RU2481489C1 - Turbo-pump unit of rocket engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: in a turbopump unit containing a turbine and oxidiser and fuel pumps installed coaxially to it and each containing one centrifugal impeller and a screw, external and internal shafts, a turbine wheel is installed on the internal shaft. The oxidiser pump is two-stage; both stages are of centrifugal screw type, and between the screw and the impeller of the second stage of the pump there installed is a hydraulic turbine fixed on the external shaft that passes inside the centrifugal impeller of the first stage and is connected to the screw of the first stage of the pump; the screw has external bandage ring rigidly attached to the centrifugal impeller of the second stage of the first pump; the first impeller of the pump is connected to the internal shaft through a magnetic coupling, between oxidiser and fuel pumps there is a reduction gear, in the housing of which an additional fuel pump is installed; internal shafts of oxidiser and fuel pumps are connected to a spring; the shaft of the additional fuel pump is connected to the internal shaft of the fuel pump through the reduction gear.

EFFECT: improvement of cavitation properties of pumps with minimum weight of a turbopump unit and unloading of axial forces of internal and external shafts.

3 cl, 7 dwg

Description

The invention relates to pump engineering and can be used for pumping rocket fuel components, both high-boiling and cryogenic, in turbopump units (TNA) of liquid-propellant rocket engines.

Known screw centrifugal pump according to the patent of the Russian Federation for invention No. 2094660, comprising a detachable body, centrifugal impellers (impellers), auger, shaft and support units in the form of sliding and rolling bearings. The pump has poor cavitation properties.

Known screw centrifugal pump according to the patent of the Russian Federation No. 2106534, 03/10/1998. This centrifugal screw pump comprises a housing, an impeller and an auger mounted on a shaft. The screw improves the cavitation properties of the pump, as it has better cavitation properties than a centrifugal impeller. The screw provides an increase in the cavitation properties of the pump, but it is mechanically connected to the impeller of the pump and has the same angular rotation speed with it. This does not allow the pump to be operated at very high speeds, for example 40-100 thousand rpm, therefore, such pumps are not currently used.

Known turbopump assembly according to the patent of the Russian Federation No. 2300021, which contains a multistage centrifugal pump and a single-stage turbine. To reduce the dimensions, the pump and turbine are designed for the maximum permissible strength rotational speed of the TNA rotor. At the same time, the cavitational qualities of the pump are deteriorating.

Known turbopump unit (TNA) according to the patent of the Russian Federation for invention No. 2083881. This TNA contains a multistage centrifugal pump and a two-stage turbine connected by a shaft mounted on bearings in the housings.

Disadvantages: poor cavitation qualities of a centrifugal pump, especially when it is operating at high speeds, as well as poor unloading of axial forces. When gas is supplied to the turbine from the side opposite to the pump inlet, the axial forces acting on the turbine rotor and the pump rotor are directed in one direction, i.e. add up to the absolute value.

A multi-stage turbopump assembly is known, comprising a housing with a front cover and a suction nozzle, two coaxially mounted shafts with annular cavity between them, mounted on the bearings, each impeller mounted on it (UK patent No. 775547, cl. 110 (1), 1953 )

A disadvantage of the known device is the low reliability, increased dimensions and weight. The absence of a means to reduce shaft vibrations arising during operation due to the presence of structural vibrations and pulsations at rest of the pumped component leads to a decrease in the reliability of the shafts in operation. To increase the strength of the shafts, it is necessary to increase their diametrical dimensions and the thickness of the cylindrical part, especially the outer shaft. In this case, the diametrical dimensions of the rotor parts mounted on the shafts grow, and with them the diametrical dimensions of the housings. This leads to an increase in the size and weight of the units.

Closest to the invention is a turbopump unit of a rocket engine according to the patent of the Russian Federation for invention No. 2232300, 07/10/2004. This TNA contains a turbine and two pumps for pumping rocket fuel components: an oxidizer and fuel. The pumps are made by centrifugal augers and contain centrifugal impellers and augers installed in front of them.

The disadvantages of the known TNA are the relatively poor cavitation properties of the pumps and their large dimensions, due to the fact that the first stage of the first pump (from the turbine), driven by a hydraulic turbine, has a low rotational speed and, as a result, large dimensions and low pressure. In addition, bypassing rocket fuel components to the pumps inlet adversely affects their cavitation properties. Unloading of axial forces for two shafts has not been worked out: external and internal for oxidizer pumps and fuel.

The objectives of the invention are to improve the cavitation properties of the pumps while ensuring the minimum weight of the turbopump unit and ensuring the unloading of the axial forces of the internal and external shafts.

The solution of these problems was achieved in a turbopump unit of a rocket engine containing a turbine and oxidizer and fuel pumps mounted coaxially with it, containing, in turn, each at least one centrifugal impeller and at least one screw, external and internal shafts, the turbine impeller is mounted on the inner shaft, the oxidizer pump is two-stage, and both stages are screw centrifugal, and hydrot is installed between the screw and the impeller of the second stage of the two-stage pump a rotor mounted on an external shaft that extends inside the centrifugal impeller of the first stage and is connected to the screw of the first stage of the two-stage pump, the screw has an external retaining ring rigidly connected to the centrifugal impeller of the second stage of the first pump, while the first impeller of the two-stage pump is connected with an internal shaft through a magnetic coupling, characterized in that a gearbox is made between the oxidizer and fuel pumps, in the housing of which an additional fuel pump is installed, e the shafts of the oxidizer and fuel pumps are connected by a spring; the shaft of the additional fuel pump is connected to the internal shaft of the fuel pump through a gearbox. The screw of the second pump can be rigidly mounted on the inner shaft. The screw of the second pump can be connected to the internal shaft through a magnetic coupling.

The invention is illustrated by drawings of figures 1-7, where:

figure 1 shows a General longitudinal section of a turbopump unit;

figure 2 is a longitudinal section of the oxidizer pump

figure 3 - design of the first stage of the first pump;

figure 4 - design of the turbine and the second stage of the first pump;

figure 5 - design of the second pump,

figure 6 - design of an additional fuel pump, type A,

Fig.7 is a section bb in Fig.3.

The turbopump assembly (Figs. 1-7) comprises a turbine 1, an oxidizer pump 2, and a fuel pump 3 mounted coaxially.

At least one of the pumps 2 or 3 is made two-stage and contains, for example, an oxidizer pump, the first and second stages 4 and 5, respectively. The oxidizer pump 2 contains two shafts: inner 6 and outer 7 installed in the bearings 8. Between the shafts 6 and 7, a radial clearance “C” is made for the passage of a portion of the pumped product (rocket fuel component) intended for lubricating the bearings 8. Hole “D” communicates with a clearance "C" between the shafts 6 and 7. The oxidizer and fuel pumps 2 and 3 are made centrifugal, or rather screw centrifugal.

The first stage 4 of the two-stage oxidizer pump 2 (Fig. 2) contains a centrifugal impeller 9 with a hub 10 mounted with the possibility of circumferential slip on the external shaft 7. The screw 11 is also included in the first stage 4, which is rigidly connected to the external shaft 7. The centrifugal working the wheel 9 is installed in the housing 12. To the housing 12 is connected the inlet pipe 13 with the inlet cavity 14. In the inlet pipe 13 holes are made connecting the cavity 14 and the gap. The first centrifugal impeller 9 is connected to the inner shaft 6 through a magnetic coupling 15.

The second stage 5 of the first pump 2 (Fig. 3) contains a second centrifugal impeller 16 rigidly mounted on the inner shaft 6 and having a hub 17. The second centrifugal impeller 16 is installed in the housing 18. An adapter housing 19 is docked to the housing 18, while the outlet of the first stage 4 of the pump 2 is connected to the cavity inside the housing 19, made at the entrance to the second stage 5 of the pump 2. To the housing 18 is connected the outlet pipe 20 with the output cavity 21. The second stage 5 contains a screw 22 having an external retaining ring 23, rigidly connected left with a centrifugal impeller 16. Between the screw 22 and the impeller 16 is installed a hydraulic turbine 24 (more precisely, its impeller), rigidly connected to the external shaft 7.

The fuel pump 3 (Fig. 1) is also made two-stage and contains two stages 25 and 26. The first stage 25 contains a first centrifugal impeller 27 with a hub 28 mounted on the outer shaft 29 and rigidly connected to it, for example, by means of dowels or splines. The first stage 27 also contains a screw 30, while the screw 30 is rigidly mounted on the external shaft 29. A centrifugal impeller 27 and a screw 30 are installed in the housing 31. An inlet pipe 32 with a cavity 33 is docked to the housing 31. The centrifugal impeller 34 of the second stage 26 mounted on the inner shaft 35, and both are installed in the housing 36. In front of the centrifugal impeller 34, a screw 37 is installed. At the same time, the output housing 38 can be made with the housing 36.

An opening 39 is formed in the output housing 38.

The inner shafts 6 and 35 are connected by a spring 40. A gear 41 connects the outer shaft 29 to the internal shaft 34 of the fuel pump 3. The gear 41 contains a housing 42. An additional fuel pump 43 is made in the housing 42, comprising a centrifugal impeller 44 with a shaft 45 mounted on two bearings 47 and 48. A driven gear connected to the gear 41 is installed on the shaft 45. The shaft 45 and the centrifugal impeller 44 are connected by a bolt 49. A sleeve 50 is installed between the bearings 47 and 48 with a baffle 51 sealed on the shaft 45 by a seal 52. For lubricating the bearings 47 and 48, and the reducer 41 uses high-pressure fuel taken from the cavity 38. For strict dosing of the flow of this fuel in the partition 51, metering nozzles 53 are made (Fig. 6).

The turbine 1 can be made single-stage or multi-stage. The following is an example of a TNA with a single-stage turbine 1 (Fig. 4). The turbine 1 comprises an impeller 54 fixed on the internal shaft 6 by the working blades 55. A nozzle apparatus 56 is fixed in front of the working blades 55. The turbine 1 has a housing 57 to which an inlet pipe 58 with a cavity 59 and an outlet pipe 60 with a cavity 61 are connected.

The oxidizer and fuel pumps 2 and 3 have front and rear seals, respectively 62 and 63, on all centrifugal impellers. Unloading cavities 64 are formed under the rear seals 63. The shafts 6 and 7 are sealed relative to the bearings 8 by seals 65. Friction rings 66 are installed between the screws and centrifugal impellers rotating at different speeds.

The design of the magnetic coupling 15 is shown in Fig.7. The magnetic clutch 15 comprises a leading and a driven half-coupling, 67 and 68, respectively, with permanent magnets 69 fixed to them. In this case, the function of the driving coupling half 67 is performed by a part of the external shaft 7, and the function of the driven coupling half 68 is by the hub 10 of the centrifugal impeller 9 with permanent magnets 69. The portion of the external shaft 7 between the permanent magnets 69 or the entire shaft 7 must be made of magnetically permeable material, for example non-magnetic steel, to ensure the transfer of magnetic flux. Modern technologies make it possible, using small-sized permanent magnets 69, to transfer powers of 10 - 50 MW, which is enough to drive the pumps of the most powerful LRE. The design of the magnetic coupling 70 of the fuel pump 3 is similar to the design of the magnetic coupling 15. The output of the fuel pump 3 is connected to the inlet of the additional fuel pump 43 by a pipe 71 (Figs. 1 and 3).

The outer shaft 29 is sealed on the inlet side of the fuel pump by a seal 72. Between the bearing 8 and the seal 72, a radial hole 73 is made in the outer shaft (Fig. 1).

TNA WORK

When starting the turbopump assembly, gas is supplied through the inlet pipe 58 into the cavity 59 of the turbine 1 and passes through the nozzle unit 56 and the working blades 55, the inner shaft 6 of the oxidizer pump 2 and the inner shaft 45 of the fuel pump 3 are untwisted. The centrifugal impeller 16 and the centrifugal are untwisted the impeller 34. The pressure of the oxidizing agent in the cavity 21 increases. The oxidizing stream spins a hydraulic turbine 24, which spins the outer shaft 7, which drives the screw 11. The centrifugal impeller 9 drives the inner shaft 6 through the magnetic coupling 15. The screw 11 increases the pressure at the inlet of the centrifugal impeller 9, thereby preventing cavitation at its entrance. Cavitational properties of screws are always better than centrifugal impellers. To significantly improve the cavitation properties of the screw 11, it is designed to operate at a rotation speed n2 less than the rotational speed n1 of the centrifugal impeller 9, 2 to 3 times, which is technically uncomplicated by designing a low-power turbine 24, for example, by reducing its dimensions. This will also favorably affect the weight characteristics of the TNA. In this case, the centrifugal impeller 9 of the first stage 4 of the first pump 2 rotates at the same angular speed as the impeller 54 of the turbine 1, i.e. with speed n1. This allows you to significantly reduce the diametrical dimensions of this centrifugal wheel and get more pressure on it than in the same centrifugal impeller of the prototype. In addition, to drive a centrifugal impeller and auger using a low-power hydraulic turbine, as implemented in the prototype, is very problematic.

The outer shaft 29 is driven from the inner shaft 35 through a gearbox 41, which reduces its rotational speed by 2 to 3 times to improve the cavitation properties of the fuel pump 3. For this purpose, a seal 72 and a hole 73 are made, which significantly reduce the bypass of the heated fuel to the fuel pump inlet 3 (FIG. 1).

The application of the invention allows:

1. Significantly improve the cavitation properties of the oxidizer and fuel pumps and both stages of the two-stage (two-stage) pumps due to the use of augers at the inlet to all centrifugal impellers of the pumps and a decrease in the rotational speeds of the augers due to a separate drive in a two-shaft circuit and bypass of the heated components not to the entrances to pumps, and after them.

2. To provide a very high pressure for part of the flow rate of one of the components of rocket fuel (fuel) using an additional pump having a high speed due to communication with the fuel shaft through a multiplier that increases the speed of rotation.

3. Ensure reliable cooling of all bearings, the multiplier and other contact parts of the TNA.

4. To ensure the unloading of the axial forces of the shafts due to the coaxial arrangement of the turbine and pumps, the use of rear seals forming the discharge cavities.

5. Design a turbopump unit of very high power by increasing the speed of the centrifugal impellers of both pumps to the maximum permissible strength.

6. To prevent disruption of the flow of pumped components of rocket fuel in the pumps due to cavitation at their inlets.

7. To create a turbopump unit with minimum weight and dimensions with a large head and productivity due to the use of maximum angular velocities of the centrifugal impellers of both pumps, the use of a multi-stage circuit of one or both pumps and the use of an additional fuel pump drive through a gear that increases its speed ..

Claims (3)

1. The turbopump unit of a rocket engine containing a turbine and oxidizer and fuel pumps mounted coaxially with it, comprising, in turn, each at least one centrifugal impeller and at least one screw, external and internal shafts, working the turbine wheel is installed on the inner shaft, the oxidizer pump is made of two stages, both stages are screw centrifugal, and a turbine mounted on the outer shaft is installed between the screw and the impeller of the second stage of the two-stage pump, which passes inside the centrifugal impeller of the first stage and is connected to the screw of the first stage of the two-stage pump, the screw has an external retaining ring rigidly connected to the centrifugal impeller of the second stage of the first pump, while the first impeller of the two-stage pump is connected to the internal shaft through a magnetic coupling, characterized in that a gearbox is made between the oxidizer and fuel pumps, in the housing of which an additional fuel pump is installed, the internal shafts of the oxidizer and fuel pumps connected by a spring, with the internal shaft of the fuel pump through the gearbox connected to the shaft of the additional fuel pump. 2. The turbopump unit of a rocket engine according to claim 1, characterized in that the screw of the second pump is rigidly mounted on the inner shaft. 3. The turbopump assembly according to claim 1, characterized in that the screw of the second pump is connected to the internal shaft through a magnetic coupling.

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