WO2018078239A1

WO2018078239A1 - Impeller for centrifugal pump, centrifugal pump and manufacturing method

Info

Publication number: WO2018078239A1
Application number: PCT/FR2017/052832
Authority: WO
Inventors: Laurent Fabbri; Alban Lemaitre; Antoine Alain Gaston MERY
Original assignee: Arianegroup Sas
Priority date: 2016-10-27
Filing date: 2017-10-16
Publication date: 2018-05-03
Also published as: EP3532732A1; EP3532732B1; FR3058190B1; FR3058190A1

Abstract

The invention relates to an impeller (10) for a centrifugal pump having an axial direction (X), the impeller (10) comprising a hub (24), a web (26) having a rotationally symmetrical shape comprising an attachment part (28) for attaching the web (26) to the hub (24), the web (26) widening from the attachment part (28) in the axial direction (X), and an annular bead (30) arranged between the web (26) and the hub (24), the annular bead (30) being attached to the web (26) while an annular space (32) is created between the hub (24) and the annular bead (30). The invention also relates to a centrifugal pump comprising the impeller (10) and a method for manufacturing the impeller (10).

Description

CENTRIFUGAL PUMP WHEEL, CENTRIFUGAL PUMP AND METHOD OF

MANUFACTURING

Background of the invention

The present disclosure relates to a centrifugal pump, in particular for a turbomachine.

In rocket engines, aircraft or helicopter, an important aspect is the mass of the various constituent elements of the engine.

However, the mass reduction is often to the detriment of the mechanical strength or fatigue strength of the various elements, so that each element is generally a compromise between the mass and the mechanical strength of the element.

This is the case for example of a centrifugal pump wheel which must have good hydraulic performance and also good mechanical strength on the shaft so that the torque can be transmitted from the rotating shaft to the wheel centrifugal pump.

For this purpose, typically, the wheel is shrunk on the shaft by an element of the wheel called tail rotor which must ensure the good transmission of torque between the wheel and the shaft even at high speeds of rotation undergone by the wheel of the centrifugal pump.

Also, when some parts have several functions, we understand that their optimization can become difficult.

However, it is still sought to optimize such centrifugal pumps in particular to reduce their mass while maintaining their hydraulic performance and mechanical strength.

Object and summary of the invention

The present disclosure aims to provide a centrifugal pump whose mass is reduced compared to known centrifugal pumps and which has hydraulic performance and mechanical strength at least equivalent to known centrifugal pumps.

For this purpose, the present disclosure relates to a wheel for centrifugal pump having an axial direction, the wheel comprising a hub, a veil having a shape of revolution comprising a fixing part. of the web with the hub, the web flaring from the fastening portion in the axial direction, and an annular bead disposed between the web and the hub, the annular bead being attached to the web while an annular space is provided between the hub and the annular bead.

With this annular space between the hub and the annular bead, the hub does not undergo centrifugal force exerted by the web on the hub when the wheel is rotating. Also, when the wheel is rotating about the axial direction, the deformation undergone by the hub is relatively small and less important than the deformation undergone by a hub on which a web would be directly attached.

It is therefore understood that in a plane perpendicular to the axial direction passing through the web and the annular bead, the annular bead is disposed between a central axis of the wheel and the web, the annular space being present between the annular bead. , and therefore a part of the veil, and the hub or a projection of the hub on the perpendicular plane.

Furthermore, the structural integrity of the web and the wheel is ensured by the presence of the annular bead fixed on the web, between the web and the hub. This annular bead has a dimension in the axial direction which is greater than the thickness of the veil, the thickness of the veil being measured perpendicularly to the main surfaces of the veil.

This annular bead therefore makes it possible to limit the displacements in a radial direction at the output of the wheel and also makes it possible to control the displacements in the axial direction. The annular bead corresponds to a thickening in the ring-shaped material direction. It is understood that the shape and / or the dimensions of the annular bead can be modified in order to adapt the rotational behavior of the wheel, in particular as a function of rotational speeds in operation of the wheel. Indeed, if the maximum displacements in service in the radial and axial directions are of low amplitude, for example less than 100 μπι, it is possible to reduce the dimensions of the annular bead. Displacements in the radial and axial directions may depend for example on the diameter of the wheel, the speed of rotation, the intrinsic properties of the material in which the wheel is made, such as the density. However, in particular thanks to simulation software (for example by finite element), it is possible to modify the shape and / or the dimensions of the annular bead. The veil flaring from the attachment portion of the web in the axial direction, there is a cavity formed between the hub, the web and the annular bead. This cavity is at least open towards the outside because of the annular space formed between the hub and the annular bead. As a result, the mass of the wheel is less than the mass of a wheel that does not have this open cavity.

It is understood that the web is attached to the hub by the fastening portion of the web and that the fastening portion of the web and the hub forms the bottom of the open cavity, the bottom of the open cavity being disposed downstream the annular space between the hub and the annular bead.

It is understood that the wheel is made in one piece, that is to say that the hub, the web and the bead are not assembled to each other.

The wheel may comprise an upstream end and a downstream end, the fixing portion of the web with the hub being disposed at the upstream end of the wheel and the annular bead being disposed at the downstream end of the wheel.

Subsequently, the terms "upstream" and "downstream" are defined relative to the normal flow direction of the fluid in the centrifugal pump.

By upstream end of the wheel is meant a portion of the wheel located upstream of the wheel and whose dimension, in the axial direction, is less than or equal to 50% of the total length of the wheel, in the axial direction. Similarly, the term "downstream end of the wheel" is understood to mean a part of the wheel located downstream of the wheel and whose dimension, in the axial direction, is less than or equal to 50% of the total length of the wheel, in the axial direction.

The hub may comprise an inner shrinking surface configured to shrink the hub on a shaft, the inner hooping surface being arranged, at least in part, in the axial direction, to the right of the annular space formed between the hub and the annular bead.

It is understood that in an axial sectional view of the wheel, when projecting the section of the annular bead on the inner surface of the hub in a radial direction, defining a section of the inner surface of the hub which is, according to the axial direction, to the right the annular space formed between the hub and the annular bead and therefore, in the axial direction, to the right of the annular bead.

Therefore, even when the wheel is mounted on the shaft and rotates at high speed, the hoop between the shaft and the hub undergoes little or no deformation.

Also, unlike known wheels, it is no longer necessary to provide a tail wheel as long in the axial direction and offset from the web downstream of the wheel in the axial direction. Indeed, in wheels having no annular space around the hub, the inner surface of the hub shrinking is disposed downstream of the web so that the centrifugal forces exerted by the mass of the wheel on the inner surface of the hub , in particular by the end of the wheel farthest radially from the axis of rotation of the wheel, do not deform the internal hooping surface.

It is therefore possible to move the hooping surface upstream of the wheel. It is thus possible to reduce the length of the wheel shank, to reduce the mass of the wheel and its bulk, ie the total dimension of the wheel in the axial direction. As a result, the mass gain goes beyond the mass gain of the wheel. In fact, it is also possible to reduce the mass of the casings of the centrifugal pump as well as the mass of the casings surrounding the centrifugal pump.

Moreover, the internal shrinking surface being little or no deformed during the rotation of the wheel, the shrinking of the wheel on the shaft is facilitated. Indeed, the inner diameter of the inner hooping surface is dimensioned at rest taking into account the maximum deformation under stress experienced by the inner hooping surface. Since this deformation is small, the inside diameter of the inner hoop-resting surface is therefore slightly smaller than the inside diameter of the inner hooping surface during the rotation of the wheel. The force required to assemble the shaft and the wheel is therefore limited with respect to the force required to assemble a wheel having no annular space formed between the annular bead and the hub and whose difference in internal diameter of the inner surface of hooping between the rest and the rotation of the wheel is significant. For example, for a hub having a diameter of 27 mm (millimeter), with a conventional wheel, the maximum displacement in use can reach 0.2 mm in the shrinking zone, whereas with a wheel as defined above, the maximum displacement in use is only 0.02 mm in the hooping zone.

The inner hooping surface may be substantially completely disposed in the axial direction to the right of the annular space formed between the hub and the annular bead.

We can design a wheel does not include spinning wheel.

By substantially completely arranged, in the axial direction, the right of the annular space formed between the hub and the annular bead means that the inner shrinking surface is included in the radial projection of the annular bead on the inner surface of the hub, at plus or minus 5% the radial projection of the annular bead on the inner surface of the hub.

Thus, the inner hooping surface may be smaller than the radial projection of the annular bead on the inner surface of the hub but slightly exceed, less than 5% of the dimension, in the axial direction of the annular bead.

The hub may comprise an inner shrinking surface (38) configured to shroud the hub on a shaft, the inner hooping surface being arranged, in the axial direction, upstream of the annular space formed between the hub and the annular bead.

It is thus possible to reduce the mass of the wheel.

The wheel may comprise a plurality of reinforcing ribs disposed between the web and the hub.

These reinforcing ribs increase the mechanical strength of the wheel while limiting the overall mass of the wheel. These reinforcing ribs may have a purely radial direction, they may also be inclined relative to the radial direction. Thus, by modifying the number, the location and / or the dimensions of the reinforcing ribs, it is possible to modify the rigidity of the wheel. These reinforcing ribs may also allow the transmission of torque between the shaft and the wheel, in particular between the shaft and the wheel web.

The web may comprise a plurality of through orifices. These through holes allow a pressure equalization between an upstream surface of the web and a downstream surface of the web. It is thus possible to balance the forces on the shaft upstream and downstream of the wheel and thus reduce the sudden forces by stops of the centrifugal pump.

The wheel may comprise an inductor and an impeller and the through orifices are disposed between the inductor and the impeller allowing orientation of the fluid in the axis of the flow.

The wheel can be made of metal or metal alloy.

The present disclosure also relates to a centrifugal pump comprising a wheel as defined above.

The present disclosure also relates to a method of manufacturing a wheel as defined above, the wheel being made by an additive manufacturing process.

This additive manufacturing process allows great flexibility in the shapes produced and also makes it easy to produce parts with cavities and / or internal ducts.

Brief description of the drawings

Other features and advantages of the invention will emerge from the following description of embodiments of the invention, given by way of non-limiting examples, with reference to the appended figures, in which:

- Figure 1 is a schematic axial sectional view of a centrifugal pump;

- Figures 2A and 2B are views in axial section of a wheel for a centrifugal pump according to two embodiments;

FIG. 3 is a perspective view of the wheel of FIG. 2A, seen from the upstream side; and

- Figure 4 is a partial perspective view of the wheel of Figure 2A, seen from the downstream side.

Detailed description of the invention FIG. 1 represents an axial sectional view of a centrifugal pump 100 comprising a shaft 12, defining an axis X, on which are mounted a wheel 10, an impeller turbine nozzle 116 and a turbine disk 102. These FIG. elements are included in a pump housing 104 which has a front housing 106, a central housing 108 and an exhaust housing 110. The pump housing 104 defines a pump volute 112 and a turbine inlet core 114.

The pump 100 also comprises locking means along the axis X of the elements of the pump 100 on the shaft 12. These elements are for example nuts 14 and 118. The wheel 10 and the turbine disc 102 are mounted on the shaft 12 and in the pump casing 104 by bearings 18, the wheel 10 and the turbine disc 102 being each spaced from their respective bearing 18 by a shim 16.

FIG. 2A shows an embodiment of a wheel 10 for a centrifugal pump 100. In FIG. 2A, the arrow F represents the normal flow direction of a fluid in the centrifugal pump 100 and therefore around the wheel 10. Thereafter, the terms "upstream" and "downstream" are defined relative to the direction of normal circulation of the fluid in the centrifugal pump.

The wheel 10 is shown mounted on the shaft 12. It is fixed on the shaft 12, at its upstream end, by the nut 14 and, at its downstream end, by the shim 16 and the bearing 18.

In general, the wheel 10 of FIG. 2A comprises an inductor 20 and an impeller 22.

The wheel 10 comprises an axis of rotation X defining an axial direction X of the wheel 10.

The wheel 10 comprises a hub 24 and a sail 26 having a shape of revolution comprising an attachment portion 28 of the web 26 with the hub 24. As shown, the web 24 flares from the fastening portion 28 according to the X axial direction, that is to say that the web 26 flares from the fastening portion 28, disposed at an upstream end of the wheel 10 to a downstream end of the wheel 10. In Figure 2A, the veil 26 has a first portion of substantially cylindrical shape which then flares downstream of the wheel 10, so that a free end 26A of the web extends substantially in a radial plane, that is to say in a plane perpendicular to the axial direction X. The wheel 10 also comprises an annular bead 30 disposed between the web 26 and the hub 24, at the downstream end of the wheel 10, to the right, in the axial direction X, of the free end 26A of the sail 26 The annular bead 30 is fixed to the web 26 while an annular space 32 is formed between the hub 24 and the annular bead 30.

The web 26 flaring from the attachment portion 28 of the web 26 in the axial direction X, a cavity 34 is thus formed between the hub 24, the web 26 and the annular bead 30. This cavity 34 is at less open because of the annular space 32 formed between the hub 24 and the annular bead 30.

Furthermore, in the embodiment of Figure 2A, the hub 24 has an inner surface 36. This inner surface 36 has a portion which forms an inner shrinking surface 38 of the hub 24 and thus the wheel 10 on the shaft 12. This inner hooping surface 38 is disposed at the downstream end of the wheel 10.

The radial projection, that is to say in a radial direction R, of the section of the annular bead 30 on the hub 24, in particular on the inner surface 36 of the hub 24, defines a portion of the inner surface. 36, in the axial direction X, to the right of the annular space 32 formed between the hub 24 and the annular bead 30.

In the embodiment of FIG. 2A, the inside hooping surface 36 is arranged substantially completely, in the axial direction X, at the level of the annular space 32 formed between the hub 24 and the annular bead 30.

The inner hooping surface 38 is included in the radial projection of the annular bead 30 on the inner surface 36 of the hub 24, plus or minus 5% the radial projection of the annular bead 30 on the inner surface 36 of the hub 24. Thus, the internal hooping surface 38 may be smaller than the radial projection of the annular bead 30 on the inner surface 36 of the hub 24 but slightly exceed, by less than 5% of the dimension, in the axial direction X of the annular bead. 30.

The wheel 10 comprises a plurality of reinforcing ribs 40 for reinforcing disposed between the web 26 and the hub 24 in the cavity 34. These radial ribs 40 are also visible in FIG. 4. 17 052832

9

As shown in Figures 2 to 4, the web 26 has a plurality of through holes 42 disposed between the inductor 20 and the impeller 22. These through holes 42 allow the passage of liquid from the upstream of the wheel 10 in the cavity 34. As shown in Figure 4, each through hole 42 opens between two reinforcing ribs 40.

Furthermore, the inductor 20 comprises fins 44, in this embodiment the inductor 20 comprises four fins 44 and the impeller 22 comprises fins 46, in this embodiment the wheel comprises twelve fins 46.

Note that the reinforcing ribs 40 are also 12 in number and that they are arranged vis-à-vis on both sides of the web 26.

Furthermore, the inner surface 36 of the hub 24 has projections 48 also allowing the passage of the torque between the shaft 12 and the hub 24.

In the following, the elements common to the various embodiments are identified by the same reference numerals.

In the embodiment of FIG. 2B, the inner hooping surface 36 is arranged substantially completely, in the axial direction X, upstream of the annular space 32 formed between the hub 24 and the annular bead 30.

The wheel 10 is manufactured by an additive manufacturing process, for example by using a laser beam on a bed of powder. The powder bed is formed by the powder that will constitute the wheel 10. For example, the powder may comprise titanium or be a metal alloy commonly referred to by the trademark Inconel ™. Inconel is later referred to as an alloy based on iron alloyed with nickel and chromium.

The wheel 10 is manufactured by superposition of layers in the axial direction X from its downstream end and ending with its upstream end.

The outer surfaces of the wheel 10 are then machined in a conventional manner and known so that the surface condition of the web 26, the fins 44, 46 and the inner surface 36 of the hub is in accordance with the 52832

10

Specifications. It is not necessary to machine the surfaces of the cavity 34.

Although the present description has been described with reference to a specific embodiment, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In addition, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

For example, the number of fins 44 carried by the inductor 20 may vary, the same is true of the number of fins 46 carried by the impeller 22. The number of reinforcing ribs 40 may be different from the number of fins 46 carried by the impeller 22. Similarly, the number of through holes 42 may be different from the number of reinforcing ribs 40.

Note also that the fins 44, 46 are straight fins, these fins may also be inclined relative to the radial direction, or even have a certain curvature. The same is true of the reinforcing ribs 40. The reinforcing ribs 40 shown are radial ribs. However, these ribs may also be inclined relative to the radial direction, or even have a certain curvature. The wheel 10 comprises an inductor 20 and an impeller 22. The wheel 10 could comprise only one impeller 22.

Claims

A centrifugal pump wheel (10) having an axial direction (X), the wheel (10) comprising a hub (24), a web (26) having a shape of revolution comprising an attachment portion (28) of the web ( 26) with the hub (24), the web (26) flaring from the fastening portion (28) in the axial direction (X), and an annular bead (30) disposed between the web (26) and the hub (24), the annular bead (30) being attached to the web (26) while an annular space (32) is provided between the hub (24) and the annular bead (30).

The wheel (10) of claim 1, wherein the wheel (10) includes an upstream end and a downstream end, the veil attachment portion (28) with the hub (24) being disposed at the upstream end of the wheel (10). the wheel (10) and the annular bead (30) being disposed at the downstream end of the wheel (10).

A wheel (10) according to claim 1 or 2, wherein the hub (24) has an inner shrinking surface (38) configured to shroud the hub (24) on a shaft (12), the inner hooping surface ( 38) being arranged, at least in part, in the axial direction (X), to the right of the annular space (32) formed between the hub (24) and the annular bead (30).

A wheel (10) according to claim 3, wherein the inner hooping surface (38) is substantially completely disposed in the axial direction (X) to the right of the annular space (32) between the hub (24). ) and the annular bead (30).

The wheel (10) according to claim 1 or 2, wherein the hub (24) has an inner shrinking surface (38) configured to shroud the hub (24) on a shaft (12), the inner hooping surface ( 38) being arranged, in the axial direction (X), upstream of the annular space (32) formed between the hub (24) and the annular bead (30).

Wheel (10) according to any one of claims 1 to 5, wherein the wheel (10) has a plurality of reinforcing ribs (40) disposed between the web (26) and the hub (24).

Wheel (10) according to any one of claims 1 to 6, wherein the web (26) has a plurality of through holes (42).

Wheel (10) according to claim 7, wherein the wheel (10) comprises an inductor (20) and an impeller (22) and in which the through holes (42) are arranged between the inductor (20) and the impeller (22).

9. Centrifugal pump comprising a wheel (10) according to any one of claims 1 to 8.

10. A method of manufacturing a wheel (10) according to any one of claims 1 to 8, the wheel (10) being performed by an additive manufacturing process.