a gearbox connecting, via transmission shafts, a rotor of the turbofan  102  to the mobile elements. 
     The propulsion assembly  250 ,  350  also has a transfer pipe  260  fluidically connected to the outlet  256  of the suction system  252 . 
     The propulsion assembly  250 ,  350  also has a distribution pipe  262  that is disposed in the inner compartment  140  and is fluidically connected to the transfer pipe  260 . The distribution pipe  262  has a plurality of nozzles  264  allowing the air to leave the distribution pipe  262  towards the interior of the inner compartment  140 . 
     The external annular wall  136  of the inner compartment  140  has at least one air exhaust aperture  244  that forms a connection between the inner compartment  140  and the outside and allows the air of the inner compartment  140  to be rejected towards the outside. Thus, the air that arrives via the nozzles  264  passes through the inner compartment  140  and leaves via the air exhaust aperture  244 . 
     The propulsion assembly  250 ,  350  also has a supply pipe  266 ,  366  of which one end opens into the outer compartment  112  and of which the other end is fluidically connected to the inlet  254  of the suction system  252 . 
     The propulsion assembly  250 ,  350  also has an inlet opening  268 ,  368  that passes through the external annular wall  106  of the outer compartment  112  so as to allow the outside air to be introduced into the outer compartment  112 . The inlet opening  268 ,  368  forms a connection between the outer compartment  112  and the outside. 
     Thus, when the suction system  252  is in operation, it causes a depression in the outer compartment  112  and this compels the outside air to enter the outer compartment  112  via the inlet opening  268 ,  368 . The air then enters the supply pipe  266 ,  366  so as to pass through the suction system  252  and be expelled towards the distribution pipe  262  and then the inner compartment  140  where the air leaves towards the outside via the air exhaust aperture  244 . 
     In order to regulate the air flow rate, the propulsion assembly  250 ,  350  has a regulating means that regulates the flow rate of air in the suction system  252 . 
     According to one particular embodiment, the regulating means can be passive and take, for example, the form of a valve that is mounted on the supply pipe  266 ,  366  and opens/closes according to the pressure in the supply pipe  266 ,  366 . According to another exemplary embodiment, the regulating means can be a heat pipe associated with a mechanical regulating system, of the valve type, wherein the heat pipe transports temperature information from at least one of the compartments  112 ,  140  to the mechanical regulating system. 
     According to another particular embodiment, the regulating means can be active, and it takes the form of a control unit, such as a controller, and sensors, wherein the control unit controls the drive means  258  so as to accelerate or slow the mobile elements of the suction system  252  according to the needs of the aircraft  100 , and in particular according to information, in particular temperature information, delivered by the sensors distributed in the propulsion assembly  150 ,  250 ,  350 . 
     The forced ventilation caused by the presence of the suction system  252  can thus be regulated according to the needs of the aircraft  100 . Furthermore, since the ventilation is forced, the inlet opening  268 ,  368  does not need to take the form of a scoop, and it can be only a hole that remains flush with the external annular wall  106  and generates only very limited additional drag. Furthermore, a single suction system allows both compartments to be ventilated and cooled. 
     In the case of an active regulating means, the propulsion assembly  150  can thus have, for example, at least one temperature sensor that measures the temperature of equipment to be monitored in the inner compartment  140  or the outer compartment  112  and that is connected to the control unit and, according to a predefined temperature threshold, the control unit will instruct the drive means  258  so as to accelerate or slow the suction system  252 . 
     The control unit comprises, for example, connected by a communication bus: a processor or CPU (central processing unit); a random-access memory (RAM); a read-only memory (ROM); a storage unit such as a hard disk or a storage medium reader, such as an SD (secure digital) card reader; at least one communication interface that allows the control unit to communicate, inter alia, with the suction system  252  and the sensors. The communication interface also makes it possible to communicate with the system for regulating and monitoring the engine (also known as “FADEC” in the art) that collects data relating to fire detection and triggers, if necessary, the extinguishing procedures. 
     The processor CPU is capable of executing instructions loaded into the RAM from the ROM, from an external memory (not shown), from a storage medium (such as an SD card), or from a communication network (not shown). When the controller C is powered up, the processor CPU is capable of reading instructions from the RAM and of executing them. These instructions form a computer program that causes the processor CPU to implement all or some of the algorithm and the steps described here. 
     In order to ensure better agitation of the air in the outer compartment  112 , the inlet opening  268 ,  368  and the open end of the supply pipe  266 ,  366  that opens into the outer compartment  112  are diametrically opposite one another relative to the longitudinal axis X. Thus, the air that enters via the inlet opening  268 ,  368  has to pass through half of the outer compartment  112 , for one part of the flow of air via the port side and for another part of the flow via the starboard side, so as to reach the end of the supply pipe  266 ,  366 . 
     In the embodiment in  FIG. 2 , the inlet opening  268  is in the bottom part of the propulsion assembly  250  and the open end of the supply pipe  266  is disposed in the top part of the propulsion assembly  250 . 
     The inlet opening  268  can thus also act as a drainage opening so as to evacuate the liquids that could be present in the outer compartment  112 . 
     In this embodiment, the suction system  252  is in the bottom part of the outer compartment  112  and the supply pipe  266  then passes through half of the outer compartment  112 . 
     In the embodiment in  FIG. 3 , the inlet opening  368  is in the top part of the propulsion assembly  350  and the open end of the supply pipe  366  is disposed in the bottom part of the propulsion assembly  350 . 
     In the bottom part of the propulsion assembly  350 , an additional opening  370  is then provided through the external annular wall  106  of the outer compartment  112  so as to ensure drainage of liquids that could be present in the outer compartment  112 . 
     In this embodiment, the suction system  252  is in the bottom part of the outer compartment  112  and the supply pipe  366  is relatively short. 
     In order to make the circulation of the air in the inner compartment  140  easier, the distribution pipe  262  and the nozzles  264  are at the front of the inner compartment  140  and the or each air exhaust aperture  244  is at the rear of the inner compartment  140 . 
     In the embodiment of the invention that is presented in  FIGS. 2 and 3 , the distribution pipe  262  takes the form of a ring torus coaxial with the longitudinal axis X, and the nozzles  264  are distributed along the torus and oriented towards the rear so as to eject the air towards the rear of the inner compartment  140 . 
     In the embodiment of the invention that is presented in  FIGS. 2 and 3 , the suction system  252  is arranged in the outer compartment  112 , but it could be disposed elsewhere, such as in the inner compartment  140 , for example. 
       FIGS. 4 to 7  show fire-fighting systems  600 ,  700 ,  800 ,  900  according to various embodiments. These various embodiments can be implemented in a propulsion assembly  150 ,  250 ,  350  according to the various embodiments described above. In the embodiment in  FIG. 4 , the suction system  252  is shown in the inner compartment  140 , but it could be in the outer compartment  112 . In the same way, in the embodiments in  FIGS. 5 to 7 , the suction system  252  is shown in the outer compartment  112 , but it could be in the inner compartment  140 . 
     Each of  FIGS. 4 to 7  shows the outer compartment  112  with the inlet opening  268 ,  368  that allows the outside air to be introduced and the inner compartment  140  with the air exhaust aperture  244 . Between the two compartments  112  and  140  the supply pipe  266 ,  366  and the transfer pipe  260  extend in succession on either side of the suction system  252 , and the transfer pipe  260  joins the distribution pipe  262  that opens into the inner compartment  140  via the nozzles  264 . 
     The walls of the outer compartment  112  and inner compartment  140  are passed through by the supply pipe  266 ,  366  and the transfer pipe  260  in this case via bulkhead fittings  602   a - b.    
     In each of the embodiments in  FIGS. 4 to 7 , the fire-fighting system  600 ,  700 ,  800 ,  900  has a reservoir  604  containing an extinguishing fluid, a discharge pipe  606  of which a first end is fluidically connected to the reservoir  604 , and a control system  608  interposed between the reservoir  604  and the discharge pipe  606  that alternately adopts a closed position preventing the extinguishing fluid from flowing into the discharge pipe  606  from the reservoir  604  or an open position allowing the extinguishing fluid to flow into the discharge pipe  606  from the reservoir  604 . The control system  608  is controlled for example by the control unit. 
     The control system  608  is for example a controlled valve or a discharge head that has a disc that closes the reservoir  604  and an explosive cartridge that destroys the disc when it is activated. 
     The second end of the discharge pipe  606  is arranged so as to supply the transfer pipe  260 , when the control system  608  is in the open position. 
     Thus, the extinguishing fluid is conveyed into the inner compartment  140  using the transfer pipe  260 , and this allows a saving in terms of components. 
     In the embodiment in  FIG. 4 , the second end of the discharge pipe  606  opens directly into the transfer pipe  260 , upstream of the nozzles  264 . In this case, the discharge pipe  606  passes through the inner compartment  140 , but depending on the position of the suction system  252 , the discharge pipe  606  can join the transfer pipe  260  outside the inner compartment  140 . In this embodiment, the inner compartment  140  is considered to be a potentially flammable zone, and the outer compartment  112  is not considered to be a potentially flammable zone. 
     In the embodiment in  FIG. 5 , which is a variant of the embodiment in  FIG. 4 , the fire-fighting system  700  also has a discharge sub-pipe  702  of which a first end opens into the discharge pipe  606  and of which a second end opens into the outer compartment  112 . Thus, the extinguishing fluid is distributed between the two compartments  112  and  140 . Furthermore, the extinguishing fluid that is sent towards the outer compartment  112  then reaches the inner compartment  140  via the supply pipe  266 ,  366  and the transfer pipe  260 . In this embodiment, the inner compartment  140  and the outer compartment  112  are considered to be potentially flammable zones. The second end of the discharge sub-pipe  702  opens in this case via nozzles  704 . 
     In the embodiment in  FIG. 6 , the second end of the discharge pipe  606  opens directly into the outer compartment  112 , in this case via nozzles  802 . The extinguishing fluid that is thus sent towards the outer compartment  112  then reaches the inner compartment  140  via the supply pipe  266 ,  366  and the transfer pipe  260 . In this embodiment, the inner compartment  140  and the outer compartment  112  are considered to be potentially flammable zones. 
     The embodiment in  FIG. 7  is a variant of the embodiment in  FIG. 5 , in which the control system  608  has a first control sub-system  902  and a second control sub-system  904 , wherein the first control sub-system  902  controls the flow of the extinguishing fluid into the discharge pipe  606  and wherein the second control sub-system  904  controls the flow of the extinguishing fluid into the discharge sub-pipe  702 . The first control sub-system  902  and the second control sub-system  904  can be controlled independently so as to allow the flow into the discharge pipe  606  or the discharge sub-pipe  702  or both. In this embodiment, the inner compartment  140  and the outer compartment  112  are considered to be potentially flammable zones. 
     In each of the embodiments in  FIGS. 4 to 7 , the propulsion assembly has a non-return valve  650  that is arranged on the transfer pipe  260  between the suction system  252  and the nozzles  264 , and more specifically, when the second end of the discharge pipe  606  opens directly into the transfer pipe  260 , the non-return valve  650  is arranged on the transfer pipe  260  between the second end and the nozzles  264  so as to prevent the reflux of the air and the extinguishing fluid towards the suction system  252  and the outer compartment  112 . 
     While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.