FLUID-TRANSFER DEVICE AND METHOD FOR MANUFACTURING SAME

Abstract

A fluid transfer device including a rotor having two centrifugal wheels, and a stator incorporating a set of continuous axi symmetric return channels conveying the fluid from the first wheel to the second wheel. Each of the return channels includes in succession a diffusing portion that guides the fluid in a centrifugal direction, a bend portion that redirects the fluid stream in a centripetal direction, a return portion that guides the fluid along a centripetal path, and then an outlet portion formed in a first non-tubular part that guides the fluid towards the second wheel. In these channels, the diffusing portion and the bend portion are distinct parts, and the diffusing portion is formed in a second non-tubular part secured to the first non-tubular part. A method of fabricating the device.

Claims

1-12. (canceled)

13. A fluid transfer device comprising a rotor having at least a first centrifugal wheel and a second centrifugal wheel, and a stator incorporating a plurality of return channels; in which device the return channels are axisymmetric, and each return channel includes in succession along the fluid flow path from the first wheel: a diffusing portion suitable for guiding the fluid stream in a centrifugal flow direction; then a bend portion suitable for redirecting the fluid stream in a centripetal flow direction; then a return portion suitable for guiding the fluid along a centripetal path; and then an outlet portion formed in a first non-tubular part, and suitable for guiding the fluid towards the inlet of the second centrifugal wheel; wherein each of said return channels is suitable for collecting a portion of a fluid stream leaving the first wheel and for directing this stream portion to an inlet of the second wheel without exchanging the fluid with any other one of said return channels; and in that for each of said channels: the diffusing portion and the bend portion are formed in distinct parts; and the diffusing portion is formed in a second non-tubular part secured to the first non-tubular part.

14. The device according to claim 13, wherein for each of said channels, the bend portion and/or the return portion is/are formed in one or more tubes.

15. The device according to claim 14, wherein for each of said channels, the bend portion and the return portion are formed in a single tubular part.

16. The device according to claim 13, wherein for each of said channels, the return portion is formed in a third non-tubular part

17. The device according to claim 16, wherein for each of said channels, the third non-tubular part and said first non-tubular part are formed in a single non-tubular part.

18. The device according to claim 16, wherein a union of said third non-tubular parts constitutes an assembly of one or more non-tubular parts forming an axisymmetric body extending over 360 around an axis of the device.

19. The device according to claim 17, wherein a union of said third non-tubular parts constitutes an assembly of one or more non-tubular parts forming an axisymmetric body extending over 360 around an axis of the device.

20. The device according to claim 13, wherein each of said channels has two tubular fractions formed in tubular parts, and a fourth non-tubular part is interposed between said tubular fractions.

21. The device according to claim 20, wherein for each of said channels, the fourth non-tubular part and said first non-tubular part are formed in a single non-tubular part.

22. The device according to claim 20, wherein a union of said fourth non-tubular parts constitutes an assembly of one or more non-tubular parts forming an axisymmetric body extending over 360 around an axis of the device.

23. The device according to claim 21, wherein a union of said fourth non-tubular parts constitutes an assembly of one or more non-tubular parts forming an axisymmetric body extending over 360 around an axis of the device.

24. The device according to claim 13, wherein a union of said first non-tubular parts and/or a union of said second non-tubular parts constitutes an assembly of one or more non-tubular parts forming an axisymmetric body extending over 360 around an axis of the device.

25. The turbomachine including at least one device according to claim 13.

26. The method of fabricating a fluid transfer device according to claim 13, wherein said diffusing portions are formed by any one of the following technologies: machining; electro-erosion of a forged or cast blank, or of a blank obtained by powder metallurgy or by additive fabrication; and/or direct forming using powder metallurgy, casting, or additive fabrication.

Description

[0065] The invention can be well understood and its advantages appear better on reading the following detailed description of embodiments shown as nonlimiting examples. The description refers to the accompanying drawings, in which:

[0066] FIG. 1A is a detail section view of a return channel of a fluid transfer device constituting a first embodiment of the invention;

[0067] FIGS. 1B, 1C, 1D, and 1E are detail section views of four variants of a return channel for fluid transfer devices constituting second, third, fourth, and fifth embodiments of the invention;

[0068] FIG. 2 is an axial half-section view of an example multistage high-power centrifugal turbopump fitted with a fluid transfer device in accordance with the invention, and including the return channels shown in FIG. 1A; and

[0069] FIG. 3 is a cross-section view of a transfer device in a sixth embodiment of the invention.

[0070] FIG. 2 shows a multistage turbopump 10 similar to various turbopumps used in cryogenic rocket engines known under the name Vulcain (registered trademark) and serving to feed such engines with liquid hydrogen at high pressure.

[0071] The turbopump 10 comprises a two-stage centrifugal pump 16 and a turbine 18 the drives the rotor of the pump 16 in rotation about an axis A.

[0072] The pump 16 constitutes a fluid transfer device in the meaning of the invention.

[0073] Inside a casing 12, the rotor of the pump 16 comprises a first centrifugal wheel 20 having blades 22, a second centrifugal wheel 30 having blades 32, an inducer 24, and a connection part 49.

[0074] The inducer 24, which imparts good suction characteristics and makes a high speed of rotation possible, is placed at the inlet of the pump 16 downstream from the duct (not shown) for admitting working fluid into the pump 16. The connection part 49 constrains the wheel 30 to rotate with the rotor of the turbine 18.

[0075] The inducer 24, the wheels 20 and 30, and the connection part 49 are stacked and clamped together axially by a tie bar or central shaft 40 of the pump 16.

[0076] The stator of the pump 16 includes the casing 12, and inside the casing, a set of fluid return channels 50. These channels pick up and slow down the fluid delivered by the wheel 20 and direct it towards the inlet of the wheel 30. The number of return channels may vary depending on the machine, and in general lies in the range 7 to 17.

[0077] In the pump 16, the working fluid is sucked in via the inducer 24; it is driven and compressed by the first bladed wheel 20; it is collected at the outlet from the wheel 20 by the fluid return channels 50. The working fluid is then driven and compressed once again by the second bladed wheel 30.

[0078] The fluid as compressed in this way is then collected at the outlet from the wheel 30 by a diffuser 34, which slows down the fluid before feeding the toroidal delivery duct 36.

[0079] The turbine 18 is arranged behind the second wheel 30 of the pump 16 (i.e. on the right-hand side of FIG. 2).

[0080] It comprises an admission torus 44 and a rotor mainly comprising two bladed turbine elements 42 and 43.

[0081] When the turbopump 10 is in operation, a stream of gas at high pressure penetrates into the turbine 18 via the torus 44 and passes in succession through the turbine elements 42 and 43, which it drives in rotation. Under the effect of the pressure exerted by the fluid on the turbine elements 42 and 43 as it passes through the turbine 18, these elements act via the connection part 49 to drive drive rotation of the the wheels 20 and 30 together with the inducer 24.

[0082] Thereafter, within the turbopump 10, the turbine portion 18 actuates the pump 16.

[0083] The main rotary portions of the machine, namely the inducer 24, the wheel 20, the wheel 30, the tie bar 40, and the turbine elements 42 and 43 are guided in rotation by rolling bearings 44 and 46. Relative to the axis A of the turbopump, the rolling bearing 44 is mounted between the wheel 20 and the wheel 30, and the rolling bearing 46 is mounted downstream from the wheel 30 in register with the connection part 49.

[0084] Inside the pump 16, and as mentioned above, reference 50 designates the various return channels that extend from the outlet of the first wheel 20 to the inlet of the second wheel 30.

[0085] These return channels are axisymmetric, i.e. each of them can be derived from the adjacent channel merely by turning about the axis A through an angle that depends on the total number of channels. For example, if the total number of channels is twelve, turning a channel about the axis A through 30 serves to obtain the adjacent channel.

[0086] Each of the return channels 58 presents four portions, namely a diffusing portion 52, a bend portion 54, a return portion 56, and an outlet portion 57.

[0087] The diffusing portions 52 are arranged within a non-tubular part 62 referred to as a hub, which provides the device with its structural integrity and its mechanical strength. This part 62 constitutes the second non-tubular part in the meaning of the invention, with this applying in like manner for all of the channels 50. Specifically, the part 62 is formed in integral or one-piece manner, and it extends over 360 about the axis A of the turbopump.

[0088] In a section containing the axis of rotation A of the device (FIG. 1A), the diffusing portions 52 extend in respective radial directions.

[0089] The outlet portion 57 of the channels are also arranged within the part 62, thereby limiting the number of parts in the turbomachine. The part 62 thus constitutes not only the second non-tubular part in the meaning invention, but also the first non-tubular part, and this applies to all of the channels 50.

[0090] Unlike the diffusing and outlet portions, the bend and return portions 54 and 56 of the return ducts 50 are formed by tubular parts that are distinct from the hub 62.

[0091] Each of the bend portions 54 is formed inside an independent tubular part 64. In the same manner, each of the return portions 56 is formed inside an independent tubular part 66.

[0092] It follows that the number of tubular parts 64, like a number of tubular parts 66, is equal to the total number of channels incorporated in the device 50. In a similar embodiment, the parts 64 and/or the parts 66 may be united to form a single part, extending over 360 around the axis A.

[0093] FIGS. 1B, 1C, 1D, and 1E show four other embodiments of the invention. They are identical to the first embodiment of the invention, apart from certain differences that are specified below. These differences lie in the way in which the various portions of the return channels 50 are made.

[0094] In these embodiments, parts that are identical or similar to the first embodiment are given the same numerical references.

[0095] In the second embodiment of the invention (FIG. 1B), the bend portion 54 and the return portion 56, instead of being formed as two distinct parts (tubes 64 and 66) as in FIG. 1A, are formed in a single tubular part 164. This variant makes it possible to be unaffected by potential problems at the connections between the tubular parts 64 and 66, as shown in FIG. 1A. In contrast, it can lead to greater difficulty in making the part 164 compared with parts 64 and 66 that are made separately.

[0096] In the third embodiment (FIG. 1C), a fraction 58 of the return portion 56 of each of the channels is formed in a non-tubular part (which constitutes a fourth non-tubular part in the above-defined meaning), arranged between two tubular parts or portions.

[0097] This fourth non-tubular part is constituted by the part 62 that also has formed therein, for each of the channels, the diffusing portion 52 and the outlet portion 57.

[0098] The return portion 56 is thus made up of two fractions: [0099] an upstream fraction 58 formed in the part 62 and connected upstream to the outlet orifice from the bend portion 54 formed in a tube 64; [0100] a downstream fraction 59 formed in a tube 66 connected upstream to the outlet orifice of the upstream fraction 58.

[0101] The advantage of this variant is to deal with potential problems at the connection between the tubular parts 64 and 66 as shown in FIG. 1A.

[0102] In the fourth embodiment (FIG. 1D), the return portion 56 is constituted by a third non-tubular part in the above-defined meaning. Like the diffusing portion 52 and the outlet portion 56, it is formed in the part 62. Under such circumstances, the return portion 56 is formed integrally (as a single piece) with the outlet portion 57, within the part 62. Although this variant may lead to the return portion and the outlet portion possibly being more complex to make (e.g. by machining or by electro-erosion), it makes it possible, conversely, to avoid or at least limit potential problems with connections between the tubular parts 64 and 66 as shown in FIG. 1A.

[0103] In all of the above described embodiments, it is possible in a similar embodiment for the first non-tubular part in which the outlet portion is formed, and the tubular part in which the diffusing portion is formed to be made as distinct parts, that are secured to each other. The part 62 shown in FIGS. 1A to 1D is then replaced by at least two parts.

[0104] The fifth embodiment (FIG. 1E) illustrates this possibility. In this embodiment, the first tubular portion is formed by a first non-tubular part 162. The second tubular part is formed by a second non-tubular part 163 that is rigidly fastened to the part 162 by means that are not shown, e.g. by welding.

[0105] In all of the above described embodiments, the tubes 64, 66, and 164 are thin-walled tubes.

[0106] Finally, FIG. 3 shows a sixth embodiment presenting a possible arrangement, in particular for the non-tubular parts.

[0107] This arrangement is shown for the second non-tubular part, but it could equally well be applied to one or more of the first, third, and fourth non-tubular parts.

[0108] The sixth embodiment is identical to the first embodiment (FIG. 1A) apart from the following difference.

[0109] In the first embodiment, the part 62 extends over 360 around the axis A; the diffusing (and outlet) portions of all of the channels are formed in the part 62.

[0110] Nevertheless, the part 62 may be subdivided into a plurality of distinct fractions that are arranged in axisymmetric manner around the axis A: for example four fractions, each occupying an angular sector of 90 around the axis.

[0111] This embodiment is shown in FIG. 3. It represents a cross-section of the transfer device perpendicularly to the axis A, axially level with the bend portion 54.

[0112] In this embodiment, the device comprises four distinct parts 62A, 62B, 62C, and 62D, all having the same shape. These parts are assembled around the axis A, each occupying a quadrant so as to form an axisymmetric body.

[0113] The axisymmetric body has the same shape and the same function as the parts 62 shown in FIG. 1A but it is made up of four parts 62A, 62B, 62C, and 62D instead of being formed by a single part; it has the same reference 62 as the part 62.