FR3081192A1 - IMPROVED FLUID TRANSFER DEVICE FOR SPACE ENGINE - Google Patents

Abstract

A fluid transfer device comprising a pump configured to compress a fluid, the pump having a pump body (12) and at least one impeller inside the pump body (12), arranged around a central axis , a diffuser (34) for receiving and redirecting the fluid discharged by the impeller, and a fluid collector (36) arranged around the pump body (12) and the diffuser (34) and configured to collect the outgoing compressed fluid of the diffuser (34), in which, in a section passing through the central axis, the collector (36) has two ends each connected to the pump body (12), and between them, a central part (363) presenting a substantially oval shaped inner surface, a first joining portion (361) and a second joining portion (362), the first and second joining portions (361, 362) connecting the central portion (363) to the ends of the collector (36), the central part (363) and the parts connecting piece (361, 362) having, between the ends, a capacity to deform such that, during a nominal operation of the device, a maximum mechanical stress in the diffuser (34) is less than a maximum mechanical stress in the manifold (36 ).

Description

FIELD OF THE INVENTION The invention relates to the field of rocket engines and satellites, and more particularly to the casings of space turbopumps, and to the transfer of forces within this casing.

STATE OF THE PRIOR ART [0002] Space turbopumps generally comprise a centrifugal pump comprising a rotor having at least a first and a second wheel, possibly centrifugal, and, when there is a plurality of centrifugal wheels, a stator incorporating a plurality return channels. In the pump, a working fluid is driven and compressed by the first centrifugal impeller, collected downstream by the return channels, then, in the case where the pump comprises at least two centrifugal impellers, driven and compressed again by the second centrifugal wheel.

The fluid thus compressed is then collected at the outlet of the second centrifugal wheel by a diffuser, which slows down the fluid before feeding a toroidal delivery duct, or collector. Such a device is disclosed, for example, in French patent application No. FR 2772 843.

[0004] During engine operation, the casing of the turbopump is subjected to mechanical stresses which pass through these different parts. By physical principle, efforts take the most direct path through the structure.

According to the design of the system, the forces can pass through functional areas, that is to say areas on which the performance of the pump depends, for example the diffuser. Significant efforts can deform these areas, and adversely affect the performance of the turbopump. Excessive efforts can also call into question the mechanical integrity of these functional areas, which can lead to a risk of ruin of the engine, and therefore of the spacecraft. In addition, to allow the diffuser to withstand the stresses to which it is subjected, a turbopump designer can be led to increase the thicknesses of material in the blades of the diffuser, which can adversely affect the performance of the pump.

There is therefore a need for a device to overcome these drawbacks.

PRESENTATION OF THE INVENTION The present disclosure relates to a fluid transfer device comprising:

a pump configured to compress a fluid, the pump comprising a pump body and at least one impeller inside the pump body, arranged around a central axis, a diffuser for receiving and redirecting the fluid discharged by the impeller, and a fluid manifold arranged around the pump body and the diffuser and configured to collect the compressed fluid leaving the diffuser, in which, in a section passing through the central axis, the manifold has two ends each connected to the pump body, and between them, a central part having an internal surface of substantially oval shape, a first junction part and a second junction part, the first and second junction parts connecting the central part to the ends of the manifold , the central part and the junction parts having, between the ends, a capacity to deform such that, during nominal operation of the device, f, a maximum mechanical stress in the diffuser is less than a maximum mechanical stress in the manifold.

In general, the manifold has a shape of a torus surrounding the pump body. In a section passing through the central axis, the manifold has two ends each connected to the pump body. It is understood that the ends of the manifold are connected to the pump body in any section of the manifold, so that each end of the manifold is connected to the pump body along the circumference of the latter.

In this section, the central part of the manifold generally has substantially the shape of a circular arc, the first and second junction parts connecting the ends of this circular arc to the pump body.

The first and second junction parts are configured so that, during normal operation of the device, that is to say when the manifold is under pressure, the mechanical stresses in the manifold always remain greater than those in the diffuser. In other words, the manifold is configured so that the mechanical stresses are greater in the joining parts than in the diffuser.

This device therefore allows, relative to a device not having this configuration, to deflect the path through which pass the mechanical stresses, favoring a passage of these stresses in the collector, resulting in a deformation of the first and / or of the second junction part, and of the central part, so that the collector tends to flatten, rather than a deformation of the outlet section of the diffuser. Thus, during normal operation of such a device, in a turbopump for example, the mechanical stresses passing through the diffuser are limited, the design constraints relating to the diffuser are therefore lower, which allows on the one hand d '' optimize it and therefore improve the efficiency of the pump, and on the other hand to guarantee the mechanical integrity of the functional areas of the motor.

In some embodiments, an internal face and / or an external face of the first junction part and of the second junction part has a circumferential groove.

By "circumferential", it is understood that the groove formed on the internal face and / or an external face of the first junction part and the second junction part of the collector extends along the latter, following the circumference of the pump body. In addition, the internal face of the junction parts designates the face in contact with the fluid flowing in the collector, and the external face designates the face opposite to said internal face, that is to say the face directed towards the outside the device.

Conventionally, the ends of the manifold have a very large thickness, which is traditionally provided to stiffen the manifold. Contrary to this old concept, the present invention can provide in particular the presence of groove (s) in the vicinity of at least one of the ends of the collector, which considerably reduces or reduces the thickness of the collector in the vicinity of its ends. The presence of such a groove makes it possible to locally weaken the resistance to deformation of the wall of the collector, thereby facilitating the deformation of the first junction part and of the second junction part during normal operation of the device.

In some embodiments, the ends of the manifold are connected to the pump body at a distance from the outlet of the diffuser.

The outlet of the diffuser is the opening through which the fluid enters the manifold, leaving the diffuser. By “remote”, it is understood that the ends of the manifold are not directly adjacent to the outlet section of the manifold, but are connected to the pump body so as to be offset with respect to this section. This offset generates a modification of the shape of the manifold compared to a configuration in which the ends of the manifold are directly adjacent to the outlet section of the diffuser, without any offset. More precisely, this offset makes it possible to create a groove, or a cavity at the level of these ends. The first and second junction parts are thus formed.

In some embodiments, at least one joining part has both an internal groove on the internal face of the joining part, and an external groove on the external face of the joining part, and, in one section passing through the central axis, the internal groove and the external groove are offset with respect to each other.

The grooves on the inner and outer faces are, for example offset relative to each other so as to form, in a section passing through the central axis, substantially the shape of an 'S' or d 'a chicane. This configuration makes it possible to promote the flattening of the collector when the latter is subjected to mechanical stresses, during normal operation of the device.

The deformable parts can be produced overall in two ways: by the choice of materials, and / or by the shape of the collector, in axial section.

In some embodiments, the first and second junction parts include a material whose elastic modulus is lower than that of the central part.

In certain embodiments, the elastic modulus, or Young's modulus, of the first and second junction parts is between 90,000 Mpa and 110,000 Mpa, preferably between 95,000 Mpa and 105,000 Mpa, preferably still equal to 100,000 Mpa, and the elastic modulus, or Young's modulus, of the central part is between 190,000 Mpa and 210,000 Mpa, preferably between 195,000 Mpa and 205,000 Mpa, preferably still equal to 200,000 Mpa.

Consequently, during normal operation of the device, the junction parts are more easily deformed than the central part, under the effect of mechanical stresses, causing an overall deformation of the collector. This deformation makes it possible to favor the passage of mechanical stresses in the collector, rather than in the diffuser.

In some embodiments, at least one of the junction parts has a projecting part inside the manifold, the projecting part being oriented towards an outlet section of the diffuser.

In some embodiments, a surface of the protruding portions disposed on the side of the interior of the manifold is oriented so as to channel the fluid into the manifold.

The projecting part is formed on the internal face of the collector. Furthermore, the projecting part is oriented towards an outlet section of the diffuser, so as to channel the fluid in the manifold. In other words, when the internal face of the central part substantially forms an arc of a circle, the projecting part is formed in the extension of this arc of circle, so that the surface of the projecting part disposed of the internal side of the collector is continuous with the internal face of the central part. The presence of these projections makes it possible to limit the turbulence likely to occur in the grooves arranged on the internal face of the junction parts. Indeed, in the absence of these projections, these grooves generate pressure losses in the flow of the fluid in the manifold. The presence of these projections therefore makes it possible to limit these pressure drops, thereby improving the efficiency of the pump.

In some embodiments, the internal groove of the first junction part extends between a first end of the manifold and the base of a first projecting part, and the internal groove of the second junction part s extends between a second end of the manifold and the base of a second projecting part.

The groove on the internal face of the first junction part, for example, can be defined between the end of the manifold connected to the pump body at a distance from the outlet section of the diffuser, and the projecting part.

In some embodiments, the manifold has two parts welded to each other, namely a radially external part, and a fixing part disposed between the pump body and the radially external part.

The presence of a weld between these two parts is possible due to the presence of the groove. Indeed, in the absence of a groove in the junction parts, in other words, at the level of the part located between the central part and the ends of the collector, the thickness of the wall of the collector is greater than in the presence of a groove, preventing a weld between two parts. In this case, the collector must be formed in one and the same block. On the other hand, the thickness of the wall of the collector being smaller due to the presence of the groove, it is possible to produce the collector in two parts, and to weld these two parts together. This simplifies the manufacturing process of the device.

The present disclosure also relates to a turbopump, in particular space, comprising a device according to any one of the preceding embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and its advantages will be better understood on reading the detailed description given below of various embodiments of the invention given by way of nonlimiting examples. This description refers to the pages of attached figures, on which:

- Figure 1 shows a view in axial half-section of an example of a centrifugal turbopump equipped with a fluid transfer device according to the prior art;

- Figure 2A schematically shows the diffuser and the manifold of the turbopump of Figure 1, and Figures 2B and 2C schematically show a diffuser and a manifold of a turbopump according to the present description;

- Figure 3A shows a view in axial half-section of an example of fluid transfer device according to the prior art, and Figure 3B shows a view in axial half-section of an example of fluid transfer device according to this presentation.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENT [0032] FIG. 1 represents a multi-stage turbopump 10 close to certain turbopumps equipping the cryogenic rocket motors designated by the name Vulcain (registered trademark) and serving to supply these engines with liquid hydrogen high pressure. The turbopump 10 comprises a two-stage centrifugal pump 16, and a turbine 18 which rotates the rotor of the pump 16 about an axis A.

Inside a casing, or pump body 12, the rotor of the pump 16 comprises a first centrifugal wheel 20 provided with blades 22, a second centrifugal wheel 30 provided with blades 32, an inductor 24 and a connecting piece 49.

The inductor 24, which gives good suction characteristics and allows a high speed of rotation, is placed at the inlet of the pump 16 downstream of the intake duct of the pump 16 (not shown) in working fluid. The connecting piece 49 secures the rotation 30 of the wheel 30 with the rotor of the turbine 18.

The stacking and axial clamping of the inductor 24, the wheels 20 and 30, and the connecting piece 49 are provided by a tie rod or central shaft 40 of the pump 16.

The stator of the pump 16 comprises the pump body 12 and, inside thereof, a set of fluid return channels 50. These capture and slow down the fluid discharged by the wheel 20 and direct it towards the entrance of wheel 30.

In the pump 16, the working fluid is sucked at the level of the inductor 24; it is driven and compressed by the first impeller 20; it is collected at the outlet of the wheel 20 by the fluid return channels 50. The working fluid is then entrained and compressed again by the second paddle wheel 30.

The fluid thus compressed is then collected at the outlet of the wheel 30 by a diffuser 34, which slows down the fluid before supplying the delivery toric conduit, or manifold 36.

During normal operation of the turbopump, the structure thereof is subjected to stresses such as external stresses coming from the pump, stresses caused by the rotor 16, stresses linked to the pressure, to the temperature, etc. The forces generated by these constraints can pass through functional areas of the turbopump 10, in particular the diffuser 34. The efficiency of the pump 16 depends in particular on this diffuser 34. In the event of significant deformations of the latter, the efficiency of the pump 16 can be decreased.

Figure 2A schematically illustrates the manifold 36 of Figure 1, including the path of forces (solid line) in the structure of the device. The forces pass in particular along the pump body 12, passing through the diffuser 34.

Figure 2B schematically illustrates a manifold 36 having junction parts according to the present description. More specifically, the manifold 36 comprises a first junction part 361, a second junction part 362, and a central part 363. The first junction part 361 and the second junction part 362 each have one end connected to the pump body 12 , for example by welding, and one end connected to the central part 363.

According to this embodiment, each of the first and second junction parts has an internal groove 361a, 362a respectively, and an external groove 361b, 362b respectively. The internal grooves are zones hollowed out on the internal face of the manifold 36, inside which the fluid coming from the diffuser 34 circulates. The external grooves are zones hollowed out on the external face of the manifold 36.

During normal operation of the pump, when the device is subjected to considerable pressures due to the passage of the fluid, the presence of these grooves promotes the deformation of the manifold 36 under the effect of these constraints. Fig 2C illustrates the deformation of the manifold 36 under the effect of stresses, the latter tending to flatten the manifold 36, the flexion of which is favored at the level of the grooves. This deformation of the manifold 36 has the effect of deflecting the path of the forces passing through the pump body, these forces favoring a passage through the wall of the manifold 36, rather than through the diffuser 34.

FIG. 3B shows a view in axial half-section of an example of a centrifugal turbopump equipped with a fluid transfer device according to the invention. The first joining part 361 has an internal groove 361a and an external groove 361b, and the first joining part 362 has an internal groove 362a and an external groove 362b. The first junction part 361 has a first projecting part 364 inside the manifold 36, the first projecting part 364 being oriented towards the outlet section of the diffuser 34. The second junction part 362 has a second projecting part 365 inside the manifold 36, the second projecting part 365 being oriented towards the outlet section of the diffuser 34.

The protruding parts 364, 365 are formed on the internal face of the collector 36, in the extension of the central part 363, so that the internal face of the collector 36 according to the present description retains substantially the same profile as the internal face of a collector according to the prior art (cf. FIG. 3A). Thus, by their shape, their position and their orientation, these projecting parts 364, 365 are configured to guide the fluid coming from the diffuser 34, in the manifold 36, while minimizing the pressure losses linked to the flow of this fluid. .

According to this embodiment, the collector 36 can be manufactured in two parts, connected together by a weld. This welding can be carried out at the junction parts, between the ends of the manifold 36 and the projecting parts 364, 365. These welds are possible thanks to the presence of the internal grooves 361a, 362a, implying a smaller thickness of the manifold 36 in the junction parts 361, 362, compared to a configuration in which the manifold does not have a groove (cf. FIG. 3A).

According to a second embodiment of the invention, the joining parts 361, 362 do not have a groove, but the material constituting the first and second joining parts 361,

362 has a modulus of elasticity, or Young's modulus, lower than that of the central part. The effect obtained is the same as for the first embodiment, namely that under the effect of external stresses, the collector 36 will tend to deform while flattening, thus making it possible to deflect the forces passing through the pump body 12, favoring a passage through the wall of the manifold 36, rather than through the diffuser

34. Alternatively, the first and second junction parts may comprise a material having anisotropic properties, having a modulus of elasticity, or Young's modulus, weaker in a direction favoring the deformation of the collector under the effect of external constraints.

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

It is also obvious that all the characteristics described with reference to a method can be transposed, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims (9)

1. Fluid transfer device comprising: a pump (16) configured to compress a fluid, the pump (16) comprising a pump body (12) and at least one impeller (30) inside the pump body (12), arranged around a central axis, a diffuser (34) for receiving and redirecting the fluid discharged by the impeller (30), and a fluid manifold (36) arranged around the pump body (12) and the diffuser (34) and configured for collecting the compressed fluid leaving the diffuser (34), in which, in a section passing through the central axis, the manifold (36) has two ends each connected to the pump body (12), and between them, a central part (363) having an internal surface of substantially oval shape, a first junction part (361) and a second junction part (362), the first and second junction parts (361, 362) connecting the central part ( 363) at the ends of the manifold (36), the central part (363) and the joining parts (361, 362) pr having, between the ends, a capacity to deform such that, during nominal operation of the device, a maximum mechanical stress in the diffuser (34) is less than a maximum mechanical stress in the manifold (36). 2. Device according to claim 1, in which an internal face and / or an external face of the first joining part (361) and the second joining part (362) has a circumferential groove (361a, 361b, 362a, 362b ). 3. Device according to claim 2, in which at least one joining part (361, 362) has both an internal groove (361a, 362a) on the internal face of the joining part (361, 362), and a external groove (361b, 362b) on the external face of the junction part (361, 362), and, in a section passing through the central axis, the internal groove (361a, 362a) and the external groove (361b, 362b ) are offset from each other. 4. Device according to any one of claims 1 to 3, wherein the first and second junction parts (361, 362) comprise a material whose elastic modulus is less than that of the central part (363). 5. Device according to any one of claims 1 to 4, wherein at least one of the joining parts (361, 362) has a projecting part (364, 365) inside the manifold (36), the part projecting (364, 365) being oriented towards an outlet section of the diffuser (34). 6. Device according to claim 5, in which a surface of the projecting parts (364, 365) arranged on the side of the interior of the collector (36) is oriented so as to channel the fluid in the collector (36). 7. Device according to claim 5 or 6, wherein the internal groove (361a) of the first joining part (361) extends between a first end of the manifold (36) and the base of a first projecting part ( 364), and the internal groove (362a) of the second joining part (362) extends between a second end of the manifold (36) and the base of a second projecting part (365). 8. Device according to any one of claims 1 to 7, in which the collector (36) comprises two parts welded to each other, namely a radially external part, and a fixing part arranged between the body of pump and the radially external part. 9. Turbopump, in particular space, comprising a device according to any one of the preceding claims.