FR3039208A1 - DEFROSTING AN AIR INLET LIP AND COOLING A TURBINE HOUSING OF A PROPELLANT AIRCRAFT ASSEMBLY - Google Patents

Abstract

Propulsion unit (10 '), comprising a turbomachine surrounded by a nacelle (26) comprising an annular lip (30) of air intake equipped with a deicing circuit (38), the turbine engine comprising a turbine (20) surrounded by a casing (46) equipped with a cooling circuit (40), characterized in that said de-icing circuit and said cooling circuit are connected to each other and to a pump (46) for the circulation of a same coolant in these circuits.

Description

Defrosting an air intake lip and cooling a turbine casing of an aircraft propulsion unit

TECHNICAL AREA

The present invention relates to the deicing of an air intake lip and the cooling of a turbine casing of an aircraft propulsion unit.

STATE OF THE ART

A propulsion unit comprises a motor of the turbomachine type which is surrounded by a nacelle, this nacelle comprising an annular lip of air intake in particular in the engine.

In the case where the turbomachine is a turbofan engine, the air flow that passes into the air inlet lip passes through a fan blade and then splits into a primary air flow that enters the turbomachine and in a secondary air stream flowing around the turbomachine.

The turbomachine comprises, from upstream to downstream, in the direction of gas flow, at least one compressor, an annular combustion chamber and at least one turbine.

The role of the air intake lip on a propulsion unit is to allow the air supply of the engine over its entire operating range, while minimizing losses and drag. However, an air intake lip is in direct contact with the external environment of the propulsion unit and is subjected to external aggression, such as in particular icing. Frost formation on the air intake lip can result in particular in a reduction of its efficiency and the detachment of ice sheets which, passing through the air inlet, present a risk of damage to the engine and particular blower blading.

In order to limit the phenomena of icing on the intake air lip of a propulsion unit, an NAI system (acronym for the English nacelle

Anti Icing) deicing the lip is implemented. This is conventionally a hot air sampling system for heating the outer surface of the air intake lip.

In the present technique, de-icing air is taken from a high-pressure compressor (HP) of the turbomachine, then conveyed via a pipe to de-icing ducts extending at the lip of the engine. air inlet. From a performance point of view, this hot air defrost feature results in the need for air bleed on the HP compressor, resulting in a loss of engine air flow and therefore a loss of performance. of the motor.

The Applicant has already proposed a solution to this problem in the document FR-A1-3 001 253, which describes a system in which engine lubricating oil circulates in the air intake lip of the nacelle, in view of its de-icing.

Furthermore, a turbomachine turbine must be cooled in particular to control the radial clearances between the turbine rotor and the turbine casing that surrounds the rotor. In the current technique, this cooling is performed by air taken from the compressor low pressure (BP) and high pressure (HP), or in the secondary flow. From a performance point of view, these samples also result in a loss of air flow worked, and therefore a loss of engine performance.

Concerning the ventilation of the low pressure turbine (LP), pipelines convey air taken from the HP compressor to the LP turbine casing. This air serves to ventilate the first turbine distributor stage as well as the fasteners of the different stages of the LP turbine rotor.

For controlling the games of the high pressure turbine casing (HP), there is provided air bleed pipes from the HP compressor and going to the HP turbine housing. A control valve is used to mix air flows and regulate flow.

Finally, for the control of LP turbine casings, the motor is equipped with a system conveying air taken either in cold source (secondary vein) or hot source (HP compressor) to a shower collar system located around the LP turbine casing. A control valve controls the air flow.

In the current technique, the cooling means of the turbomachine turbine of a propulsion unit are therefore relatively complex and totally independent of the deicing means of the air intake lip of this propulsion unit.

The present invention provides an improvement to this technology.

DESCRIPTION OF THE INVENTION The invention proposes for this purpose a propulsion unit, comprising a turbomachine surrounded by a nacelle comprising an annular air inlet lip equipped with a de-icing circuit, the turbine engine comprising a turbine surrounded by a casing. equipped with a cooling circuit, characterized in that said de-icing circuit and said cooling circuit are connected to each other and to a pump for the circulation of a same coolant in these circuits. The invention thus proposes to de-ice the air inlet lip by means of a coolant and to cool the turbine casing with the same heat transfer fluid. The coolant circulates in the defrost circuit to warm the lip. It then cools before being injected into the cooling circuit of the turbine housing where it will absorb calories and heat up before being used again to warm the air intake lip. The circulation of the heat transfer fluid at the turbine casing makes it possible to cool the latter. The cooling of the turbine casing includes turbine ventilation and / or game control in the turbine.

This in particular makes it possible to reduce the pressure drop associated with the extraction of air on the engine required in the prior art to provide deicing and cooling functions. The advantage of using a heat transfer fluid with heating value higher than that of air is to allow improved heat exchange. The coolant is indeed chosen to have heat exchange characteristics greater than those of air.

The proposed solution makes it possible to make progress in the pooling of functions and thus in the reduction of equipment needed by the systems. These techniques make it possible, while preserving the functional level required for a propulsion system, to reduce the weight of the external configuration and to improve engine performance.

Furthermore, the invention solves secondary problems directly affecting the performance of the propulsion system. This is for example: - the improvement of the aerodynamic lines of the nacelle, because it may have less scoop air sampling on the external flow to supply the cooling heat exchangers of the turbomachine, - the reduction of the mass of the external configuration of the engine: it is indeed possible to reduce or even eliminate some systems through the coupling of functions, and - the reduction of the amount of heat exchange between fluids, so losses. The propulsion unit according to the invention may comprise one or more of the following characteristics, taken separately from each other or in combination with each other: said deicing circuit comprises at least one deicing duct extending into said lip of air inlet, the lip comprises two superimposed skins and defining between them said at least one deicing pipe, one of the skins defines an external surface of the lip, the skins define between them a single defrosting pipe of relatively small thickness and which is configured to ensure the circulation of a coolant film, - the skins define between them several independent defrosting lines, which are configured to each ensure the circulation of heat transfer fluid, - one of the skins comprises hollow parts which are closed by the other skins to define said canalisa defrosting operations, - the lip is fixed to the rest of the nacelle by removable fixing means, for example of the screw-nut type, - said at least one de-icing pipe has a generally annular shape and is sectorized, each pipe sector preferably being connected to an inlet and a heat transfer fluid outlet which are independent of the coolant inlet and outlet of the other pipe sectors. - The fluid inlets of the pipe sectors are connected to the pump by valves, - said cooling circuit comprises at least one cooling pipe extending around said housing, and preferably a plurality of cooling pipes arranged next to the others, - said at least one cooling pipe has a generally annular shape and is sectorized, each pipe sector preferably being connected to an inlet and a heat transfer fluid outlet which are independent of the heat transfer fluid inlet and outlet of the other sectors said pipe sectors are connected to each other by distributing collectors, - said pump is mounted in said nacelle, and - said pump is powered by an electric generator or comprises a rotor driven by an output shaft of a gearbox also mounted in the nacelle.

DESCRIPTION OF THE FIGURES The invention will be better understood and other details, characteristics. and advantages of the invention will appear more clearly on reading the following description given by way of nonlimiting example and with reference to the accompanying drawings in which: - Figure 1 is a schematic axial sectional view of a propulsion assembly, FIG. 2 is a diagrammatic view in axial section of a propulsion assembly according to the invention; FIG. 3 is a diagrammatic perspective view of a deicing circuit of an air intake lip of a propulsion assembly according to the invention, - Figure 4 is a schematic perspective view of a cooling circuit of a turbine casing of a propulsion assembly according to the invention, - Figures 5a, 5b and 5c are half schematic views in axial section of an air inlet lip of a propulsion assembly according to alternative embodiments of the invention, - Figure 6 is a schematic front view and in cross section of a lip of entrance r of a propulsion assembly according to the invention, - Figure 7 is another partial schematic view of a heat transfer fluid circuit for a propulsion assembly according to the invention, and - Figure 8 is a schematic view of a pipe cooling a turbine casing of a propulsion unit according to the invention.

DETAILED DESCRIPTION

A propulsion unit 10 comprises a motor or a turbomachine which is surrounded by a nacelle.

With reference to FIG. 1, the turbomachine is a turbofan engine which comprises, from upstream to downstream in the direction of flow of the gases, a low pressure compressor (LP) 12, a high pressure compressor (HP 14, an annular combustion chamber 16, a high pressure turbine (HP) 18 and a low pressure turbine (BP) 20, which define a flow vein of a primary gas flow 22.

The rotor of the high pressure turbine 18 is secured to the rotor of the high pressure compressor 14 so as to form a high pressure body, while the rotor of the low pressure turbine 20 is secured to the rotor of the low pressure compressor 12 so as to form a low pressure body. The rotor of each turbine rotates the rotor of the associated compressor about an axis 24 under the effect of the thrust of the gases from the combustion chamber 16.

In the description which follows, the terms upstream and downstream refer to the flow of gases in the turbomachine along the axis 24, and the terms upstream, downstream, radial, etc., must be considered as defined by with respect to this axis 24 or referring to this axis 24.

The nacelle 26 extends around the turbomachine and defines around it an annular flow vein of a secondary flow 28. The upstream end of the nacelle 26 defines an annular lip 30 of air inlet in which enters a flow of air through a fan 32 of the turbomachine, then divide and form the primary flow 22 and secondary 28 above.

In the prior art illustrated in FIG. 1, the air inlet lip 30 is defrosted by means of a circuit (schematically represented by dashed lines 34) of defrosting by the circulation of compressed air taken from the engine or from Engine lubrication oil, in the air inlet lip.

Furthermore, still in the prior art, the LP turbine 20 is cooled by means of a circuit (schematically represented by dashed lines 36) for cooling by circulating compressed air taken from the engine, around the LP turbine casing.

The present invention provides an advantageous improvement to this technology, the general principle of which is diagrammatically illustrated in FIG.

Although the turbomachine shown in FIG. 2 is a double-flow, double-body turbojet, this FIG. 2 represents a particular example of application of the invention that can naturally be applied to other types of turbomachine. The propulsion unit 10 'of FIG. 2 comprises a circuit 38 for deicing the air inlet lip 30 and a circuit 40 for cooling the turbine, and in particular the low-pressure turbine 20.

The defrosting circuit 38 comprises at least one de-icing line 42 extending into the lip 30. The cooling circuit 40 comprises at least one cooling duct 44 extending around the casing 46 of the LP turbine. The circuits 38, 40 are connected to each other and to a pump 48 which ensures the circulation of a coolant, such as a coolant, in the circuits.

In the example shown, the deicing circuit 38 comprises a fluid inlet connected to the pump 48 and a fluid outlet also connected to the pump. The cooling circuit 40 comprises a fluid inlet connected to the pump 48 and a fluid outlet also connected to the pump. The pump 48 is thus a four-way pump. As a variant, it could be a two-way pump connected, for example, respectively to the fluid inlet of the circuit 38 and to the fluid outlet of the circuit 40, the fluid outlet of the circuit 38 then being directly connected to the inlet of the circuit. fluid circuit 40. The system can therefore operate independently, in "circuit" closed. Although not shown, this system could include a coolant reservoir.

The pump 48 is here mounted in an enclosure of the nacelle 26. It can be mounted on the gearbox 50 of the AGB (acronym for Accessory Gear Box) type located in this enclosure. The rotor of the pump is then directly driven by an output shaft of the box 50. In a variant, the pump could be powered by an electric generator, which could itself be mounted on the box 50.

The pipes 52, 52 'connecting the pump 48 to the deicing circuit 38 can be housed in the nacelle 26. The lines 54, 54' connecting the pump 48 to the cooling circuit 40 extend partly into the nacelle 26 and around the motor, in an annular space extending between the casings of the motor and an annular envelope surrounding the motor and defining internally the flow vein of the secondary flow 28. The lines 54, 54 'must therefore pass through this vein. For this, they can pass in substantially radial arms 56 of servitudes passage of an intermediate casing of the turbomachine 10 '. This intermediate casing is located between the compressors BP 12 and HP 14 of the turbomachine.

FIG. 3 very schematically represents the de-icing circuit 38 of the air inlet lip 30. This circuit 38 comprises one or more annular ducts 42 which extend in the lip 30 about the axis 24 of the turbine engine. In the case where this circuit comprises several pipes 42, they could be connected by one of their circumferential ends to a distributor 58 connected to a path of the pump 48, and at the other of their ends to a manifold 60 connected to another pump path, by the pipes 52, 52 'above.

FIG. 5a shows a first embodiment of the air inlet lip 30. The air intake lip 30 comprises two skins 64, 66 superimposed and spaced apart from one another so as to delimit between they a single deicing duct 42 which extends over substantially the entire range of the skins. The deicing duct 42 is thus configured to ensure the circulation of a relatively thin film of coolant between the skins 64, 66.

A first skin or outer skin 64 defines the outer surface of the air inlet lip 30. In the example shown, it has a substantially C-shaped section whose circumferential edges downstream, radially inner and outer, are connected respectively to the upstream circumferential edges of walls of the nacelle 26. The second skin or inner skin 66 also has a substantially C-shaped section. The aforementioned edges of the walls of the nacelle 26 are interconnected by a transverse annular wall 68 which may be designed to hermetically seal the line 42 at the inner and outer peripheries of the skins 64, 66.

In the embodiment of FIG. 5a, the fluid can directly heat the entirety of the outer skin 64 with a view to deicing the lip 30.

Figure 5b shows an alternative embodiment of the air intake lip 30 which also comprises two skins 64, 66 'superimposed.

The outer skin 64 is similar to that of Figure 5a. The inner skin 66 'is here shaped to define, on the side of the outer skin 64, recesses which are closed by the outer skin 64 and which are intended to form independent deicing lines 42.

These recesses preferably have an annular shape so that the deicing ducts 42 are annular. The lip 30 comprises a plurality of de-icing lines, here six in number, which are configured to ensure the circulation of heat transfer fluid between the skins 64, 66 '.

The skins 64, 66, 66 'of Figures 5a and 5b may be made of sheet metal, the skin 66' being obtainable by stamping a sheet. The outer skin 64 may be of the shielded type, for example by adapting the material of this skin or by increasing its mass density. In general, it will be sought that the outer skin 64 resists as much as possible to the impacts that may occur by collision with foreign objects such as for example birds or hail, a compromise being sought between the resistance of the outer skin and its mass. It can also be sought that the outer skin 64 is deformed as much as possible without cracking in the event of impact, in order to avoid or limit the leakage of heat transfer fluid that would result from the impact.

In the embodiment of Figure 5b, the fluid directly heats parts of the outer skin 64, namely the parts that close the recesses of the inner skin 66, the rest of the outer skin being heated by conduction.

The variant of embodiment of FIG. 5c differs from that of FIG. 5a in that the lip 30 is removable, that is to say that it is removably or removably attached to the walls of the nacelle 26. this, the lip 30 may comprise at each of its circumferential edges an annular clamping flange by means 70 of the screw-nut type for example on the nacelle 26 and for example on the transverse wall 68 of the nacelle.

In case of damage to the lip 30, for example because of the impact of a foreign body such as a bird, it can easily be disassembled and replaced by a new one. The deicing duct 42 is then replaced since it is integrated with the lip 30.

Referring now to FIG. 6, which represents an exemplary embodiment of the means for supplying heat transfer fluid and discharging this fluid from the or each de-icing pipe 42.

In the example shown, a single de-icing pipe 42 is shown, this pipe having a generally annular shape and being sectored or compartmentalized. The pipe 42 is thus formed of several sectors, here four in number, which are arranged circumferentially end to end around the axis of revolution of the pipe. The pipe sectors here have the same circumferential extent which represents substantially an angle of about 90 °.

The pipe sectors are separated from each other by substantially radial walls 72, which are four in number in the example shown and regularly distributed around the aforementioned axis. These walls 72 are located respectively at 3h (hours), 6h, 9h and 12h by analogy with the dial of a clock.

The heat transfer fluid supply means form a pipe portion 52 and the means for discharging this fluid form a pipe portion 52 'which returns towards the pump 48. Each pipe sector comprises a fluid inlet 74 and an outlet fluid inlet 76. The fluid inlet 74 of each pipe sector is located in an upper portion of the sector, and its fluid outlet 76 is located in a lower portion so that the fluid can flow from the input to the output by gravity in case of failure or stoppage of the pump 50. The fluid inlets and outlets are here located at the circumferential ends of the pipe sectors.

The fluid outlets 76 of the two segments of pipe located in the lower part are pooled and include a manifold 78 located substantially at 6 o'clock.

As schematically shown in FIG. 7, a valve 80 can be associated with each fluid inlet 74 so that the supplies of the pipe sectors can be controlled independently of one another. Advantageously, these valves 80 are bypass valves that can be controlled to divert the heat transfer fluid directly from the inlet pipe 52 to the pipe 52 'discharging towards the pump, without passing through the pipe sectors (but by means of bypass lines 82).

In the event of impact of a foreign body on the lip, and damage of the lip to the point of causing a heat transfer fluid leak in a pipe sector, this system can make it possible to keep at least one undamaged part of the pipeline sectors. In the case of a partial or total cut of the fluid circuit and / or if there is a circuit failure, the valves 80 can create a deflection which redirects the fluid to the manifold 78 or the discharge pipe 52 ' , without passing through the damaged area (s). The circuit failure can be detected by means of pressure sensors associated with the valves 80.

The heat transfer fluid is preferably non-flammable so that any leakage of heat transfer fluid does not cause a fire start if fluid sucked into the air inlet reaches a high temperature zone of the engine. This limits the risk of engine fire in case of impact of a foreign body on the lip.

Figure 4 very schematically shows the cooling circuit 40 of the turbine casing. This circuit 40 comprises one or more annular ducts 44 which extend around the axis 24 and the casing 46. In the case where this circuit comprises several ducts 44, they could be connected by one of their circumferential ends to a distributor 84 connected to a path of the pump 48, and at the other of their ends to a manifold 86 connected to another path of the pump, by the pipes 54, 54 'above.

FIG. 8 represents a particular embodiment of the cooling circuit 40.

This cooling circuit 40 here comprises an annular row of members 88 compartmentalized and each having a collector compartment 90 and a distribution compartment 92. The members 88 are therefore distributing collectors. The bodies 88 are here four in number and are regularly distributed around the axis 24. The pipes 44 are four in number and are sectored, the sectors of each pipe being connected to each other by the organs 88. Each sector the channel 44 extends between two adjacent members 88 and includes a circumferential end connected to the collection compartment 90 of a member 88 and an opposite circumferential end connected to the distribution compartment 92 of an adjacent member 88.

The heated heat transfer fluid is driven by the pump 48 to circulate in the pipes 42 of the deicing circuit 38 of the lip 30. After circulation in the pipes 42 and deicing the lip 30, the fluid is cooled and is driven by the pump to supply the distribution compartments 90 of the organs 88. The heat transfer fluid flows in the channel sectors 44, around the housing 46, to cool it. The fluid is then recovered by the collecting compartments 92 of the organs 88 and returned to the pump.

Claims (10)

1. Propulsion unit (10 '), comprising a turbomachine surrounded by a nacelle (26) having an annular lip (30) of air inlet equipped with a defrosting circuit (38), the turbine engine comprising a turbine (20). ) surrounded by a casing (46) equipped with a cooling circuit (40), characterized in that said de-icing circuit and said cooling circuit are connected to each other and to a pump (48) for the circulation of the same heat transfer fluid in these circuits. The propulsion assembly (10 ') of claim 1 wherein said defrost circuit (38) comprises at least one defrost line (42) extending into said air inlet lip (30). 3. Propulsion unit (10 ') according to claim 2, wherein the lip (30) comprises two skins (64, 66) superimposed and defining between them said at least one deicing pipe (42). The propulsion assembly (10 ') according to claim 3, wherein one (64) of the skins defines an outer surface of the lip (30). 5. Propulsion unit (10 ') according to one of claims 2 to 4, wherein said at least one deicing pipe (42) has a generally annular shape and is sectored, each pipe sector being preferably connected to an inlet (74) and an outlet (76) of heat transfer fluid which are independent of the heat transfer fluid inlets and outlets of the other pipe sectors. The propulsion assembly (10 ') according to claim 5, wherein the fluid inlets (74) of the pipe sectors are connected to the pump (48) by valves (80). 7. Propulsion unit (10 ') according to one of the preceding claims, wherein said cooling circuit (40) comprises at least one cooling pipe (44) extending around said housing (46), and preferably several pipes cooling arranged next to each other. 8. Propulsion unit (10 ') according to the preceding claim, wherein said at least one cooling pipe (44) has a generally annular shape and is sectorized, each pipe sector being preferably connected to an inlet and an outlet of heat transfer fluid which are independent of the heat transfer fluid inlet and outlet of the other pipe sectors. 9. Propulsion unit (10 ') according to the preceding claim, wherein said duct sectors (44) are connected to each other by distributing manifolds (88). 10. Propulsion unit (10 ') according to one of the preceding claims, wherein said pump (48) is mounted in said nacelle (26) and is powered by an electric generator or comprises a rotor driven by an output shaft of a gearbox (50) also mounted in the nacelle.