RU2328614C2 - Liquid-propellant rocket engine turbo pump unit hydrostatic bearing pneumohydraulic feed system - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to control and adjustment systems of liquid-propellant rocket engines, to be exact, to subsystems incorporated with the said systems and designed to control separate elements of the liquid-propellant rocket engine. The aforesaid feed system controls the turbo pump unit made up of a turbine, one or two pumps incorporating plain bearings, primarily, hydrostatic bearings with their inlets communicating hydraulically with high-pressure spaces and outlets communicating with low-pressure spaces of the aforesaid pumps, the bearings being lubricated by fuel components pumped over by the said pumps. Note, that the bearings of every pump communicate additionally via a valve train incorporating a pressurised fuel components feed devices allowing the bearings to run in starting up and shutting down. Note, also, that the pressurised fuel component devices are filled at a time with priming the pumps.

EFFECT: longer life of the turbo pump unit.

3 cl, 1 dwg

Description

The field of technology.

The invention relates to control systems and regulation of liquid rocket engines, and more specifically to subsystems that are part of these systems and designed to regulate individual elements of a liquid rocket engine.

State of the art

A technique is known in the art for the control and regulation of liquid-propellant rocket engines, for example, the RD-219 engine, the main elements of which, namely, sensors, throttle valves, various valves, including starting tank refueling valves, are shown on a simplified engine diagram (see the Cosmonautics Encyclopedia) . - M .: Soviet Encyclopedia, 1985, p. 330), a launch tank is also shown, in which, when launched, compressed fuel is displaced by a portion of the fuel necessary for pumping up. The specified scheme is taken as an analogue of the invention.

A disadvantage of the analogue is that the system does not allow directly affecting the operating conditions of the bearings of the turbopump assembly rotor, for example, regulating the supply of lubricant to the bearings regardless of the engine operating mode.

The control system and regulation of more advanced liquid-propellant rocket engines, for example, the RD-170 and RD-180 engines, the pneumohydraulic part of which is presented in the form of a circuit (see "Engines 1944-2000: aircraft, rocket, marine, industrial." M .: AKS-Conversalt, 2000, p. 269 and 270), which contains, among other elements, automation units, sensors, as well as a turbopump unit consisting of a turbine and fuel and oxidizer pumps, and, in addition, a component supply line fuels, “igniters” and launcher tank.

The system provides starting the engine, bringing it to the nominal operating mode, monitoring the parameters of the engine and its units, regulating the engine according to a given program and stopping it.

The specified system is taken as a prototype of the invention.

The disadvantage of the prototype, as well as the analogue, is that the system does not directly affect the working conditions of the bearings of the turbopump assembly rotor, for example, to regulate the supply of lubricant to the bearings regardless of the operating mode. This is due to the fact that due to weight and size limitations, their lubrication is carried out, as a rule, by the fuel components pumped by the pumps and the lubrication mode depends on the operation mode of the turbopump unit and, accordingly, the engine as a whole. This drawback is manifested to the greatest extent when using sliding bearings as a rotor, primarily hydrostatic bearings, the bearing capacity and dynamic characteristics of which directly depend on the pressure under which the lubricant is supplied.

Disclosure of invention

The present invention is aimed at solving the problem of increasing the resource of a turbopump assembly, the rotor of which is supported by sliding bearings, primarily bearings that use a hydrostatic method of lubrication, namely hydrostatic or hydrostatodynamic bearings, and which are lubricated by fuel components pumped by pumps turbopump unit.

It is known that the bearing capacity and dynamic characteristics of hydrostatic bearings depend on the lubricant pressure in the bearing pockets and, accordingly, on the lubricant supply pressure. In addition, such bearings are able, in the presence of an autonomous lubricant source, to “lift” the stationary shaft and start the unit without mechanical friction in the bearings.

When lubricating the bearings of a turbopump unit of a liquid propellant rocket engine with fuel components pumped by the corresponding pumps, the lubricant is supplied to the bearings from any high-pressure cavities, for example, from the pump outlet. Due to the fact that the head developed by the pump depends on the operating mode of the turbopump, or rather is proportional to the square of the rotor speed, the pressure in the cavities from which it is possible to select a fluid for lubricating the bearing, as well as the parameters of this fluid in the bearing cavities, will also depend from the operating mode of the turbopump unit.

Obviously, such a lubrication scheme for bearings leads to the fact that in the range of modes of a turbopump assembly characterized by rotational speeds from a fixed shaft position to a certain threshold value n _pores determined by the characteristics of pumps and bearings, the lubricant supply pressure will be insufficient to provide the hydrostatic pressure required for contactless operation bearing capacity. Therefore, in these modes, corresponding to the start and stop of the turbopump unit, the rotor will rotate with friction in the bearings, which can lead to undesirable wear on the working surfaces and reduce the life of the bearings.

Thus, to prevent wear, during the time required to accelerate the rotor from n = 0 rpm to n = n _pores and stop it from n = n _pores to n = 0 rpm, it is additionally necessary to apply pressure lubrication to the bearing sufficient to provide the necessary bearing capacity.

Given that

- the duration of the acceleration of the rotor of the turbopump unit to the rated speed is small and is a maximum of several seconds;

- the pressure of the component, sufficient for normal operation of the bearing, will be achieved at a rotational speed of the rotor less than the nominal;

- the lubricant consumption through the plain bearing is also small and depending on

bearing geometrical dimensions and lubricant supply pressure may be

in the range from fractions l / s to several l / s,

the total amount of grease that must be supplied to the bearings during start-up will be relatively small, on the order of several liters.

A slightly larger amount of grease will be required in the stop mode, since this mode has a longer duration.

Reducing the amount of lubricant stored in the system can be achieved by refueling the system while the engine is running. In this case, the volume of liquid in the system will be determined by one, the most continuous mode.

Since the bearings of each pump are lubricated by its fuel component, the proposed auxiliary system must be duplicated in the engine design as many times as the pumps are part of the turbopump, that is, in accordance with the number of fuel components used, or at least as many times as pumps have hydrostatic bearings as shaft supports. In this case, the degree of structural difference between the systems from each other will be determined by the degree of difference in the properties of the components used.

The stated technical problem is solved due to the fact that the pneumohydraulic power supply system for the hydrostatic bearings of the turbopump unit of a liquid rocket engine, containing as a control object a turbopump unit consisting of a turbine and one or two pumps containing sliding bearings, mainly hydrostatic bearings, the inputs of which are hydraulically connected to high-pressure cavities, and outputs - with low-pressure cavities of the respective pumps and lubricated by the pumped and pumps with fuel components, and the bearings of each pump are additionally hydraulically communicated through a valve system with displacing devices for the respective components, which ensure the bearings work in start and stop modes, while filling the displacing devices is carried out simultaneously with the pump.

Other differences of the proposed technical solutions are

- the fuel pump bearings are hydraulically connected to the cavity of the engine start tank;

- after the engine enters the mode, refueling is carried out

displacing devices for feeding components.

The technical result consists in performing a short-term lubricant feed (fuel components) of the hydrostatic bearings of the shaft of a turbopump assembly of liquid rocket engines in starting and stopping modes.

Brief Description of the Drawing

The drawing shows a pneumohydraulic power supply system for hydrostatic bearings of a turbopump unit of a liquid propellant rocket engine.

Description of the invention

The pneumatic-hydraulic power supply system for the hydrostatic bearings of a turbopump unit of a liquid propellant rocket engine includes a turbopump unit 1, which consists of a turbine 2 and oxidizer pumps 3 and fuel 4. The turbopump unit is shown the same as the prototype, although in general the number of pumps and their position relative to turbines may be different. Turbine 2 has a common shaft 5 with pump 3. Shaft 5 is supported by hydrostatic bearings 6 and 7, and shaft 8 of pump 4 is supported by bearings 9 and 10. Hydrostatic bearings 6 and 7 of pump 3 and bearings 9 and 10 of pump 4 have the same power system . Each of the supply systems includes a tank 11 (11 ') having two cavities - liquid 12 (12') and gas 13 (13 '), separated by an elastic diaphragm 14 (14'). The gas cavity 13 (13 ') is connected to the engine pneumatic system (not shown) through line 15 (15'). In addition, these systems include three non-return valves 16 (16 '), 17 (17') and 18 (18 '), and three highways 19 (19'), 20 (20 ') and 21 (21'). Designations without the index “″” refer to the power supply system of bearings 6 and 7, and with the index “» ”to the power supply system of bearings 9 and 10, respectively. As a lubricant for hydrostatic bearings, standard fuel components pumped by pumps are used. In this case, bearings 6 and 7 are lubricated by an oxidizing agent, and bearings 9 and 10 are combustible. Highways 19 (19 ') and 20 (20') connect the hydrostatic bearings 6 and 7 (9 and 10) through a non-return valve 16 (16 ') to the fluid cavity 12 (12') of the tank 11 (11 '), and through a non-return valve 17 (17 ') - with the outputs of the oxidizer pumps 3 and fuel 4. The check valve 18 (18') and line 21 (21 ') serve as refueling the fluid cavity 12 (12') of the tank 11 (11 ') with oxidizer (fuel) before starting the engine, and for refueling during engine operation.

Device operation

Before starting a liquid-propellant rocket engine, the oxidizer and fuel pumps are filled with standard fuel components. At the same time, the fuel components through the lines 21 and 21 'and check valves 18 and 18' are fed into the fluid cavities 12 and 12 'of the tanks 11 and 11'. When the engine is started, high pressure gas is supplied from the engine air system (not shown) through the lines 15 and 15 'to the gas cavities 13 and 13' of the tanks 11 and 11 '. As a result of this, the fuel components are displaced from the tanks 11 and 11 'through the valves 16 and 16' and the lines 19, 20 and 19 'and 20' into the hydrostatic bearings 6 and 7 of the oxidizer pump 3 and the bearings 9 and 10 of the fuel pump 4. Thus preliminary hydrostatic lifting of shafts 5 and 8 is provided.

After starting the engine, in the process of the turbopump unit reaching its nominal mode, the pressure at the outlet of the oxidizer 3 and fuel 4 pumps increases, the non-return valves 17 and 17 'are activated and these hydrostatic bearings are lubricated by the fuel components supplied from the outputs of the pumps 3 and 4, while check valves 16 and 16 'are closed and tanks 11 and 11' are cut off from the lines 19, 20 and 19 'and 20'.

During engine operation, refueling of tanks 11 and 11 'takes place through lines 21 and 21'.

When the engine is stopped, after reaching a rotor speed close to n _pores and a pressure drop at the outlet of pumps 3 and 4, high pressure gas is supplied to the tanks 11, 11 ', while the check valves 16 and 16' open and the hydrostatic bearings turn to grease fuel components supplied from the tanks 11 and 11 '.

The most easily proposed invention is implemented for a fuel pump, since there is a so-called so-called fuel line on the fuel supply line. a starting tank, which is precisely a device for displacing component feed, and used only in the process of starting the engine. The increase in its volume necessary to ensure the operation of the bearings in the start-up mode is small compared to its initial volume and will not lead to a significant increase in mass. At the same time, in the engine shutdown mode, the operation of the bearings is easily ensured due to the presence in the tank of a significant volume that is not used for operation of the engine itself, which after refueling the tank during engine operation can be used to increase the duration of the system.

For an oxidizer pump, a device like a starter reservoir is a newly introduced element and, naturally, will lead to a larger increase in mass. In addition, in the case of using a cryogenic component, the design of this device, which is different from the design of the existing launch tank, will be required, the creation of which is quite realistic, since analogues in cryogenic technology are known.

Industrial applicability

The invention is primarily intended for use in liquid-propellant rocket engines, mainly large thrust engines, for which the increase in mass associated with the introduction of additional units will be relatively small and have a turbopump unit whose rotor is supported by hydrostatic bearings lubricated by the pumped components of the fuel .

The invention can also be used for short-term lubrication of bearings of other types of bearings or friction units in units where the use of an autonomous permanent lubrication system is not possible due to any, for example, weight and size differences.

Claims (3)

1. A pneumatic-hydraulic power supply system for hydrostatic bearings of a turbopump unit of a liquid propellant rocket engine, comprising as a control object a turbopump unit consisting of a turbine and one or two pumps containing sliding bearings, mainly hydrostatic bearings, the inputs of which are hydraulically connected to the high-pressure cavities, and the outputs are with low-pressure cavities of the respective pumps and lubricated by the pumped components of the fuel components, characterized in that bearings each pump further fluidly communicated through a system of valves to supply the displacing devices of the respective components providing operation bearings on starting and stopping modes, thus filling feeders displacement is performed simultaneously with filling pumps. 2. The pneumatic-hydraulic power supply system of hydrostatic bearings according to claim 1, characterized in that the bearings of the fuel pump are hydraulically connected to the cavity of the engine start tank. 3. Pneumohydraulic power supply system for hydrostatic bearings according to claim 1 or 2, characterized in that after the engine enters the mode, refueling devices for the displacing components are refilled.