RU2364738C1 - Fuel supply system of gas turbine engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: fuel supply system of gas turbine engine is intended for fuel systems of aircrafts, in which engines are located above the main fuel tanks. System comprises the main pump-controller with serially installed make-up centrifugal and gyrating stages. Relief valve with servopiston is installed at gyrating stage. Inlet of valve via filter is connected to outlet of gyrating stage, and its outlet - to its inlet. Piston cavity of servopiston is connected to inlet of centrifugal stage, and stem cavity of valve - to its outlet. Valve is controlled by value of difference at centrifugal stage.

EFFECT: increased reliability of system operation in case of release of air dissolved in fuel, or in case of inlet pipeline damage, and also to reduce system weight and consumed power.

1 dwg

Description

The invention relates to the field of engine building, in particular to systems for supplying fuel to gas turbine engines (GTE). Its most appropriate use for the fuel systems of aircraft, in which the engines are located above the main fuel tanks, for example in helicopters.

A known system for supplying fuel to the gas turbine engine of the Mi-8 helicopter (see "Mi-8 helicopter. Technical description. Book 1: Flight performance.", M., "Engineering", 1970), containing suspended tanks with electric pumping pumps, a supply tank with booster electric drive pumps, a filter unit, a pump regulator driven by a gas turbine engine.

The disadvantages of this system are:

- If the booster pumps fail and the flight altitude exceeds 1000 m, the engine can stop. This is due to a decrease in fuel pressure at the inlet to the high-pressure pump (see I. Keba "Flight operation of helicopter gas turbine engines", Moscow, "Transport", 1976, p. 116).

- In case of damage (with loss of tightness) of the pipelines and the supply tank, fuel fills the internal space of the fuselage and the cargo compartment, which is extremely dangerous in terms of fire (see Volodko A.M., Gorshkov V.A. "Helicopter in Afghanistan", M., Military Publishing, 1993, p. 88).

Also known is a system for injecting fuel into an engine (see US patent No. 5490387, class F02C 7/22, 1996), which contains a pipeline for supplying fuel from the fuel tank to the engine, a fuel booster (booster) pump, a main fuel pump and a fuel a battery located between the booster pump and the main fuel pump, providing backup fuel supply to the engine, a return channel connected to the battery and the fuel supply pipe to the booster pump for supplying undissolved fuel vapor from the batteries pa. The booster pump is made in the form of a centrifugal pump with side channels having a satisfactory self-priming ability and a relatively constant outlet pressure.

The disadvantages of this system are:

- The complexity of the design and weight gain when using a centrifugal pump with side channels.

- Worse cavitation characteristics of a centrifugal pump with side channels compared to a conventional centrifugal pump.

- The presence of a fuel accumulator, weighting and complicating the system.

- A fuel accumulator, in case of loss of tightness, is more fire hazard compared to a supply tank due to the presence of internal pressure.

The technical result to which the invention is directed is to increase the reliability of the fuel supply system and reduce the weight of the system as a whole.

To achieve the specified technical result in the fuel supply system of a gas turbine engine containing a booster pump and a main pump-regulator installed in series, the booster pump is made in the form of centrifugal and rotary stages installed in series, the rotary stage is additionally equipped with a bypass piston valve, and the bypass valve input through the filter connected to the output line of the rotary stage, the output is to the entrance to the rotary stage, the piston cavity is servo shnya channel connected to the inlet manifold of the centrifugal stage, and the cavity stem valve - to the output pipe of the centrifugal stage.

Distinctive features, namely, that the booster pump has centrifugal and rotary stages installed in series, and the rotary stage is equipped with a bypass piston valve, and the bypass valve inlet through the filter is connected to the output manifold of the rotary stage, and the output is connected to the entrance to the rotary stage, the piston cavity of the servo piston is connected by a channel to the inlet line of the centrifugal stage, and the rod cavity of the valve is connected to the outlet line of the centrifugal stage, they allow controlling the valve bypass and fuel-largest drop in the centrifugal pump, which increases reliability and reduces weight. This is achieved by the fact that:

- The centrifugal stage is characterized by low sensitivity to fuel pollution and cavitation, simplicity of design, low specific gravity.

- The rotary stage has a good suction capacity, as well as a simple design compared to other types of volumetric pumps.

- Installing the rotary stage behind the centrifugal one allows you to ensure that the system is filled with fuel at the start.

- Also, the rotary step ensures reliable centrifugal operation when air is dissolved in the fuel.

- Ensures the cessation of fuel supply in case of violation of the tightness of the fuel supply line.

- A single drive of centrifugal and rotary steps allows to reduce the weight of the system as a whole.

- The joint operation of the centrifugal and rotary steps allows to ensure their reliable operation at a higher rotational speed of the drive, thereby reducing their weight and dimensions.

- The joint operation of the centrifugal and rotary stages allows the use of the rotary stage of lower productivity, which reduces the weight of the system as a whole.

- The installation of a fuel bypass valve, controlled by the difference in the centrifugal stage, allows for reliable operation and an increase in the resource of the rotary stage due to fuel cleaning by the filter.

- Installing a fuel bypass valve, controlled by the difference in the centrifugal stage, allows to reduce the power consumed by the rotary stage.

The proposed system is presented in the drawing and described below.

The system includes a booster pump 1 and a main pump-regulator 2. The booster pump 1 consists of a centrifugal stage 3 and a rotary stage 4 connected in series, connected by a drive shaft 5 to a gas turbine engine (not shown), and a bypass valve 6. Inlet line 7 of the bypass valve 6 through a self-cleaning filter 8 is connected to the output line 9 of stage 4. The output line 10 of the bypass valve 6 is connected to the input line 11 of the stage 4. The bypass valve has a servo piston 12, and the valve piston cavity 13 and 6 is connected by a channel 14 for supplying pressure to the input line 15 of the centrifugal stage 3, and the cavity 16 of the valve stem 6 is connected by a channel 17 to the output line 18 of the stage 3. A spring 19 is installed in the piston cavity 13. The line 15 is connected to the fuel tank 20. The check valve 21 installed between the lines 18 and 22. The check valve 23 is installed between the lines 24 and 25.

The fuel system may also have a main filter 26 and an air separator 27. A pipe 28 connects the air separator 27 to the tank 20.

The rod cavity 16 can be connected to the piston cavity 13 by a nozzle, which serves to remove air when filling the system with fuel.

Valves 21 and 23 can be replaced by grooves made on the valve stem 6.

The system operates as follows.

In the absence of pressure in the system, the valve 6 is closed by the force of the spring 19, the lines 7 and 10 are disconnected.

At the beginning of the start-up or cold-scrolling of the engine, the rotary stage 4 pumps out the air and ensures filling with fuel:

- highways 7, 9, 10, 11, 14, 15, 17, 18, 22, 24 and 25;

- the internal cavities of the valves 6, 21 and 23,

- internal cavities of the centrifugal stage 3;

- the internal cavities of the filters 8 and 26.

Air is displaced by the fuel into the air separator 27 and is discharged through the line 28 into the fuel tank 20.

During engine starting, the speed of the drive shaft 5 is low (about 10% of the maximum). Since the pressure created by the centrifugal stage 3 is approximately proportional to the square of the rotational speed of the drive shaft 5, the total force from the pressure of the fuel supplied to the inlet to the valve 6, and from the pressure of the fuel supplied to the rod cavity 16, is less than the total force from the fuel pressure, supplied to the piston cavity 13, and the efforts of the spring 19. In this case, the valve 6 is closed, lines 7 and 10 are disconnected. Kolovratovaya stage 4 provides the necessary amount of fuel on the lines 9, 24, 25 through the valve 23 and filters 8, 26 in the pump-controller 2 and ensures its cavitation-free operation. The valve 21 prevents the flow of fuel through the impeller of the centrifugal pump 3.

After starting the engine and increasing the speed of the drive shaft 5, the pressure created by the centrifugal step 3 increases. When the total force from the fuel pressure supplied to the inlet to the valve 6 and from the fuel pressure supplied to the rod cavity 16 becomes greater than the total force from the fuel pressure , supplied to the piston cavity 13, and the efforts of the spring 19, the valve 6 opens and connects the lines 7 and 10. At the same time, the valve 21, tuned to a lower opening pressure than the valve 23, opens and the valve 23 closes. The centrifugal stage 3 ensures the supply of the required amount of fuel along the lines 18, 22 through the valve 21 and the filter 26 to the pump-controller 2 and ensures its cavitation-free operation. The fuel passing through the rotary stage 4, with the valve 6 open, circulates along the lines 9, 7, 10, 11 and is cleaned by passing through the filter 8.

Filter 7 is self-cleaning. When the valve 6 is closed, when the fuel passes through the highways 9, 24, 25, the filter 8 is cleaned. The dirt particles washed off the filter 8 are delayed by the filter 26. When the valve 6 is open, when the fuel passes through the highways 9, 7, 10, 11 Filter 8 purifies the fuel circulating in a closed loop. This increases the life of the rotary stage 3.

As the altitude of the aircraft increases, the absolute pressure in the fuel tanks decreases. In this case, air dissolved in the fuel is released (the intensity of this process depends on the specific flight conditions). The ingress of a gas bubble into the centrifugal stage 3 leads to a pressure drop and a decrease in pressure in the output line 18. The total force from the fuel pressure supplied to the inlet to the valve 6, and from the fuel pressure supplied to the rod cavity 16, becomes less than the total force from the fuel pressure , introduced into the piston cavity 13, and the efforts of the spring 19. In this case, the valve 6 closes, separating the lines 7 and 10. The rotary stage 4 sucks the gas bubble from the centrifugal stage 4 and thereby prevents a prolonged decrease in pressure I fuel at the inlet to the pump regulator 2. When restoring the fuel pressure in the output line 18, the total force from the fuel pressure supplied to the inlet to the valve 6, and from the fuel pressure supplied to the rod cavity 16, becomes greater than the total force from the fuel pressure, supplied into the piston cavity 13, and the efforts of the spring 19. In this case, the valve 6 opens, connecting the line 7 and 10. The fuel passing through the rotary stage 4 with the valve 6 open, circulates along the lines 9, 7, 10, 11.

Valve 6 also limits the magnitude of the differential pressure difference between the input and output of the rotary stage 4.

Since there is no excess pressure in the line 15, in case of damage (with loss of tightness), fuel leakages from it are minimal. The feed pump 1 sucks out the remaining fuel from the damaged line 15, after which the gas turbine engine stops.

Claims (1)

The fuel supply system of a gas turbine engine comprising a sequentially installed booster pump and a main pump-regulator, characterized in that the booster pump has centrifugal and rotary stages mounted in series, the rotary stage is equipped with a bypass piston valve, and the bypass valve input through the filter is connected to the rotary output pipe stages, and the exit - with the entrance to the rotary stage, the piston cavity of the servo piston is connected by a channel to the input line centrifugally stage, and the cavity stem valve - channel with the output pipe of the centrifugal stage.

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