RU2845765C1 - Gas turbine engine fuel supply and control system - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to the field of gas turbine engines (GTE) fuel supply and control systems. It can be used at auxiliary power plants, turbo starters, engines, unmanned aerial vehicles, etc., where small dimensions and weight at low manufacturing costs are required. Impeller of electrically driven centrifugal pump is hydraulically connected to control cavity of fuel dispenser.

EFFECT: unambiguous dependence of the fuel consumption supplied to the gas turbine engine on the rotation frequency of the electric drive, which ensures reliable and simple control of the gas turbine engine modes.

2 cl, 2 dwg

Description

The invention relates to fuel supply and control systems for a gas turbine engine (GTE).

A fuel supply system for a gas turbine engine with an electrically driven high-pressure plunger pump is known (see application 2006116078/06, dated 10.05.2006, patent for invention RU 2322599 C2).

The disadvantages of this system are that plunger pumps are structurally complex, have a high manufacturing cost, are sensitive to fuel contamination, and have a high specific gravity. When used in aircraft gas turbine power systems, booster pumps (centrifugal pumps are most often used) must be used to provide the necessary pressure at the inlet of the plunger pump.

A fuel supply and control system for a gas turbine engine is known (see application 2011116006/06, dated 22.04.2011, patent for utility model RU 108 495 U1).

The disadvantages of this system are that gear pumps are technologically complex to manufacture. To ensure stable flow characteristics, the parts of the pumping unit of the gear pump must be made accurately, with small tolerances, and the manufacturing technology must provide small gaps between the moving parts of the pumping units.

To control the flow characteristics of a gear pump, a large volume of debugging and control bench tests of the system is required.

Also in systems with gear pumps for aircraft gas turbine engines, it is necessary to use booster pumps.

With long-term (long-life) use of systems with gear pumps, measures are required to control the performance of gear pumps.

Dynamic pumps are known that contain a booster stage, a main stage and an impeller (see p. 12 “High-speed vane pumps” edited by Ovsyannikov B.V., Chebaevsky V.F. M., “Mashinostroenie”, 1975).

The disadvantages of systems with dynamic pumps are that the relationship between the rotation speed, pressure and flow rate of a dynamic pump is expressed by a more complex mathematical relationship than in systems with plunger and gear pumps. For example, in the book by Mikhailov A.K., Malyushenko V.V. Vane pumps. Theory, calculation and design. - M.: Mashinostroenie, 1977. - 288 p. on page 129 there is an expression linking the pressure, rotation speed and productivity

Where - actual pressure,

- rotation frequency,

- productivity (volume flow),

, And - coefficients are constant for a given pump.

At the same time, in systems with plunger and gear pumps, the relationship between rotation speed and fuel consumption is close to linear.

The lack of a simple and unambiguous connection between rotation speed and fuel consumption leads to the complication of control algorithms, software, electronic regulators, and time spent on technological debugging of systems that use dynamic pumps.

A gas turbine fuel supply system with a centrifugal pump is known (see patent for invention RU 2329387 C2).

The disadvantages of this system are: that two control actions are used to change the fuel consumption: the pump rotation speed and the flow area of the fuel dispenser, made in the form of a throttling-type electromechanism. Moreover, with a constant position of the fuel dispenser and a variable rotation speed of the electric drive of the centrifugal pump, the system will provide a variable fuel consumption in the engine. That is, there is no feedback on the fuel consumption in the engine, therefore, an astatic control link is formed. This leads to a low stability margin of the regulator, necessary for stabilizing the dynamic characteristics of the system, which ultimately leads to a decrease in the reliability of the system.

The proportional electromagnets and linear motors included in the throttle-type electromechanism are complex and expensive devices. Accordingly, the use of a throttle-type electromechanism increases the weight and dimensions of the fuel supply system, as well as its cost. Also, the electromechanisms of throttle devices have a limited traction force, which worsens their dynamic characteristics.

In addition, the use of two control actions to manage fuel consumption leads to the complication of control algorithms, software, electronic regulators and system debugging technology.

The technical result that the invention is aimed at achieving is a simplified design, increased reliability, improved weight and size characteristics of the system, and a reduction in labor intensity and manufacturing costs.

In order to achieve the specified technical result in the fuel supply and control system of the gas turbine engine GTE, comprising a pump unit consisting of several dynamic stages, one of which is made in the form of an impeller, an adjustable electric drive kinematically connected to the pump unit, a control unit of the electric drive connected to the electronic regulator of the GTE, a fuel line hydraulically connecting the pump unit with the GTE, in which a fuel dispenser and a constant pressure difference valve on the fuel dispenser are installed, the impeller inlet is hydraulically connected to the spring cavity of the fuel dispenser, and the impeller outlet is hydraulically connected to the controlled cavity of the fuel dispenser. The fuel dispenser can also be equipped with a servomotor, the controlled cavity of the servomotor is hydraulically connected to the command spool valve, the fuel dispenser is mechanically connected to the command spool valve by a feedback spring, the impeller inlet is hydraulically connected to the command spool valve, and the impeller outlet is hydraulically connected to the control cavity of the command spool valve.

The distinctive features, namely: hydraulic connection of the input and output of the impeller with the spring and controlled cavities of the fuel dispenser, as well as the fact that the fuel dispenser can be equipped with a servomotor, the controlled cavity of the servomotor is hydraulically connected to the command spool, the fuel dispenser is mechanically connected to the command spool by a feedback spring, the input of the impeller is hydraulically connected to the command spool, and the output of the impeller is hydraulically connected to the control cavity of the command spool ensure:

- A clear connection between the rotation frequency of the electric drive and the fuel consumption in the engine, which ensures reliable and simple control of the gas turbine engine modes.

- Reduction of weight and structural complexity of the system by eliminating electromechanical control of the fuel dispenser.

- Simplification of the software used to manage fuel consumption.

- Simplification of the technological process of debugging the system during its design and manufacture.

- Possibility of selecting fuel for controlling devices of the hydromechanical part of the system.

In addition, the following is provided:

- Possibility of reducing the axial forces of the rotor of a dynamic pump by using an impeller stage.

- Possibility of increasing the volumetric efficiency of a dynamic pump by reducing leaks when using an impeller stage.

- Ability to operate at low fuel pressures and high pump rotation speeds.

- Reduction of the system weight by reducing the weight of the electric drive operating at high rotation speed.

- Less sensitivity to fuel contamination of the dynamic pump compared to plunger and gear pumps.

- Longer service life of a dynamic pump compared to plunger and gear pumps.

The proposed fuel supply and gas turbine control system is shown in the drawings and described below.

Depending on the maximum fuel consumption and the requirements for dosing accuracy, it is possible to implement a system with a direct-acting or indirect-acting fuel dispenser.

Fig. 1 shows a variant of the system with a direct-acting fuel dispenser, corresponding to the first point of the invention, and Fig. 2 shows a variant of the system with an indirect-acting fuel dispenser, corresponding to the second point of the invention.

The system shown in Fig. 1 contains a pump unit 1, which includes a booster stage 2, a main stage 3, an impeller 4, a fuel supply line 5, a fuel line 6, a constant differential valve (CDV) 7, a fuel dispenser 8, a nozzle 9 and a nozzle 10.

The input to the impeller 4 is hydraulically connected via channel 11 with the spring cavity 12 of the fuel dispenser 8. The output of the impeller 4 is hydraulically connected via channel 13 with the control cavity 14 of the fuel dispenser 8. The pump unit 1 is kinematically connected with the adjustable electric drive 15. The pump unit 1 is hydraulically connected via the outlet line 16 with the gas turbine engine 17.

The adjustable electric drive 15 is connected to the control unit 19 by electrical circuits 18. The electronic regulator (ER) 20 is connected by information exchange channels (IEC) 21 and 22 to the control unit 19 and the gas turbine engine 17.

The system shown in Fig. 2 also contains a servomotor 23 mechanically connected to the fuel dispenser 8, a command spool 24, a controlled cavity 25 of the servomotor 23 hydraulically connected to the command spool 24.

Feedback spring 26 mechanically connected to fuel dispenser 8 and valve 24.

The entrance to impeller 4 is hydraulically connected by channel 27 to spring cavity 28 of spring 26 and throttling section formed by the working edge of spool valve 24.

The output of impeller 4 is hydraulically connected via channel 29 to control cavity 30 of spool valve 24.

The system elements are shown in the drawings in the working position. The arrows show the direction of fuel movement in the fuel lines of the system.

The system works as follows.

Through the fuel supply line 5, the fuel is fed to the pump unit 1, which is driven into rotation by the adjustable electric drive 15. The booster stage 2, made in the form of a screw wheel, increases the fuel pressure and ensures cavitation-free operation of the main stage 3. Depending on the requirements for the system, the main stage 3 can be made centrifugal, vortex, or consist of several successive stages. From the main stage 3, the fuel is discharged into the injection line 6. The magnitude of the increase in fuel pressure by the pump unit 1 depends on the rotation frequency of the electric drive 15, as well as the fuel consumption supplied to the fuel outlet line 16, and on the operating mode of the gas turbine engine 17. The impeller 4 creates a fuel pressure that depends only on the rotation frequency of the electric drive 15. In this case, the dependence of the pressure drop between the input and output of the impeller 4 on the rotation frequency of the electric drive 15 is close to quadratic:

Where - pressure drop on impeller 4,

- electric drive rotation frequency 15.

If necessary, a fuel filter can be installed in the discharge line 6, not shown in the figures.

Fuel is supplied via injection line 6 to gearbox 7, then to fuel dispenser 8 and via outlet line 16 to gas turbine engine 17. The amount of fuel consumption in gas turbine engine 17 is determined by the cross-sectional area of fuel dispenser 8 and the pressure drop across it, maintained by gearbox 7.

The right cavity of the gearbox 7 is supplied with pressure at the inlet to the metering section of the fuel dispenser 8, and the left (spring) cavity of the gearbox 7 is supplied with pressure from the outlet of the metering section of the fuel dispenser 8. The gearbox 7 is in an equilibrium position when the pressure difference on the fuel dispenser 8 is equal to the specified value, and the force from the pressure difference on the fuel dispenser 8 is balanced by the force of the spring of the gearbox 7. If the pressure difference on the fuel dispenser 8 becomes less than the specified value, the gearbox 7 moves to the right by the force of the spring, and the area of the flow section of the gearbox 7 decreases, and the pressure difference on the flow section of the gearbox 7 increases, thereby compensating for the deviation from the specified value. If the pressure difference on the fuel dispenser 8 becomes greater than the specified value, the gearbox 7 moves to the left by the force of the spring, while the flow area of the gearbox 7 increases, and the difference on the flow area of the gearbox 7 decreases, thereby compensating for the deviation of the flow from the specified value.

Jet 9 ensures stable operation of gearbox 7 by damping pressure fluctuations in its spring cavity.

The pressure of the input to the impeller 4 is supplied to the spring cavity 12 of the fuel dispenser 8 via the channel 11, and the pressure of the output from the impeller 4 is supplied to the controlled cavity 14 of the fuel dispenser 8 via the channel 13. The force from the pressure difference on the impeller 4 is balanced by the force of the spring of the fuel dispenser 8. When the difference on the impeller 4 increases, the fuel dispenser 8 moves to the right to a new equilibrium position, compressing the spring. When the difference on the impeller 4 decreases, the fuel dispenser 8 moves to the left under the action of the spring to a new equilibrium position. The cross-sectional area of the fuel dispenser 8 depends on its position. Consequently, the dispenser 8 supplies fuel to the gas turbine engine 17 depending on the rotation frequency of the adjustable drive 15.

Jet 10 ensures stable operation of fuel dispenser 8 by damping pressure fluctuations in its spring cavity.

The profile of the flow section and, consequently, the size of the flow section area, as a function of the position of the fuel dispenser 8, ensures the desired dependence of the fuel consumption in the gas turbine engine 17 on the rotation speed of the adjustable drive 15.

The rotation frequency of the adjustable drive 15 is controlled by the control unit 19, sending electrical signals via the circuits 18. The parameters necessary for monitoring the operation of the adjustable drive 15, such as the temperature of the windings, can also be transmitted via the circuits 18. The control unit 19 also issues a feedback parameter characterizing the rotation frequency of the adjustable drive 15, to the ER 20 via the information exchange channel 21.

ER 20 implements the control program embedded in it based on external influencing factors and internal parameters of the gas turbine engine 17, received via the information exchange channel 22. If the calculated and specified parameters do not agree with the actual ones, ER 7, transmitting commands via the KIO 21 to the control unit 19, changes the fuel consumption in the GTE 17, adjusting the rotation frequency of the electric drive 15.

If necessary, the system can be implemented with an indirect-action dispenser; such a system is shown in Fig. 2.

In such a system, the position of the fuel dispenser 8 is determined by the pressure difference on the command spool 24 equal to the pressure difference between the input and output of the impeller 4. The input pressure of the impeller 4 is supplied to the spring cavity 28 of the spool 24 via channel 27, and the output pressure of the impeller 4 is supplied to the control cavity 30 via channel 29. The force from the pressure difference on the impeller 4, acting on the control spool 24, is balanced by the force from the feedback spring 26. The force from the feedback spring 26 changes proportionally to the stroke of the fuel dispenser 8.

With an increase in the rotation speed of the electric drive 15, the pressure difference on the impeller 4 increases, the force from the pressure difference overcomes the force of the feedback spring 26 and moves the command spool valve 24. The spool valve 24 reduces the fuel bypass from the controlled cavity 25 of the servomotor 23 to the channel 27. The pressure in the controlled cavity 25 of the servomotor 23 increases. The servomotor 23 moves the fuel dispenser 8, the feedback spring 26 is compressed until the movable elements take a new equilibrium position. In this case, an increase in the rotation speed of the electric drive 15 will correspond to an increase in the fuel consumption supplied to the gas turbine engine 17 via the line 16, which is determined by the profile of the dispenser 8.

When the rotation speed of the electric drive 15 decreases, the pressure difference on the impeller 4 decreases, the force from the feedback spring 26 overcomes the force from the difference on the spool 24, which moves, increasing the fuel bypass from the controlled cavity 25 of the servomotor 23. The pressure in the controlled cavity 25 decreases. The servomotor 23 moves the fuel dispenser 8 to a new equilibrium position, reducing the fuel consumption, in accordance with the profile of the metering section.

The operation of the remaining elements is similar to the operation of the elements of the system shown in Fig. 1.

Thus, the proposed system provides regulation and fuel supply of gas turbine engines.

The invention can be used in fuel supply and control systems: auxiliary power units, turbo starters, engines used in unmanned aerial vehicles, etc., where small dimensions and weight are required at low manufacturing costs.

Claims (2)

1. A fuel supply and control system for a gas turbine engine (GTE) comprising a pump unit consisting of several dynamic stages, one of which is made in the form of an impeller, an adjustable electric drive kinematically connected to the pump unit, an electric drive control unit connected to an electronic GTE regulator, a fuel line hydraulically connecting the pump unit to the GTE, in which a fuel dispenser and a constant pressure differential valve on the fuel dispenser are installed, characterized in that the impeller inlet is hydraulically connected to a spring cavity of the fuel dispenser, and the impeller outlet is hydraulically connected to a controlled cavity of the fuel dispenser. 2. The system according to item 1, characterized in that the fuel dispenser is equipped with a servomotor, the controlled cavity of the servomotor is hydraulically connected to the command spool, the fuel dispenser is mechanically connected to the command spool by a feedback spring, the impeller input is hydraulically connected to the command spool, and the impeller output is hydraulically connected to the control cavity of the command spool.