RU2730566C1 - Lpre booster turbopump unit (embodiments) - Google Patents

Abstract

FIELD: rocket construction.

SUBSTANCE: invention relates to rocket engineering and can be used in liquid-propellant rocket engines (LPRE), primarily oxygen-methane and oxygen-hydrogen. Booster turbo-pump unit of LPRE comprising pump, turbine, turbine bearing, pump bearing, separation cavity between pump and turbine, limited on turbine side by shaft seal, turbine bearing is installed on the pump side behind the separator, according to the invention the separation cavity is located between the turbine bearing and the shaft seal, on the turbine side, in the separating cavity a discharge disc is installed, on outer diameter of which there is a seal, and separation cavity in peripheral part is connected by discharge channels with pump outlet.

EFFECT: invention ensures reduction of power losses for separation of pump and turbine, increase of power supply system efficiency, reduction of thermal deformations of impeller of the gas turbine, reduction of force acting on bearings from axial forces.

8 cl, 3 dwg

Description

The invention relates to the field of rocketry and can be used in liquid-propellant rocket engines (LRE), mainly oxygen-methane and oxygen-hydrogen.

In liquid-propellant rocket engines, booster turbopump units (BTNA) with an axial pump are widely used, the drive for which is a hydraulic or gas turbine, the impeller of which is located on the shaft. Due to their simple design, such BTNAs have high reliability. One of the problems of creating a BTNA is to ensure the unloading of bearings from the action of axial forces while maintaining the maximum efficiency and reliability of the unit. These problems are especially acute in the BTNA of liquid methane and liquid hydrogen of oxygen-methane and oxygen-hydrogen rocket engines, as well as BTNA of reusable engines, regardless of the fuel components used. When a booster turbopump unit with an axial pump is operating, an axial force acts on its axial wheel due to the pressure difference it creates. This axial force acts from the outlet to the inlet of the pump. The higher the pressure drop generated by the pump, the greater the amount of axial force acting on the axial impeller of the pump. The magnitude of this effort can be several thousand kilonewtons. Since in booster turbopump units, as a rule, turbines with a low pressure drop across the turbine wheel are used, the axial force acting on the rotor from the turbine side is small and cannot balance the axial force from the axial pump wheel.

Known is a device for separating the pump and turbine of a hydrogen booster turbopump unit of a liquid-propellant engine (Cosmonautics and rocketry, issue 16, TsNIIMash, 1999. Page 79. Fig. 6), containing a separation cavity between the pump and the turbine, limited from the pump side by a shaft seal, and from the side turbine wheels with a discharge disc with its seal. The working medium is supplied to the separating cavity from an external source. A turbine bearing is placed in the separation cavity between the shaft seal and the balance disc.

The disadvantages of this device are:

- to balance the axial force from the axial impeller of the pump, a large-diameter unloading disc installed in the separation cavity must be used;

- the diameter of the shaft seal is larger than the diameter of the shaft at the site of the turbine bearing, which also entails an increase in the diameter of the unloading disc;

- the increased diameter of the unloading disc leads to an increase in friction power losses associated with the rotation of the disc;

- the increased diameters of the shaft seals and the unloading disc cause increased power losses associated with leaks of the working medium from the separation cavity, the leaks in magnitude can be comparable to the flow rate of the working gas through the turbine;

- high-pressure hydrogen is supplied to the separation cavity between the pump and the turbine from the outlet of the hydrogen pump of the main turbopump unit, this hydrogen is in the gas phase, which deteriorates the cooling conditions for the turbine bearing;

- leakage of the liquid component from the separation cavity into the cavity of the BTNA turbine reduces its efficiency;

- the presence of an external supply path to the separating cavity and the bearing cavity of the BTNA turbine complicates the design of the engine, since it requires the inclusion of a separate line in the engine for supplying the high-pressure liquid component from the main turbo pump unit to the BTNA.

Known LPRE booster pump unit (RF Patent 2134821 C1. LPRE booster pump unit. Published on 08/20/1999), a separating seal in which is a combination of an impeller and a slotted seal, is installed between the turbine and the pump.

The disadvantages of this device are:

- the leakage of the liquid component from the separation cavity into the cavity of the BTNA turbine reduces both its efficiency and the efficiency of the BTNA;

- the force on the bearings from the action of axial forces consists of the force acting on the impeller of the pump and the impeller, there is no possibility of compensating the force acting on the bearings.

Known is a device for separating a pump and a turbine BTNA LRE, which contains a pump, a turbine, a separating cavity between the pump and the turbine, limited from the pump side by a shaft seal, and from the side of the turbine wheel by a discharge disk with its seal, an external supply path to the separation cavity and the turbine bearing cavity, the unloading disk with its seal is aligned with the turbine wheel, the shaft seal diameter is made less than the shaft diameter at the site of the turbine bearing seat, and the turbine bearing is installed on the pump side behind the separation cavity. (RF patent 2299344 C1. A device for separating a pump and a turbine of a booster turbopump unit of a liquid-propellant rocket engine., Published: 20.05.2007, Bul. No. 14 - prototype).

BTNA with such a pump-turbine separation device has the following disadvantages:

- during BTNA operation, cold leakage from the cavity of the unloading disk enters the turbine wheel, which leads to an umbrella effect - thermal deformations and stresses in the disk and blades of the turbine wheel;

- leakage of the liquid component from the separation cavity into the cavity of the BTNA turbine reduces its efficiency;

- the presence of an external supply path to the separating cavity and the bearing cavity of the BTNA turbine complicates the design of the engine, since it requires the inclusion of a separate line in the engine for supplying a high-pressure liquid component from the main turbo pump unit to the BTNA;

- the force of unloading the bearings from the action of axial forces is determined by the pressure of the supplied component and the diameter of the seal on the disc of the BTNA turbine wheel driven by the gas turbine, however, the higher the pressure of the fuel supplied to unload the component, the more power is lost on the main turbopump unit, and the larger the diameter of the seal, the lower the efficiency of the BTNA turbine and the higher the thermal stresses in the turbine wheel;

- leaks into the pump cavity of the component supplied to unload the bearings, lead to a decrease in the overall efficiency of the engine power supply system;

- leaks into the turbine cavity of the component supplied to unload the bearings, lead to a decrease in its efficiency; in a BTNA LPRE with a thrust of less than 0.5 MN, a decrease in leakages from the separation cavity into the turbine cavity is especially important, since these leaks in magnitude can be comparable to the flow rate gas through the turbine.

The objective of the present invention is to eliminate the above disadvantages of the device for separating the pump and turbine BTNA LPRE, to reduce power losses spent on separating the pump and turbine, to increase the efficiency of the power supply system, to reduce thermal deformations of the gas turbine impeller, to reduce the force acting on the bearings from axial forces.

The technical effect is achieved by the fact that in a BTNA LPRE containing a pump, a turbine, a turbine bearing, a pump bearing, a separation cavity between the pump and a turbine, limited from the turbine side by a shaft seal, the turbine bearing is installed on the pump side behind the separation cavity according to the invention, the separation cavity is located between with a turbine bearing and a shaft seal, on the turbine side, a discharge disc is installed in the separating cavity, on the outer diameter of which a seal is made, and the separating cavity in the peripheral part is connected by outlet channels with the pump outlet.

To reduce the axial thrust towards the pump inlet:

- on the side of the turbine, an additional unloading cavity can be made adjacent to the turbine wheel disc, limited by seals along the shaft and a seal on the turbine wheel disc, connected by channels to the gas supply manifold to the turbine;

- an axial spring can be installed between the turbine bearing and the pump bearing;

- blades or ribs can be made at the end of the unloading disk from the pump side;

- blades or ribs can be made on the end of the body adjacent to the unloading disc from the turbine side;

- blades or ribs can be made at the end of the unloading disc from the pump side and in the housing adjacent to the unloading disc from the turbine side.

A longitudinal section of the proposed booster turbopump unit of the LPRE is shown in Fig. 1, FIG. 2, 3 - options for BTNA with blades / ribs at the end of the body, an additional unloading cavity, where:

1 - turbine;

2 - pump;

3 - separation cavity between the pump and the turbine;

4 - shaft seal;

5 - unloading disc;

6 - seal of the unloading disk;

7 - turbine bearing;

8 - pump bearing;

9 - outlet channels to the pump outlet;

10 - pump outlet;

11 - blades / ribs on the unloading disc;

12 - blades / ribs in the body;

13 - pump impeller;

14 - turbine wheel disc;

15 - additional unloading cavity of the turbine wheel disc;

16 - seal on the turbine wheel disc;

17 - turbine inlet manifold;

18 - gas supply channels.

The booster turbopump unit (Fig. 1) consists of a turbine 1, a pump 2 between which there is a separation cavity 3, bounded from the turbine side by a shaft seal 4. In the separation cavity 3 there is a discharge disc 5, on the outer diameter of which there is a seal 6. The shaft is mounted on turbine bearing 7 and pump bearing 8. In the peripheral part, the separation cavity is connected by outlet channels 9 with a pump outlet 10. To increase the unloading capacity, blades or ribs 11 can be made at the end of the unloading disk on the pump side, for the same purpose, the blades or ribs can be are made on the end of the housing 12 from the side of the unloading disk 5 (Fig. 2) facing the turbine. The vanes / ribs 11 at the end of the unloading disc and the vanes / ribs 12 at the end of the housing can be made both separately and together. Pump 2 includes a pump impeller 13.

In an embodiment of the invention, the booster turbopump unit (Fig. 3) consists of a turbine 1, a pump 2 between which there is a separation cavity 3, bounded from the turbine side by a shaft seal 4. In the separation cavity 3 there is a discharge disc 5, on the outer diameter of which there is a seal 6 The shaft is mounted on the turbine bearing 7 and the pump bearing 8. In the peripheral part, the separating cavity is connected by the outlet channels 9 with the pump outlet 10. To increase the unloading capacity at the end of the unloading disc on the pump side, blades / ribs 11 can be made, for the same purpose blades / ribs 12 can be made at the end of the housing from the side of the unloading disk 5 facing the turbine. The vanes / ribs 11 at the end of the unloading disc and the vanes / ribs 12 at the end of the housing can be made both separately and together. Pump 2 includes a pump impeller 13. For additional compensation of the axial force acting on the bearings 7 from the turbine side, an additional unloading cavity 15 is used at the turbine wheel disk 14, limited by the shaft seal 4 and the seal on the turbine wheel disk 16, connected to the collector gas supply to the turbine with 17 channels 18.

During the operation of the BTNA (Fig. 1), the working fluid of the high-pressure pump enters the separation cavity 3 from the side of the pump 2 to the unloading disk 5 after the impeller of the pump 13 from the outlet of the pump 10 through channels 9, and from the side of the turbine 1 through the shaft seal 4 to the unloading disk 5 is supplied with gas from the turbine. Due to the rotation of the rotor, the unloading disc 5 creates an additional head, the pressure on its outer diameter exceeds the pressure at the pump outlet 10 and the pressure at the outlet of the seal 4, which excludes gas breakthrough into the cavity of the pump impeller. The leakage of the working fluid from the unloading cavity is limited by the seal 6 on the unloading disc. From the unloading cavity 5, the mixture of the working fluid of the pump and gas from the turbine through the outlet channels 9 enters the outlet of the pump 10, where it mixes with the main flow. When mixed with a liquid component, the gas condenses and the working fluid in the liquid phase enters the pump inlet of the main turbo pump unit. Since the gas leak from the turbine through the shaft seal 4, compared to the flow through the BTNA pump, is small, it does not significantly affect the characteristics of the main pump of the turbo pump unit. During operation, an axial force acts on the impeller of the pump 13, created by the pressure difference acting on it. This force is directed away from the outlet to the inlet of the pump. In the turbine 1, operating at a low pressure drop, an axial force acts on the disk of the turbine wheel 14, directed in the same direction as the axial force acting on the pump impeller 13. Axial forces acting on the turbine wheel disk 14 and the pump impeller 13, are balanced by an axial force acting on the unloading disc 5 and directed in the opposite direction, i.e. from the inlet to the outlet of the pump, which reduces the axial force acting on the bearings 7 and 8. To increase the unloading ability of the unloading disc 5, blades or ribs 11 can be made in the unloading disc from the pump side to increase the pressure over the disc surface. To equalize the pressure on the surface of the disk from the turbine side, blades or ribs can be made on the end of the housing 12 from the side of the unloading disk facing the turbine (Fig. 2). The blades / ribs 11 in the unloading disk and the blades / ribs 12 at the end of the housing can be made both separately and together, depending on the pressure distribution in the cavities of the pump and the BTNA turbine. The area of the unloading disk 5 is determined by the value of the axial force required to balance the axial forces acting on the disk of the turbine wheel 14 and the pump impeller 13.

When operating the BTNA version with increased unloading capacity (Fig. 3), the working fluid of the high-pressure pump enters the separation cavity 3 from the pump 2 side to the unloading disk 5 after the pump impeller 13 from the pump outlet 10 through channels 9, and from the turbine 1 side through shaft seal 4, gas flows from the turbine to the unloading disc 5. Due to the rotation of the rotor, the unloading disc 5 creates an additional head, the pressure on its outer diameter exceeds the pressure at the pump outlet 10 and the pressure at the outlet of the seal 4, which excludes gas breakthrough into the cavity of the pump impeller. The leakage of the working fluid from the unloading cavity is limited by the seal 6 on the unloading disc. From the unloading cavity 5, the mixture of the working fluid of the pump and gas from the turbine through the outlet channels 9 enters the outlet of the pump 10, where it mixes with the main flow. When mixed with a liquid component, the gas condenses and the working fluid in the liquid phase enters the pump inlet of the main turbo pump unit. Since the gas leak from the turbine through the shaft seal 4, compared to the flow through the BTNA pump, is small, it does not significantly affect the characteristics of the main pump of the turbo pump unit. During operation, an axial force acts on the impeller of the pump 13, created by the pressure difference acting on it. This force is directed away from the outlet to the inlet of the pump. In the turbine 1, operating at a low pressure drop, an axial force acts on the disk of the turbine wheel 14, directed in the same direction as the axial force acting on the pump impeller 13. Axial forces acting on the turbine wheel disk 14 and the pump impeller 13, are balanced by an axial force acting on the unloading disc 5 and directed in the opposite direction, i.e. from the inlet to the outlet of the pump, which reduces the axial force acting on the bearings 7 and 8. To increase the unloading ability of the unloading disc 5, blades or ribs 11 can be made in the unloading disc from the pump side to increase the pressure over the disc surface. To equalize the pressure on the surface of the disk from the turbine side, blades or ribs 12 can be made at the end of the housing from the side of the unloading disk facing the turbine. The blades / ribs 11 in the unloading disk and the blades / ribs 12 at the end of the housing can be made both separately and together, depending on the pressure distribution in the cavities of the pump and the BTNA turbine. Additionally, to reduce leaks of the pump working fluid from the separation cavity between the pump and turbine 3 into the pump outlet 10 and increase the overall unloading capacity into the unloading cavity of the turbine disk 15, limited by the turbine wheel disk 14, the shaft seal 4 and the seal on the turbine wheel disk 16, from the manifold the supply of the turbine 17 through the supply channels into the unloading cavity of the disk of the turbine 18 high pressure gas enters. In the additional unloading cavity 15, an axial force is created, directed in the direction opposite to the outlet from the pump, the value of which is determined by the diameters of the shaft seal 4 and the seal on the disk of the turbine wheel 16. The area of the unloading disk 5 and the diameter of the seal on the disk of the turbine wheel 16 are determined by the value of the axial force required to balance the axial forces acting on the turbine wheel disk 14 and the pump impeller 13.

The advantage of the reduced booster turbopump unit of a liquid-propellant engine, in contrast to the prototype, where the unloading of bearings from the action of axial forces is provided by supplying a high-pressure working fluid from the outlet of the pump of the main turbo-pump unit, is:

- no cold leakage of the working fluid from the separation cavity 3 to the disk of the turbine wheel 14, which excludes the occurrence of the umbrella effect - thermal deformations and stresses in the turbine wheel;

- no leakage of the liquid component from the separation cavity 3 into the turbine cavity, which allows for high efficiency of the turbine;

- absence of leakage of the component supplied for unloading the bearings into the pump cavity ensures high efficiency of the BTNA pump;

- implementation of axial unloading of the supports due to the organization of the working process inside the unit;

- elimination of the supply of the high-pressure liquid component to the separation cavity between the pump and the turbine, which required the inclusion of a separate line of the high-pressure liquid component from the main turbopump unit to the BTNA into the engine;

- ensuring the magnitude of the unloading force of the bearings from the action of axial forces by choosing the diameter of the unloading disc, the area of the unloading cavity (diameters of the shaft seal 4 and the seal on the turbine wheel disc 16), the force of the axial spring.

Thus, the implementation of the booster turbopump unit of the liquid-propellant engine will provide minimal power losses associated with the unloading of bearings from the action of axial forces while ensuring their reliable unloading and a general increase in the efficiency of the liquid-propellant engine power system.

Claims (8)

1. Booster turbopump unit of a liquid-propellant rocket engine, containing a pump, a turbine, a separation cavity between the pump and the turbine, limited from the turbine side by a shaft seal, a turbine bearing mounted on the pump side behind the separation cavity, characterized in that the separation cavity is connected by channels to the pump outlet and a relief disc is placed in it, on the outer diameter of which a seal is made. 2. The booster turbopump assembly of a liquid-propellant rocket engine according to claim 1, characterized in that blades or ribs are made at the end of the unloading disk from the pump side. 3. The booster turbopump unit of a liquid-propellant rocket engine according to claim 1, characterized in that blades or ribs are made at the end of the housing adjacent to the unloading disc from the turbine side. 4. The booster turbopump assembly of a liquid-propellant rocket engine according to claim 1, characterized in that blades or ribs are made at the end of the unloading disc from the pump side and on the end of the housing adjacent to the unloading disc from the turbine side. 5. Booster turbopump unit of a liquid-propellant rocket engine, containing a pump, a turbine, a separation cavity between the pump and the turbine, limited from the turbine side by a seal along the shaft, a turbine bearing installed on the pump side behind the separation cavity, characterized in that the separation cavity is connected by channels with a branch pump and a discharge disk is placed in it, on the outer diameter of which a seal is made, and an additional discharge cavity is made on the side of the turbine, adjacent to the disk of the turbine wheel, limited by the shaft and disk seals of the turbine wheel and connected by channels to the gas supply manifold to the turbine. 6. The booster turbopump unit of a liquid-propellant rocket engine according to claim 5, characterized in that blades or ribs are made at the end of the unloading disk from the pump side. 7. The booster turbopump assembly of a liquid-propellant rocket engine according to claim 5, characterized in that blades or ribs are made at the end of the housing adjacent to the unloading disk from the turbine side. 8. The booster turbopump assembly of a liquid-propellant rocket engine according to claim 5, characterized in that blades or ribs are made at the end of the unloading disc from the pump side and on the end of the housing adjacent to the unloading disc from the turbine side.

Images