RU2260135C1 - Gas-turbine engine starting system - Google Patents

Abstract

FIELD: aircraft engineering; aircraft engines.

SUBSTANCE: invention relates to starting systems of aircraft engines. Proposed starting system of gas-turbine engine contains auxiliary power plant including compressor and flame tube of combustion chamber, and starting device with air turbine connected by main pipeline with compressor of auxiliary power plant through shutoff device. Starting system is furnished with additional pipeline communicating through its input with inner space of flame tube of auxiliary power plant combustion chamber, and through output, with inner space of main pipeline. Shutoff device is arranged in main pipeline and air turbine of starting device.

EFFECT: increased power output of auxiliary power plant without considerable changing of its overall dimensions and weight, improved reliability of engine starting and reduced time taken for starting.

5 cl, 2 dwg

Description

The invention relates to the field of aircraft engine construction, in particular to gas turbine engine starting systems.

A known system for starting a gas turbine engine containing an auxiliary power unit (hereinafter referred to as APU), including a compressor and a heat pipe of a combustion chamber, and a starting device with an air turbine connected via a main pipeline through a locking device to an auxiliary power unit compressor (B.M. Katz, E.S. Zharov, V.K. Vinokurov, Launching Systems for Aircraft Gas Turbine Engines, - M.: Mechanical Engineering, 1976, p. 7-9).

In the known device as a starting device, an air starter is used, mechanically connected to the shaft of the rotor of the engine. The starting device spins the engine rotor until the moment when the turbine begins to develop power sufficient to independently spin the engine rotor with a given acceleration, after which it turns off.

The main disadvantage of the known device is the reduction in the power supplied to the rotor of the engine due to the low level of energy efficiency of the APU, which leads to an increase in the start time of the engine and a decrease in its reliability. However, to ensure the required characteristics of the launch of a gas turbine engine, it is necessary to increase the power of the APU, while increasing its dimensions, weight and cost.

The problem to which the claimed invention is directed is to increase reliability and reduce engine start time without significant changes in dimensions and weight of the original APU.

The problem is solved in that the gas turbine engine start-up system, comprising an auxiliary power unit including a compressor and a combustion chamber heat pipe, and a starting device with an air turbine connected via a main pipeline through a shut-off device to an auxiliary power unit compressor, is equipped with an additional pipeline communicated with its input with the internal cavity of the flame tube of the combustion chamber of the auxiliary power unit, and the output with the internal cavity of the main pipe water, wherein the locking device is arranged in the main conduit between the outlet conduit and the additional air turbine starter unit.

In addition, the following may occur in the device:

- an additional pipeline can be placed in the internal cavity of the main pipeline;

- in the inner cavity of the main pipeline between the locking device and the output of the additional pipeline can be placed profiled tapering-expanding nozzle type venturi;

- a profiled tapering-expanding nozzle such as a venturi can be equipped with a mechanism for moving it along the axis of the main pipeline;

- on the outer surface of the additional pipeline in the area of its exit, a profiled insert can be placed.

Equipping the engine with an additional pipeline and communicating through it the internal cavity of the combustion tube of the APU combustion chamber with the internal cavity of the main pipeline ensures the supply of hot gas to the pipeline in communication with the air turbine. An increase in the temperature of the working fluid supplied to the air turbine significantly increases its specific power, thereby increasing the level of power supplied to the rotor of the engine. The use of hot gas from the combustion chamber of the APU as a heated working fluid makes it possible to more fully use the potential capabilities of the APU itself. In this case, there is no need to change the design of the APU by introducing any elements of the heating of the working fluid.

Placing the shut-off device in the main pipeline between the outlet of the additional pipeline and the air turbine ensures the supply of the working fluid to the air turbine, as well as the cessation of this supply.

Placing an additional pipeline in the inner cavity of the main pipeline is most rational, because, firstly, it does not require additional space, and, secondly, it allows air passing through the main pipeline to cool the additional pipeline, which is very hot due to hot gases, providing him thereby thermal protection.

Placing in the inner cavity of the main pipeline between the locking device and the outlet of the additional pipeline a profiled tapering-expanding nozzle such as a venturi ensures minimal pressure loss of the working fluid supplied to the air turbine of the starting device.

Equipping a profiled tapering-expanding venturi-type nozzle with a mechanism for moving it along the axis of the main pipeline allows you to move the venturi along the section of the main pipeline, fixing its position relative to the output section of the additional pipeline. At the same time, in the position where the throat of the Venturi tube is located in the area of the outlet section of the additional pipeline, air is accelerated inside the Venturi tube and its static pressure is reduced, so that hot gas from the internal cavity of the combustion chamber enters the expanding section of the Venturi tube and mixes with air from the compressor .

Performing an additional insert pipe on the outer surface of the outlet section allows the venturi to be in the extreme position by contacting its inlet section with the insert to block the air flow through the main pipeline to the air turbine and to allow hot gas from the combustion chamber to open.

The invention is illustrated by drawings, where in FIG. 1 shows a general diagram of a gas turbine engine launch system, and FIG. 2 shows the possible positions of a profiled tapering-expanding nozzle such as a venturi in the main pipe.

The proposed system for starting a gas turbine engine contains an APU 1 with a compressor 2 and a combustion chamber 3 and an air turbine 4 of a starting device, a shaft 5 of which is mechanically connected to the rotor shaft 6 of the engine 7. The turbine 4 is connected to the compressor 2 of the APU 1 by a main pipe 8. In the inner cavity of the main of the pipe 8, a control valve 9 and an additional pipe 10 are placed, communicated by its inlet with the internal cavity of the combustion chamber 3, and the output with the internal cavity of the main pipe 8, as well as a profiled tapering - an expanding nozzle of the Venturi type 11. A control valve 9 is placed in the pipe 8 between the outlet of the additional pipeline 10 and the air turbine 4. A profiled tapering-expanding nozzle of the type of a Venturi 11 is equipped with a mechanism 12 for moving it along the axis of the main pipe 8, made in the form of a cylinder with the piston 13. On the outer surface of the additional pipeline 10 in the area of its exit into the internal cavity of the main pipeline 8 is placed a profiled insert 14.

The operation of the device is as follows.

The APU 1 is launched and displayed in steady state.

To spin the rotor 6 of the engine 7, a command is sent to the control valve 15 and the air through the pipe 16 enters from the compressor 2 to the cylinder 17, moving the stem 18 to the position in which the control valve 9 opens and provides air from the compressor 2 to the air turbine 4, which in turn, through the output shaft 5 is connected to the rotor 6 of the engine 7.

Thus, the air turbine 4 begins to spin the rotor 6. After this, a command is issued to open the control valve 19 and air from the compressor 2 through the pipe 20 enters the internal cavity of the mechanism 12, moving the rod 21 with the piston 13. At the same time, the air displaced by the piston 13 from the internal cavity of the mechanism 12, through the pipe 22 through the valve 19 is vented into the atmosphere.

Depending on the command of the starting block 23 of the engine 7, the rod 21 moves the venturi 11 from position 24 to position 25 or 26.

At position 25, the inner contour of the venturi 11 together with the output section of the additional pipeline 10 forms an ejector, where the air behind the compressor 2 performs the function of the ejection gas entering through the pipe 8, and the hot gas coming from the internal performs the ejected gas entering through the pipe 10 cavity of the flame tube of the combustion chamber 3.

The air from the compressor 2 in the venturi 11 accelerates, and its static pressure drops, reaching a minimum level in the outlet section of the section of the additional pipeline 10 and providing a pressure drop in the pipeline 10. Hot gas begins to flow into the venturi 11 and mixes with cooler air from compressor 2. At the same time, the fuel supply to the APU increases. 1. Further promotion of the engine 7 is performed by an air turbine 4. Upon reaching the specified engine speed 7, the drive is disconnected from the air of the turbine 4 and a command is given from the start block 23 to the control valve 19 and the air begins to flow into the cylinder cavity of the mechanism 12 through the pipe 22 and, moving the rod 21 with the piston 13, and through the pipe 27 is vented to the atmosphere. As a result, the venturi 11 takes its initial position 24. In this case, the flow of hot gas to the pipeline 8 stops, since with the movement of the venturi 11 the pressure at the outlet section of the pipeline 10 rises to the pressure level behind the compressor 2.

The pressure inside the flame tube of the combustion chamber 3 is lower than the pressure behind the compressor 2, so the air behind it begins to flow through the pipe 10 into the flame tube of the combustion chamber 3. A small difference in the pipeline 10 between the air and gas inside the flame tube of the combustion chamber 3 allows air to flow through it combustion tube 3.

Next, a command is sent from block 23 to the control valve 15 and air enters the cylinder 17, moving the rod 18 in the opposite direction to close the control valve 9 located in the main pipe 8, cutting off the air supply to the air turbine 4. At the same time, the bypass valve 28 opens.

In forced start-up modes, the venturi 11 is moved to position 26, its inlet section together with the insert 14 closes the pipeline 8, as a result of which air from the compressor 2 ceases to flow into the air turbine 4, and only hot gas from the inner cavity of the combustion tube’s combustion chamber enters 3. At the same time, the fuel supply to the combustion chamber 3 increases and the bypass valve 28 opens into the gas path of the APU 1.

The proposed system can significantly increase energy efficiency from the APU without significant changes in its dimensions and weight, thereby increasing the reliability of starting the engine, as well as reducing its time.

Sources of information

1. B.M. Katz, E.S. Zharov, V.K. Vinokurov. Starting systems for aircraft gas turbine engines, M.: Mechanical Engineering, 1976, p. 7-9.

Claims (5)

1. A gas turbine engine starting system comprising an auxiliary power unit including a compressor and a combustion chamber flame tube and a starting device with an air turbine connected via a main pipe through a shut-off device to an auxiliary power unit compressor, characterized in that it is equipped with an additional pipe connected its entrance with the internal cavity of the flame tube of the combustion chamber of the auxiliary power unit, and with the exit - with the internal cavity of the main pipe wires, and the locking device is placed in the main pipeline between the output of the additional pipeline and the air turbine of the starting device. 2. The system according to claim 1, characterized in that the additional pipeline is located in the inner cavity of the main pipeline. 3. The system according to claim 1 or 2, characterized in that in the inner cavity of the main pipe between the locking device and the output of the additional pipe is placed a profiled tapering-expanding nozzle such as a venturi. 4. The system according to claim 3, characterized in that the profiled tapering-expanding nozzle such as a venturi is equipped with a mechanism for moving it along the axis of the main pipeline. 5. The system according to claim 4, characterized in that on the outer surface of the additional pipeline in the area of its output, a profiled insert is placed.

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