Distributor for a turbomachine radial turbine, turbomachine comprising such a distributor and air conditioning system comprising such a turbomachine

Abstract

The invention relates to a distributor for a turbomachine radial turbine, comprising an annular grill (26) extending about a central axis (10) and comprising a plurality of variable-pitch blades (31), defining between them an air passage cross section, characterized in that each blade is rotatably mounted about a pivot shaft (32), itself moveable in a translation direction, comprising at least one radial component, such that said blade may, upon actuation of control means (40), be pivoted about the pivot shaft and/or moved in relation to the central axis in said translation direction so as to be able to modify the air passage cross section by respectively controlling the metal angle (α3) and the radial spacing (ΔR).

Claims

1. A distributor assembly of a turbomachine radial turbine comprising a rotor equipped with vanes adapted to be rotated about a central axis, said distributor comprising an annular grill extending about said central axis, arranged on the periphery of said rotor and comprising a plurality of variable-pitch blades arranged about said central axis delimiting between the blades a passage cross section of an air stream from said distributor to said rotor, each of the blades further extending in a main direction and having a leading edge and a trailing edge arranged opposite the leading edge on the rotor vanes, wherein each variable-pitch blade is mounted to be rotatably movable about a pivot shaft extending parallel to the central axis, the pivot shaft being movable relative to the central axis in a translation direction comprising at least one radial component, so that each corresponding one of the blades, upon actuation of control means, pivoted about the pivot shaft or moves relative to the central axis in said translation direction so as to be able to modify said passage cross section of the air stream from upstream to downstream of the distributor, by controlling respectively a metal angle formed between the main direction of the corresponding one of the blades and the radial direction, and the radial spacing which separates the trailing edge of the corresponding one of the blades and the leading edge of the rotor vanes; wherein said pivot shaft of each corresponding one of the blades is mounted to be movable in radial translation with respect to the central axis so that said translation direction coincides with the radial direction.

2. The distributor according to claim 1, wherein said control means of said blades are configured to be able to control, for each corresponding one of the blades, the pivoting of the corresponding one of the blades about its pivot shaft concomitantly with the movement of the corresponding one of the blades in said translation direction.

3. The distributor according to claim 1, wherein said control means of each corresponding one of the blades comprises mechanical axle return means making it possible to move said corresponding one of the blades according to a radial translation of said blade.

4. The distributor according to claim 1, wherein said control means of said blades are configured to be able to keep, for each corresponding one of the blades, and for any position of the pivot shaft of the corresponding one of the blades, the coefficient E1=ΔR/H.Math.cos(3f) constant, where ΔR defines the radial spacing between the trailing edge of the corresponding one of the blades and the leading edge of the rotor vanes, 3f defines the angle formed between the direction of air flow at the trailing edge of the corresponding one of the blades and the radial direction, and H defines the height, in the direction of the central axis, of the air stream.

5. The distributor according to claim 1, wherein the distributor comprises at least thirteen of the blades which are evenly distributed about the central axis.

6. A turbomachine radial turbine extending along a central axis and comprising a rotor equipped with vanes mounted to be rotatably movable about said central axis, a distributor arranged on the periphery of said rotor comprising a plurality of variable-pitch blades, and a volute comprising an air inlet and an air outlet opening onto said plurality of variable-pitch blades, wherein said distributor is a distributor comprising: the plurality of variable-pitch blades arranged about said central axis delimiting between the plurality of variable-pitch blades a passage cross section of an air stream from said distributor to said rotor, each of the variable-pitch blades further extending in a main direction and having a leading edge and a trailing edge arranged opposite the leading edge on the rotor vanes, wherein each variable-pitch blade is mounted to be rotatably movable about a pivot shaft extending parallel to the central axis, the pivot shaft being movable relative to the central axis in a translation direction comprising at least one radial component, so that the each variable-pitch blade, upon actuation of control means, pivots about the pivot shaft and/or moves relative to the central axis in said translation direction so as to be able to modify said passage cross section of the air stream from upstream to downstream of the distributor, by controlling respectively a metal angle formed between the main direction of the variable-pitch blade and the radial direction, and the radial spacing which separates the trailing edge of the variable-pitch blade and the leading edge of the rotor vanes; wherein said pivot shaft of each variable pitch blade is mounted to be movable in radial translation with respect to the central axis so that said translation direction coincides with the radial direction.

7. An air conditioning system for an aircraft comprising a turbomachine comprising at least one turbine and one compressor, wherein said turbine is a radial turbine extending along a central axis and comprising a rotor equipped with vanes mounted to be rotatably movable about said central axis, a distributor arranged on the periphery of said rotor comprising a plurality of variable-pitch blades, and a volute comprising an air inlet and an air outlet opening onto said plurality of variable-pitch blades, wherein said distributor is a distributor comprising: the plurality of variable-pitch blades arranged about said central axis delimiting between the plurality of variable-pitch blades a passage cross section of an air stream from said distributor to said rotor, each of the variable-pitch blades further extending in a main direction and having a leading edge and a trailing edge arranged opposite the leading edge on the rotor vanes, wherein each variable-pitch blade is mounted to be rotatably movable about a pivot shaft extending parallel to the central axis, the pivot shaft being movable relative to the central axis in a translation direction comprising at least one radial component, so that the variable-pitch blade, upon actuation of control means, pivots about the pivot shaft and/or moves relative to the central axis in said translation direction so as to be able to modify said passage cross section of the air stream from upstream to downstream of the distributor, by controlling respectively a metal angle formed between the main direction of the variable-pitch blade and the radial direction, and the radial spacing which separates the trailing edge of the blade and the leading edge of the rotor vanes; wherein said pivot shaft of each variable pitch blade is mounted to be movable in radial translation with respect to the central axis so that said translation direction coincides with the radial direction.

Description

LIST OF FIGURES

(1) Further objects, features and advantages of the invention will become apparent upon reading the following description, which is provided solely by way of non-limiting example, and which refers to the appended figures, in which:

(2) FIG. 1 is a schematic perspective view of a turbine according to one embodiment of the invention equipped with a distributor according to one embodiment of the invention,

(3) FIGS. 2a and 2b are partial schematic views of a distributor illustrating the movement of a blade both in pivoting and in radial translation, making it possible to modify independently the fluid angle α3f and radial spacing ΔR,

(4) FIG. 3 is a schematic perspective view of a blade of a distributor according to one embodiment of the invention,

(5) FIG. 4 is a partial schematic cross-sectional view of the distributor according to one embodiment of the invention in a longitudinal plane of the turbine along its axis of rotation,

(6) FIG. 5 is a schematic perspective view of a turbine impeller and of a turbine distributor according to one embodiment of the invention.

DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

(7) For the sake of illustration and clarity, the scales and proportions are not strictly adhered to in the figures. Throughout the detailed description which follows with reference to the figures, unless otherwise indicated, each element of the distributor is described as it is arranged when the distributor is mounted on a turbine. This arrangement is shown in particular in FIG. 1.

(8) Moreover, identical, similar or analogous elements are denoted using the same references throughout the figures.

(9) FIG. 1 schematically illustrates a radial turbine according to one embodiment of the invention which extends along a central axis 10 and comprises an impeller 20 that is rotatably movable about the central axis 10 and a distributor 30 arranged on the periphery of the impeller 20 on a casing 11 (of which only a half-casing is shown in FIG. 1). The impeller 20 is equipped with a plurality of vanes 21.

(10) The turbine also comprises a volute 12 (of which a half-volute is shown in FIG. 1), the diameter of which decreases between an inlet 12a and an outlet 12b which opens onto the distributor 30.

(11) The distributor 30 also comprises an annular grill 26 which extends about a central axis 10 and a plurality of variable-pitch blades 31, each variable-pitch blade 31 being integral with a pivot shaft 32 which extends parallel to the central axis 10.

(12) FIG. 5 schematically illustrates, in perspective, the impeller 20 and the distributor 30 of the turbine according to one embodiment.

(13) Each pivot shaft 32 is housed in a guide slot 33 of the blade shaft. This guide slot 33 extends in the radial direction, which forms the translation direction of the blade 31, in the embodiment of FIG. 5. Thus, the blade 31 may be pivoted about the pivot axis formed by the pivot shaft 32 and/or moved in the air stream by the sliding of the pivot shaft 32 in the guide slot 33.

(14) Naturally, other means may be implemented to provide the radial movement of the pivot shaft. These means may thus, for example, comprise an axle return mechanism making it possible to provide a radial translation of the blade 31.

(15) In FIGS. 1 and 5, and for each blade 31, the pivot shaft 32 of the blade is shown in the vicinity of the leading edge of the blade. Naturally, according to other embodiments, this pivot shaft 32 may be arranged elsewhere on the blade 31, in particular in the vicinity of the trailing edge of the blade, in the center of the blade, and generally at any point on the blade. The position of the pivot shaft 32 depends on the specifications targeted by the distributor according to the invention.

(16) FIG. 3 illustrates schematically, and in more detail, a blade 31 integral with its pivot shaft 32, itself movable in radial translation in a guide slot 33.

(17) The movement principle of the blades 31 of the distributor according to the invention is also evident from FIGS. 2a and 2b which schematically illustrate a blade 31 of a distributor according to another embodiment of the invention and a vane 21 of a rotor of a turbomachine arranged facing this blade 31. The metal angle α3 defines the angle formed between the main direction 34 of the blade 31 and the radial direction 24 along which extends a vane 21 of the rotor.

(18) The fluid angle α3f defines the angle formed between the flow direction of the fluid at the trailing edge of the blade 31, represented by an arrow referenced Fl in FIG. 2a, and the radial direction 24 along which extends the vane 21 of the rotor. Finally, the radial spacing ΔR defines the distance between the trailing edge of the blade 31 and the leading edge of the vane 21 of the rotor.

(19) Each blade 31 is further mounted movable in radial translation in a radial guide slot 33 by sliding the pivot shaft 32 of the blade 31 in this guide slot.

(20) FIG. 2a shows the blade 31 in a first position characterized by a given fluid angle α3f and a given spacing ΔR. This configuration corresponds to the positioning of the pivot shaft 32 of the blade 31 at a first radial end of the guide slot. This arrangement minimizes the radial spacing ΔR, hence the label ΔRmin in FIG. 2a. In FIG. 2b, the pivot shaft of the blade 31 is arranged at the opposite radial end of the guide slot 33. This arrangement maximizes the radial spacing ΔR, hence the label ΔRmax in FIG. 2b. In the case where the guide slot extends in the radial direction, the length of the slot defines the difference between ΔRmax and ΔRmin.

(21) Moreover, in the configuration of FIG. 2b, the blade 31 is pivoted relative to the configuration of FIG. 2a. The dotted line blade of FIG. 2b represents the blade 31 in the configuration of FIG. 2a in order to demonstrate the change in angle and radial position of the blade in the configuration of FIG. 2b.

(22) The invention therefore makes it possible to impose on each blade 31 of the distributor an opening/closing angle and a radial position of the pivot shaft 32 of the blade 31. In particular, any intermediate configuration between the two extreme configurations (with regard to the radial position of the pivot point) shown in FIGS. 2a and 2b is permitted by a distributor according to the invention.

(23) In FIGS. 2a and 2b, only a few blades are shown, it being understood that in practice, each blade may be moved both in pivoting about its pivot shaft and in radial translation.

(24) The invention makes it possible in particular to keep the coefficient E1=ΔR/H.Math.cos(α3f) constant by a control depending on the fluid angle α3f and the spacing ΔR of the different blades 31 of the distributor.

(25) FIG. 4 schematically illustrates the blade 31 and the control means 40 for adjusting the blade. These control means 40 comprise for example a shaft 41 which is mechanically connected to the shaft 32. This mechanical connection may for example comprise arms, pinions, bearings connected to electric or electromagnetic actuators 42, making it possible to mechanically connect the control shaft 41 and the movement shaft 32 of the blade 31. According to a preferred embodiment, a single actuator may be configured for all of the blades 31 of the distributor.

(26) The actuators 42 are controlled by a central control unit 50, which may be of any type.

(27) A distributor according to the invention is particularly intended to equip a turbine of an air conditioning system of an aircraft.

(28) Such an air conditioning system typically also comprises a set of members enclosed in a casing and having air inlet and outlet connection ports and a dynamic air circulation channel, better known as RAM air, through one or more heat exchangers. Such a pack may be the subject of numerous variant embodiments which are compatible with the invention. For example, it may comprise at least one air cycle turbomachine which comprises a compressor and a turbine connected to one another by a rotating shaft. The turbomachine may also comprise a fan configured to ensure dynamic air circulation through the heat exchangers. According to another variant, the turbomachine may comprise an electric motor so as to form an electric air conditioning pack. The pack may also comprise a water extraction loop and a turbomachine outlet duct connected to a mixing chamber which opens into the cabin to be supplied with air at a controlled temperature and pressure. The turbine of the air cycle machine is, according to the invention, equipped with a distributor according to the invention, which allows the turbine to provide a wide range of air flow rates while delivering the most power possible over the entire operating range.

(29) The principle of the invention could also be applied to a variable diffuser of a centrifugal compressor.

(30) The invention has been described particularly for an aeronautical application. That said, the invention could also apply to an air conditioning system implemented in a motor vehicle, for example for an air supply system for a fuel cell.

(31) The invention could also be applied to an air conditioning system for a railway vehicle and in general to any technical field requiring a modification of the injection cross section over a wide flow rate range.