WEDGE FOR OPENWORK POLE FOOT

Abstract

The main object of the invention is a wedge (100) for a blade root (58) of a propeller blade (48) of a turbomachine (1) propeller (32), characterized in that it is openworked to allow the flow of a ventilation airflow to the blade root (58).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of turboengines, especially that of open propellers for a turboengine, and more specifically to cooling of elements of these propellers, blade feet in particular. In relates accordingly to a cleat for a blade foot, a propeller for a turboengine comprising such a cleat, and also the turboengine comprising such a propeller.

[0002] The invention applies to any type of terrestrial or aeronautical turboengines, and especially to aircraft turboengines such as turbojets and turboprops. More particularly, the invention applies preferably in the field of turboengines for aircraft whereof the receiver comprises a pair of open contrarotating propellers, this type of turboengine also being called <<open fan>>, or having the English terms <<open rotor>> or <<propfan>>. Such a turboengine can comprise for example a fan fixed directly on the power turbine and outside the nacelle, or driven by means of a reducer power turbine.PRIOR ART

[0003] FIG. 1schematically illustrates a turboengine 1with a pair of open contrarotating propellers, so-called <<open rotor>>, according to a classic realisation of the prior art, as is known from patent application FR 2 941494.

[0004] In this FIG. 1, the direction A corresponds to the longitudinal direction or axial direction, parallel to the longitudinal axis 2of the turboengine 1. The direction B corresponds as such to the radial direction of the turboengine 1. Also, arrow 4shows the main direction of gas flow through the turboengine 1. The terms <<upstream>> and <<downstream>> utilised throughout the description are to be considered relative to this gas discharge direction 4.

[0005] In its front part, the turboengine 1has an air intake 6continuing to the rear via a nacelle 8, the latter comprising overall an outer skin 10and an inner skin 12, both centred on the axis 2and offset radially to each other.

[0006] The inner skin 12forms an external radial housing for a gas generator 14, conventionally comprising, from front to back, a low-pressure compressor 16, a high-pressure compressor 18, a combustion chamber 20, a high-pressure turbine 22, and an intermediate-pressure turbine 24. The compressor 16and the turbine 24are connected mechanically by a shaft 26to form a low-pressure body, while the compressor 18and the turbine 22are connected mechanically by a shaft 28to form a higher-pressure body. Consequently, the gas generator 14preferably has a classic design, a so-called double body.

[0007] Downstream of the intermediate-pressure turbine 24is a receiver 30with a pair of open contrarotating propellers, driven in this example by free power turbines. As a variant, a reducer power turbine can be used. More precisely, this receiver 30is placed downstream of a fixed housing 42, itself arranged in the rear extension of the external radial housing 12of the gas generator 14. Also, the housings 12and 42can be made in a single piece. The fixed housing 42then extends to the rear as it narrows according to the radial direction to form a fixed shaft 57centred on the axis 2, forming the fixed housing of the receiver 30.

[0008] The receiver 30first comprises a first rotating assembly 32 afitted with a first propeller 32, a first free power turbine 34driving this propeller, and a first rotating structural device 33located in the axial extension of the free turbine 34to the front, by being interposed between the first stage of this turbine and the fixed housing 42. The structural rotating device 33generally has the form of a plurality of arms spaced circumferentially to each other, and which extend radially. These arms are connected to the first propeller 32by bearing the external turbine housing 49, in turn connected to the propeller 32in particular by a flange or a plurality of clips 44to radially deflect this propeller 32to the exterior. The clips 44have an internal radial end attached to the external housing 49, and an external radial end attached to a polygonal ring (not shown in FIG. 1) for support of blades 48. These blades 48project radially to the exterior from a housing or external propeller cowling 46, whereof one of the particular features is being in the rear aerodynamic continuity of the outer skin 10of the nacelle.

[0009] Similarly, the receiver 30comprises a second rotating assembly 36 afitted with a second propeller 36, a second free power turbine 38driving this propeller, and a second structural rotating device 37located in the axial extension of the free turbine 38to the rear, being located behind the last stage of this turbine 38. The rotating structural device 37, which extends essentially radially, supports the second propeller 36by being connected thereto in particular by a flange or a plurality of clips 51for radially deflecting the propeller 36to the exterior. Here also, the clips 51have an internal radial end attached to the rotating structural housing 37, and an external radial end attached to a polygonal ring (not shown in FIG. 1) to support the blades 55. These blades 55project radially towards the exterior from an external housing or cowling 54, which is in the rear aerodynamic continuity of the external cowling 46of the first propeller 32.

[0010] Also, the first and second free turbines 34, 38are nested in each other to form a pair of contrarotatory turbines. The stages of the first turbine 34are arranged to alternate with the stages of the second turbine 38, in direction A. This doublet therefore can also be assimilated into a turbine with two contrarotatory rotors. By way of indication, the free turbines 34, 38have no direct mechanical link with the rotating component of the gas generator 14, specifically they do not drive nor are driven by the elements 16, 18, 22, 24. Only the gas of the primary seam escaping from the intermediate-pressure turbine 24therefore ensures rotation of these free turbines 34, 38forming the doublet of contrarotatory turbines.

[0011] In reference now more specifically to FIGS. 2 to 4, the design of the first propeller 32is shown in greater detail, given that the second propeller 36has an identical or similar design, and that accordingly it will not be described further.

[0012] As mentioned earlier, the propeller 32comprises a polygonal ring 47serving as support for the blades 48, this ring 47forming a hub of the propeller. It comprises a plurality of housings 50spaced circumferentially to each other, these housings 50being called radial housings. Each of them receives a pivot 52, a roller 80being interposed between this pivot 52and its associated housing 50forming a bore, as shown in FIG. 3.

[0013] Each pivot 52has a lower part 52 aplaced inside its associated housing, this lower part 52 abeing substantially cylindrical and hollow so as to present a cross-section in a general U-shape open radially towards the interior. Also, the pivot 52extends radially towards the exterior via an upper part 52 blocated above the ring 47, this upper part 52 bhaving a groove 56shown in FIG. 4, and the function of which is to hold the foot 58of the associated blade 48. So, the pivot 52bears the blade 48and enables it to be adjusted by controlling the rotation of this same pivot 52within its housing 50of the polygonal ring 47.

[0014] The propeller 32also includes the external cowling 46illustrated only in FIGS. 1 and 3. The external surface of this cowling is contacted by external air. In this respect, it is indicated that each blade 48is equipped with a platform 59from which its aerodynamic part 60projects radially towards the exterior. Each platform 59, circular in form, is placed within an orifice provided through the cowling 46to obtain substantially projecting aerodynamic junctions.

[0015] As is more evident from FIG. 3, it is provided a blade cavity 64associated with the blade 48, the aim of this cavity being to isolate the blade foot from the rest of the turboengine 1, in particular of the primary seam passing radially towards the interior. The cavity 64has been identified schematically in FIG. 3by the dotted line referenced 64. It is effectively closed radially towards the exterior by the platform 59and the external cowling 46forming aerodynamic fairing, but also closed towards upstream by one or more caches 66, closed towards downstream by one or more caches 68, and closed radially towards the exterior by one or more caches 70, here a single cache 70fixed to the flange or the abovementioned clips 44.

[0016] It is noted that a cavity of a blade foot can be provided for each blade, as shown in FIG. 5with an internal cache 70provided for each blade, making the cavities independent of each other. Alternatively, a single cavity of blade feet can be shared by all the blades 48of the propeller 32, the single retained internal cache 70then taking the form of a crown.

[0017] As a possibility for ventilation, each cavity 64can for example be supplied with external air via a bailer 72or similar (for example a simple orifice), placed on the external cowling 46. This bailer can especially be placed downstream, and the air transiting via the cavity 64can for example then be extracted via an outlet (not shown) located further upstream. As it exits via the cavity 64, the fresh external air contacts and cools by ventilation the elements located in this cavity 64, in particular the foot 58of the blade, as has been shown by arrow 53.

[0018] Ventilation and cooling of the elements of the propeller 32, and in particular the blade feet 58, are difficult to execute, especially due to the pressure conditions with a low Mach number. However, such ventilation and such cooling are particularly important to carry out when the blades 48are made of composite materials, as they have reduced performance in high temperatures in comparison to metallic materials. Now, in the configuration shown in FIG. 1, so-called <<pusher>>, in which the open propellers are located to the rear downstream of the combustion chamber, these propellers are arranged just above the primary seam where hot gas can reach 500[deg.] C. It is therefore essential to provide specific ventilation to avoid overheating the blade feet of these open propellers.

[0019] Nevertheless, the proposed solution described hereinabove uses only the difference in pressure between the dynamic air intake downstream formed by the bailer 72, and the static air outlet upstream. It is therefore very dependent on the speed of the plane, which proves harmful during some phases such as deceleration and takeoff, where the airflow contacting the foot of the blade can prove inadequate for satisfactory cooling.

[0020] Also, this solution known from the prior art has the disadvantage of carrying out cooling and ventilation of the blade feet 58only via the exterior of the pivots 52. In other words, the blade feet 58are not cooled on direct contact of the ventilation airflow but only by conduction and / or convection mechanisms due to contact with pieces which are cooled by the ventilation flow. Because of this, cooling of the blade feet 58is not optimal.EXPLANATION OF THE INVENTION

[0021] The aim of the invention is to at least partially remedy the needs mentioned hereinabove and the disadvantages relative to the realisations of the prior art.

[0022] The particular aim of the invention is to propose a solution to enable efficacious ventilation and cooling of blade feet, in particular made of composite materials.

[0023] The object of the invention, according to one of its aspects, is a cleat for a blade foot of a turboengine propeller blade, characterised in that it is open-work to allow discharge of ventilation airflow of the blade foot.

[0024] The airflow is in particular external airflow, especially cold external airflow to allow ventilation.

[0025] The fact of having an open-work cleat can allow passage of the airflow for ventilating, and especially for cooling, the blade foot.

[0026] Due to the invention, it can be possible to ventilate and cool the blade feet by allowing circulation of the ventilation airflow directly in contact with the blade feet. The blade foot cleat, whereof the initial function is to support the blade, can be used to allow the formation of one or more passes of the ventilation airflow.

[0027] The cleat according to the invention can also comprise one or more of the following characteristics taken singly or as per all possible technical combinations.

[0028] The cleat can comprise at least one discharge channel of the airflow intended to be located under the blade foot.

[0029] Said at least one discharge channel of the airflow can comprise an axial discharge channel and / or a lateral discharge channel.

[0030] The choice and number of discharge channels for ventilation of the blade feet can be determined as a function of the preferred mechanical performance for the cleat and / or the blade.

[0031] The cleat can be open-work in a terminating manner or not. <<Terminating>> means that the openings of the cleat terminate on at least one edge of the cleat. In particular, at least one discharge channel, for example axial or lateral, or even all the discharge channels, can be terminating. As a variant, at least one discharge channel, for example axial or lateral, or even all the discharge channels, is not terminating.

[0032] The design of the blade foot cleat must especially ensure that the blade is pressed in its air cell when stopped, but also support the substantial forces generated by dynamic ingestions and stresses, limited over time but severe.

[0033] Yet another aim of the invention, according to another of its aspects, is a propeller for turboengine comprising a plurality of blades as well as a blade support ring provided with housings, each taking up a pivot bearing the foot of one of said blades,

[0000] characterised in that it comprises a cleat such as defined previously, placed between at least one of the pivots and the corresponding blade foot.

[0034] The propeller can in particular be an open propeller.

[0035] At least one of the pivots can be equipped with at least one counterweight system provided with at least one inner discharge channel of the airflow intended to come into contact with the cleat. The inner discharge channel of the airflow can cool the blade foot borne by the pivot. It can also enable cooling of any other element requiring specific ventilation. Similarly, it can also enable ejection of hot airflow to the exterior of the zone to be ventilated.

[0036] The inner channel formed in the counterweight system can capture and guide the airflow to the precise site where ventilation is required, that is, especially at the level of the blade feet.

[0037] The inner channel can have an inner end which terminates on the pivot and one at least of an introduction end and an ejection end of the airflow. In particular, the inner channel can comprise an introduction end of the airflow and an inner end terminating on the pivot to cool the pivot. As a variant, the inner channel can comprise an inner end terminating on the pivot, via which hot air from the pivot enters towards the inner channel, and an ejection end for evacuating hot air.

[0038] The introduction end and / or the ejection end can comprise introduction and / or ejection means in the form of an orifice or a bailer. The introduction end and / or the ejection end can preferably comprise a dynamic bailer for introduction and / or ejection of the airflow.

[0039] The pivot can comprise at least one inner communicating channel whereof one end terminates at the level of the blade foot and the other end terminates at the level of an inner channel of the counterweight system. The inner communicating channel can introduce the airflow from the inner end of the inner channel towards the blade foot, or eject the airflow from the blade foot towards the inner end of the inner channel. As a variant, the pivot can be provided with an inner communicating channel. The groove of the pivot for affixing the blade foot can for example be fitted with at least one orifice opposite an inner end of an inner channel of a counterweight system.

[0040] The pivot can also comprise at least one channel, for example lateral or axial, especially formed under the blade foot, to allow ventilation of the blade foot. Said at least one channel can or cannot be formed opposite a discharge channel of the cleat.

[0041] The counterweight system can comprise a counterweight arm and a counterweight. The inner channel can be located in the counterweight arm and / or the counterweight. Preferably, the counterweight arm can comprise the inner channel.

[0042] The pivot can be equipped with at least one first counterweight system, provided with at least one first inner channel fitted with an introduction end of the airflow and an inner end, and a second counterweight system, provided with at least one second inner channel fitted with an ejection end of the airflow and an inner end. The pivot can comprise a first inner communicating channel, whereof one end terminates at the level of the blade foot and the other end terminates at the level of the inner end of the first inner channel, and a second inner communicating channel, whereof one end terminates at the level of the blade foot and the other end terminates at the level of the inner end of the second inner channel.

[0043] The blades, in particular the blade feet, and / or said at least one counterweight system and / or the cleat and / or said at least one of the pivots can be made of composite material.

[0044] The counterweight arm can be made in at least two parts, especially metallic. The inner channel can especially be formed partially, especially by machining, in each of these two parts.

[0045] As a variant, the counterweight arm can be made in one part. The counterweight arm, especially made of composite material, for example woven or laminated, can integrate the inner channel, in particular from manufacture onwards.

[0046] Yet another aim of the invention, according to another of its aspects, is a turboengine, characterised in that it comprises a cleat such as defined previously or a propeller such as defined previously.

[0047] The propeller can for example be positioned upstream or downstream of a combustion chamber of the turboengine.

[0048] The turboengine can preferably be of <<open rotor>> type. In particular, the turboengine can comprise a pair of open contrarotating propellers, each of the two propellers being a propeller such as defined previously.BRIEF DESCRIPTION OF DRAWINGS

[0049] The invention will be better understood from the following detailed description of a non-limiting embodiment of the latter, and from reference to the figures, schematic and partial, of the attached drawing, in which:

[0050] FIG. 1illustrates a schematic view in longitudinal half section of a turboengine for aircraft comprising a receiver with a pair of contrarotatory propellers, according to a classic design of the prior art,

[0051] FIG. 2illustrates a partial view in perspective of one of the contrarotatory propellers of the turboengine shown in FIG. 1,

[0052] FIG. 3illustrates a partial view in section showing in more detail the ring of support des blades of the propeller, and the surrounding elements,

[0053] FIG. 4illustrates an exploded view in perspective of a blade and of its associated pivot,

[0054] FIG. 5illustrates a perspective view of a propeller of the prior art, equipped with several cavities of blade feet,

[0055] FIG. 6illustrates in perspective an example of a cleat according to the invention, and

[0056] FIG. 7illustrates, in section and partially, an example of a pivot comprising counterweight systems.

[0057] In all these figures, identical reference numerals can designate identical or similar elements.

[0058] Also, the different parts illustrated in the figures are not necessarily according to a uniform scale, to make the figures more legible.DETAILED EXPLANATION OF A PARTICULAR EMBODIMENT

[0059] An embodiment of the invention relating to an aircraft turboengine with a pair of open contrarotating propellers will now be described hereinbelow, in reference to FIGS. 6 and 7, this example not being limiting, however.

[0060] FIGS. 6 and 7are schematic and partial, and reference should be made to FIGS. 1 to 5previously described to view those elements not shown in FIGS. 6 and 7.

[0061] In reference to FIG. 6, this shows a cleat 100according to the invention.

[0062] The cleat 100is intended to be placed between the pivot 52and the blade foot 58to make discharge of airflow easier for cooling of the blade foot 58. The cleat 100is in particular housed in the base of the blade housing, at the level of the groove 56.

[0063] For this purpose, the cleat 100is open-work and comprises discharge channels 101, 102of the airflow used as conduits for cooling air.

[0064] More particularly, in this example, the cleat 100comprises an axial discharge channel 101for airflow and two lateral discharge channels 102for airflow. However, this example is not limiting and the cleat 100could comprise other types of discharge channels, their choice and their number depending especially of the mechanical performance of the cleat 100and of the blade 48.

[0065] The cleat 100can for example be advantageously placed on a pivot 52, such as described in reference to FIG. 4, the cleat 100then being located between the pivot 52and the blade foot 58(not shown).

[0066] FIG. 7illustrates a pivot 52fitted with a groove 56for affixing the blade foot 58.

[0067] The pivot 52is equipped with a first counterweight system 90and a second counterweight system 91. Each of the counterweight systems 90and 91is provided with an inner airflow channel 93and discharge channel 96.

[0068] The first counterweight system 90comprises a counterweight arm 90 aand a counterweight 90 bat the end of the arm 90 aopposite the pivot 52. Similarly, the second counterweight system 91comprises a counterweight arm 91 aand a counterweight 91 bat the end of the arm 91 aopposite the pivot 52. The counterweight arm 90 aand 91 acomprise respectively the inner channels 93and 96.

[0069] The inner channel 93has an inner end 97 awhich terminates on the pivot 52and an introduction end 97 bof the airflow.

[0070] Also, the inner channel 96has an inner end 98 awhich terminates on the pivot 52and an ejection end 98 bof the airflow.

[0071] The introduction end 97 band the ejection end 98 beach comprise a detachable dynamic bailer for passage of the airflow.

[0072] In addition, the pivot 52comprises a first inner communicating channel 99 awhereof one end terminates at the level of the blade foot 58and the other end terminates at the level of the inner channel 93of the first counterweight system 90. Similarly, the pivot 52comprises a second inner communicating channel 99 bwhereof one end terminates at the level of the blade foot 58and the other end terminates at the level of the inner channel 96of the second counterweight system 91.

[0073] In this way, the airflow is capable of being captured by the bailer dynamic at the level of the introduction end 97 bof the first counterweight arm 90 aaccording to the arrow F 1, then being discharged inside the inner channel 93and of the inner communicating channel 99 ato cool the blade foot 58according to arrow F 2. At this level, the discharge channels 101and 102of the airflow of the cleat 100permit passage of fresh air over almost the entire blade foot 58to cool the latter. Then, the resulting hot flow can be discharged in the inner communicating channel 99 band in the inner channel 96to be ejected at the level of the ejection end 98 bof the second counterweight arm 91 baccording to arrow F 3, towards the exterior or towards the nacelle of the engine.

[0074] Producing the channels 101and 102of the cleat 100to make circulation of the airflow easier can produce optimal cooling of the blade foot 58since fresh airflow comes into direct contact with the latter.

[0075] In the above, the blades 48and / or the counterweight systems 90and 91and / or the cleat 100and / or the pivot 52can be made of composite material.

[0076] Of course, the invention is not limited to the embodiment which has just been described. Various modifications can be made to it by the expert.

[0077] The expression <<comprising a>> must be understood as being synonymous with <<comprising at least one>>, unless specified otherwise.

Claims

1 1. A propeller for a turboengine comprising a plurality of blades, a plurality of pivots, and a support ring of blades provided with housings each receiving a pivot bearing the foot of one of said blades,the propeller comprising a cleat placed between at least one of the pivots and the corresponding blade foot, the cleat being open-work to allow the discharge of ventilation airflow of the blade foot.2 2. The propeller as claimed in claim 1, the cleat comprising at least one discharge channel of the airflow intended to be located under the blade foot.3 3. The propeller as claimed in claim 2, said at least one discharge channel of the airflow comprising an axial discharge channel.4 4. The propeller as claimed in claim 2, said at least one discharge channel of the airflow comprising a lateral discharge channel.5 5. The propeller as claimed in claim 1, at least one of the pivots being equipped with at least one counterweight system provided with at least one inner discharge channel of the airflow intended to come into contact with the cleat.6 6. The propeller as claimed in claim 5, said at least one inner channel having an inner end which terminates on said at least one of the pivots and one at least of an introduction end and an ejection end of the airflow.7 7. The propeller as claimed in claim 1, the blades and / or said at least one counterweight system and / or the cleat and / or said at least one of the pivots being made of composite material.8 8. A turboengine comprising a propeller as claimed in claim 1.9 9. The turboengine as claimed in claim 8, said propeller being located downstream of a combustion chamber of said turboengine.1 10. The turboengine as claimed in claim 9, comprising a pair of open contrarotating propellers, each of the two propellers being as said propeller.

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