RU2459118C1 - Turbo-pump unit - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: unit contains pumps of oxidiser and fuel with spline joined shafts, turbine wheel is fastened on one of shafts. Unit contains dummy piston of automatic unloading machine, the piston is combined with the main propeller disk of one of pumps. Unloading machine is restricted by radial seal in peripheral part of the main disk and by control axial slot near propeller hub. Ball bearing of this pump is designed with outer ring installed in housing with axial gap, ball bearing of the second pump is designed with axial stop located in housing with gap along butt end of ball bearing outer ring. Shaft of one pump with backing butt-end rest on backing butt-end of shaft of the second pump. Gaps along butt-ends of axial stop of outer ring of ball bearing of pump without unloading machine are designed larger than corresponding axial gaps along butt-ends of outer ring of ball bearing of pump with unloading machine.

EFFECT: improving efficiency factor of turbo-pump unit and enhancing pump anticavitation properties.

3 cl, 3 dwg

Description

The invention relates to the field of mechanical engineering, namely to the field of blade machines, and can be used in the field of rocketry, in turbopump units (TNA) of liquid rocket engines (LRE) and nuclear rocket engines (NRE).

When creating the ТНА LRE, one of the key points in creating the unit is to ensure that the rotor bearings are unloaded from the action of axial forces, since in the pumps and turbines of the ТНА axial forces can reach several tens of kN. For unloading from axial forces, automatic unloading devices are used. The design of the axial unloading devices of the rotors may be different. The most commonly used design is an automatic unloading device with an unloading piston combined with the main impeller disk and a limited radial unregulated seal in the peripheral part of the impeller and automatically adjusting the axial gap at the impeller hub. The cavity after the regulatory axial slit is connected to the inlet cavity of the impeller by discharge openings made in the hub of the main disk of the impeller.

A known design of a turbopump assembly, consisting of two pumps - an oxidizer and fuel, whose shafts are connected by a splined spring or coupling, and a turbine mounted on the shaft of one of the pumps, has an automatic unloading device in each pump (Dmitrenko A.I. Development of the design of the turbopump units LRE developed at KBHA // Scientific and Technical Anniversary Collection. Design Bureau of Chemical Automation - Voronezh Institute of Applied Physics, 2001. - P.308-314 - prototype).

The specified design of the turbopump unit with automatic unloading devices in each pump is typical for TNA LPRE with afterburning. The disadvantage of this design is the presence of increased leakage of the working fluid in the automatic unloading devices, which reduce the efficiency of each pump, which leads to a decrease in the total efficiency of the turbopump unit. In addition, leaks of the working fluid flowing through the discharge openings into the inlet cavity of the impeller impair the anti-cavitation qualities of the pump.

The present invention is directed to increasing the efficiency of a turbopump unit and improving the anti-cavitation qualities of a pump.

The technical effect is achieved by the fact that in a turbopump assembly containing oxidizer and fuel pumps with shafts connected to the shafts and pump impellers mounted on the shafts, a turbine wheel mounted on one of the shafts, a discharge piston of an automatic unloading device combined with the main disk of the impeller of one of the pumps limited by a radial seal in the peripheral part of the main disk and a regulating axial gap at the impeller hub, the ball bearing of this pump with an outer ring mounted in a housing with an axial clearance, a ball bearing of a second pump with an axial stop located in a housing with a clearance at the end of the outer ring of a ball bearing, according to the invention, the shaft of one pump is supported by the supporting end on the supporting end of the shaft of the second pump, while the gaps are on the ends of the axial stop the outer ring of the ball bearing of the pump without automatic unloading device made more than the corresponding axial clearance at the ends of the outer ring of the ball bearing of the pump with automatic azgruzochnym device. Between the supporting ends of the shafts, a spline spring can be installed. To provide additional pressure on the shaft of the shaft ends, the outer rings of ball bearings, limiting the axial movement of the pump rotors, rely on elastic rings.

Figure 1 shows a General view, figure 2, 3 are variants of the proposed turbopump, where:

1 - oxidizer pump;

2 - fuel pump, elastic element;

3 - oxidizer pump shaft;

4 - a shaft of the fuel pump;

5 - spline connection between the shafts;

6 - impeller of the oxidizer pump;

7 - impeller of the fuel pump;

8 - turbine wheel;

9 - the main disk of the impeller of the fuel pump;

10 - discharge cavity of an automatic discharge device;

11 - radial seal in the peripheral part of the main disk;

12 - regulating axial gap of the automatic unloading device;

13 - discharge openings in the main disk of the impeller;

14, 15 - ball bearing;

16, 17 - the outer ring of the ball bearing;

18, 19 - front impeller seal;

20, 22 - contact end face of the spring;

21 - spring;

23, 26 - spring;

24, 25 - sleeve.

The turbopump assembly (Fig. 1) consists of an oxidizer pump 1, a fuel pump 2, and a turbine 8 mounted on the shaft of one of the pumps. Impellers 6 and 7 are installed on the pump shafts. From the entrance to the impellers of the pumps, the high-pressure cavities are separated from the low-pressure cavities by the front seals 18 and 19. The torque from the oxidizer pump shaft 3 to the fuel pump shaft 4 is transmitted using a spline connection, for example a spline connection couplings 5, while the pump shafts are supported by each other at the supporting ends 20. Instead of a spline coupling, a spline spring 21 can be used to transmit torque (Fig. 2). In this case, there are two supporting ends 22 - between the pump shafts and the spring. An automatic unloading device is made on the shaft of the fuel pump, the unloading piston of which is combined with the main impeller disk 9, the unloading cavity 10 of which is limited by a radial seal in the peripheral part of the main disk 11 and the regulating axial slot 12. The seal 11 separates the unloading cavity 10 from the high-pressure cavity, and axial slit 12 - from the drain cavity connected by discharge holes in the main impeller disk 13 to the pump inlet (low pressure cavity). The ball bearing of the oxidizer pump, limiting the axial movement of the rotor, is installed in the housing with gaps δ ₁ and δ ₂ at the ends of the outer ring. The ball bearing of the fuel pump, limiting the axial movement of the rotor, is installed in the housing with gaps δ ₃ and δ ₄ at the ends of the outer ring. When assembling the unit, the conditions δ ₁ > δ ₃ and δ ₂ > δ ₄ must be satisfied, providing the automatic unloading device with the ability to work for axial unloading of the rotors of both pumps. In the embodiment shown in FIG. 3, axial springs 23, 26 are installed in the rotor bearings, the force of which is aimed at creating contact between the shafts before starting the turbopump assembly, the springs are based on bushings 24, 25, which can serve as limiters of axial movement of the pump rotors. At the same time, at the ends of the outer ring of the ball bearing of the oxidizer pump, which limits the axial movement of the rotor, gaps δ ₅ and δ _{6 are made} . At the ends of the outer ring of the ball bearing of the fuel pump, limiting the axial movement of the rotor, clearances δ ₇ and δ _{8 are made} . When assembling the unit with springs in the supports, the conditions δ ₅ > δ ₇ and δ ₆ > δ ₈ must be satisfied, which ensure that the automatic unloading device can operate for axial unloading of the rotors of both pumps. In addition, the installation of springs allows you to eliminate the gaps in ball bearings and increase their durability.

Before the start of the operation of the turbopump assembly, made according to figure 1, the rotors of the pumps can be in an arbitrary position without stopping at the end of the shafts or springs. When the unit starts to work due to the choice of rotor seal diameters, elimination of the rear impeller seal of one of the pumps and the automatic unloading device of the rotor of one of the pumps, the rotors are displaced towards each other, while during operation there is constant contact between the shafts directly or through a spline spring . Compensation of unloaded axial forces on the rotors is carried out by one automatic unloading device. Conditions δ ₁ > δ ₃ and δ ₂ > δ ₄ must be maintained at all operating modes, including taking into account force and temperature deformations of the structure. During the operation of the automatic discharge device, component leakage from the discharge cavity through the discharge openings in the main impeller disk enters the inlet part of the impeller, reducing the energy and cavitation characteristics of the pump, especially on cryogenic components (the stream after the discharge openings has a higher temperature, falling into the main colder flow, it does not have time to mix with it, as a result, the local temperature of the working fluid rises, which causes local increased temperature of saturated vapors and early nucleation of a cavitation cavity). Since in the proposed turbopump assembly the automatic device for axial unloading of the rotor is made only in one of the pumps, the efficiency and cavitation characteristics of the second pump will improve, which will lead to an increase in the overall efficiency of the turbopump.

In the turbopump assembly according to FIG. 2, to minimize the axial dimensions of the unit, to minimize the mutual influence of the pump rotors on each other, a splined spring is installed between the pump shafts, which serves to transmit torque from one shaft to another.

In the turbopump assembly made according to Fig. 3, in order to ensure contact between the pump shafts in all operating modes, including start and stop modes, in which hydraulic forces are insufficient for mutual pressing of the rotors, axial springs are installed in the supports, the force of which is directed towards each other . The springs can be supported by bushings, which can be used as limiters for the axial movement of the rotor. The sleeve and spring can be made as a single part. The conditions δ ₅ > δ ₇ and δ ₆ > δ ₈ should be maintained at all operating conditions, including taking into account force and temperature deformations of the structure.

The use of the invention improves the efficiency of the turbopump unit, which includes two pumps and a turbine, due to the use of only one of the pumps automatic unloading device, carrying out axial unloading of the rotors of both pumps. Increasing the efficiency of TNA is achieved by reducing the leakage of the working fluid in the pump, in which the automatic unloading device of the rotor is excluded.

For a pump operating on oxygen, the exclusion of an automatic axial unloading device increases the reliability of the TNA by eliminating the potential for frictional contact of the rotor and stator elements of the axial control slit of the automatic unloading device that is prone to fire in oxygen. In addition, the elimination of leaks through the discharge holes in the inlet cavity of the impeller improves the anti-cavitation qualities of the pump.

During the operation of the turbopump unit, the values of the diameters of the seals in both pumps and the turbine are selected so as to ensure constant contact between the pump rotors at their ends due to the action of forces caused by pressure drops in the flow part of the pumps and turbine. The transmission of torque from one shaft to another is carried out using a spline connection. Splined connection can be performed both directly in the pump shafts, and with the use of a spline coupling or spline spring.

In order to ensure the operability of the turbopump assembly during start-up and shutdown, when the pressures in the cavities are low, the design of the pumps includes elastic elements on which the outer rings of bearings restrain the axial movement of the pump rotors. Elastic elements provide constant contact of the shaft end faces before the start of the TNA operation and in all modes of its operation, when the counter force is not provided by hydraulic forces.

A turbopump LRE unit created using the present invention has higher efficiency and reliability due to the exclusion of an automatic unloading device in one of the pumps. In addition to the turbopump units of the rocket engine, the invention can be used in general industrial units that use several pumps and require unloading of the rotors from the action of axial forces.

Claims (3)

1. Turbo-pumping engine rocket engine containing oxidizer and fuel pumps with shafts connected to the shafts and pump impellers mounted on the shafts, a turbine wheel mounted on one of the shafts, combined with the main impeller disk of one of the pumps, an unloading piston of an automatic unloading device limited by radial sealing in the peripheral part of the main disk and the regulating axial gap at the impeller hub, the ball bearing of this pump with an outer ring installed in the whisker with axial clearance, a ball bearing of the second pump with an axial stop located in the housing with a gap on the end face of the outer ring of the ball bearing, characterized in that the shaft of one pump rests on its bearing end face of the shaft of the second pump, while the gaps on the ends of the axial stop of the outer ring a ball bearing of a pump without an unloading piston is made larger than the corresponding axial clearances at the ends of the outer ring of a ball bearing of a pump containing an unloading piston. 2. The turbopump assembly according to claim 1, characterized in that a spline spring is installed between the supporting ends of the shafts. 3. The turbopump assembly according to claim 1, characterized in that the outer rings of ball bearings, limiting the axial movement of the pump rotors, rely on elastic rings.

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