RU2627627C1 - Aero bypass turbofan engine control method - Google Patents

Abstract

FIELD: engine devices and pumps.

SUBSTANCE: gas pressure is measured behind the low-pressure turbine, pressure ratio is determined behind the compressor and behind the low-pressure turbine, lower and upper threshold limit values of low-pressure rotor speed are set for each value of air temperature at the engine inlet with an allowable voltage level in moving blades. Control of low-pressure rotor speed is conducted by controlling the fuel flow to the combustion chamber and changing the area of the critical section of jet nozzle, determined by the ratio of pressures behind compressor and low-pressure turbine, while speed control is performed until low-pressure rotor speed reaches the maximum threshold values.

EFFECT: invention allows to achieve maximum value of draft under constraints on the controlled parameters values and control actions.

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Description

The invention relates to the field of aircraft engine manufacturing and can be used in electronic-hydromechanical systems for automatic control of twin-shaft turbojet engines with adjustable guides of the low-pressure compressor.

The closest to this invention in terms of technical nature and the technical result achieved is a known method for controlling a gas turbine engine, in which the rotational speed of the low pressure rotor (RND), the position of the throttle control lever of the engine, the temperature of the air at the engine inlet, the temperature of the gases behind the low pressure turbine are measured , regulate the rotational speed of the low pressure rotor, meter the fuel consumption in the combustion chamber, adjust the angle of installation of the input guide vanes of the compress ora low pressure.

The known device maintains a predetermined value of one of the engine parameters (speed of the low pressure switch, high pressure switch, temperature behind the turbine) by changing the fuel consumption.

The system that implements the above method contains in series: a block of gas temperature sensors behind a low-pressure turbine (DTT), rotational speed of a low-pressure rotor (DPC), air temperature at the engine inlet (DTX), parameter settings GTE (RND speed setter (Set Npnd), temperature setter behind the turbine (Set. Ttv)), blocks of regulators of the RND speed (set Npnd reg) and temperature behind the turbine (Ttr set), minimum selector (MIN) and a fuel management device (UU GT).

In the process, depending on the temperature measured at the TBX input by the TBx sensor, the setpoints Npnd and Ttv are set accordingly. The controller blocks, comparing the set values with the measured sensors, calculate the necessary effect on the fuel consumption meter to maintain each of the parameters, respectively. The minimum selector selects the minimum effect and feeds it to the fuel metering device, which provides a change in fuel consumption to maintain the value set by the master.

/ RU 115832 U1, "NLP Temp them. F. Korotkova, 05/10/2012 /

If in the region of maximum engine conditions there are restrictions on the range of compressor rotation frequencies, for example, due to the resonances of the blades, this control method is not optimal, since it does not allow maintaining the rotation frequency below or above the resonance region. A decrease in the rotational speed is undesirable due to loss of traction; the possibility of increasing the rotational speed is limited by the maximum permissible temperature of the gases behind the turbine.

The objective of the invention is the exclusion of engine operation in the resonance zone and thus increasing the service life while maintaining traction.

The expected technical result is to achieve maximum thrust when there are restrictions on the values of the adjustable parameters and / or control actions.

The expected technical result is achieved in that in a method for controlling an aircraft turbojet bypass engine, including measuring the rotational speed of the low pressure rotor, the air temperature at the engine inlet and the temperature of the gases behind the low pressure turbine, adjusting the rotational speed of the low pressure rotor, dosing the fuel consumption into the combustion chamber and changing the critical cross-sectional area of the jet nozzle, according to the invention, the gas pressure behind the low-pressure turbine is additionally measured I, determine the pressure ratio behind the compressor and behind the low-pressure turbine, for each air temperature at the inlet of the engine, set the lower and upper maximum permissible rotational speeds of the low-pressure rotor at an acceptable voltage level in the working blades, and the low-speed rotor rotational speed is controlled by adjusting the fuel consumption in the combustion chamber and changing the area of the critical section of the jet nozzle (PC), determined by the ratio of the pressures behind the compressor and behind the low-pressure turbine, while the speed control is performed until the rotational speed of the low-pressure rotor reaches the maximum permissible values.

Permissible voltage level is such a voltage level at which short-term operation for 5-10 s is possible, or the total operating time for the engine resource should not exceed 3-5 minutes.

The rotational speed of the low pressure rotor of the engine is determined by fuel consumption. The temperature limit sets the maximum allowable value of fuel consumption and, as a consequence, the maximum value of the speed of the RND. Achieving a predetermined speed above the resonance zone is achieved by controlling the critical cross-sectional area of the jet nozzle. The nominal position of the nozzle flaps, which determine the critical cross-sectional area, is formed depending on the set value of the ratio of the gas pressure behind the compressor to the gas pressure behind the low-pressure turbine (degree of expansion of pressure on the turbine - Fri), which depends on the temperature at the engine inlet. When you open the sash PC relative to the nominal value, the speed increases. It is necessary to determine the amount of opening of the shutters PC from the nominal position, which will ensure an increase in the speed to a predetermined value. It is impossible to calculate this value for all operating conditions, taking into account changes in characteristics as the engine reaches its life. Therefore, the problem is solved by an additional regulator, which opens the shutters PC to achieve a predetermined speed value.

The essence of the claimed invention is illustrated in FIG. 1 and FIG. 2.

In FIG. 1 is a diagram of a control system for an aircraft turbojet bypass engine.

In FIG. 2 shows the dependence of the set value of the rotational speed on the temperature at the engine inlet.

The regulation system of an aircraft turbojet dual-circuit engine (Fig. 1) is equipped with sensors for measuring its operation parameters, measured value adjusters, and gas-turbine engine parameters regulators:

1 - gas turbine engine,

2 - gas temperature sensor behind the low pressure turbine,

3 - speed sensor rotor low pressure,

4 - air temperature sensor at the engine inlet,

5 - gas pressure sensor behind the compressor (Pk),

6 - gas pressure sensor behind the low pressure turbine (Ptv),

7 - gas temperature setpoint behind the low pressure turbine,

8 - speed controller rotor low pressure,

9 - adjuster of the degree of expansion of gases on the turbines (the ratio of the gas pressure behind the compressor to the gas pressure behind the low pressure turbine),

10 - gas temperature limiter (Tg) behind the low pressure turbine,

11 - speed controller of the low pressure rotor,

12 - managed key,

13 is a summing amplifier,

14 - comparator,

15 - regulator Fri the degree of expansion of gases in turbines,

16 - minimum selector,

17 - fuel dispenser,

18 - drive leaf PC (DLS).

The specified engine operating mode is supported by the speed controller of the low-pressure compressor 11, which compares the speed set by the setter 8 and the speed value measured by the sensor 3 and generates a control signal to the fuel metering device 17.

The setter 8 generates a set value depending on the temperature measured by the sensor 4 at the inlet of the engine below or above the resonance region. The dependence of the setpoint value of the rotational speed on the temperature at the engine inlet is selected by calculation from the condition for achieving the optimum engine parameters, the nature of the dependence is shown in FIG. 2.

The gas temperature limiter behind the turbine 10 compares the gas temperature behind the turbine set by the setter 7 and measured by the sensor 2 and generates an output signal for controlling the dispenser to reduce fuel consumption when exceeding the maximum allowable gas temperature. A reduction in flow occurs until the temperature drops to an acceptable value.

The minimum selector 16 selects the smallest of the output signals of the speed controller 11 and the gas temperature limiter 10 and feeds it to the input of the fuel metering device 17. At the same time, while the gas temperatures behind the turbine are below the maximum permissible value set by the adjuster 7, the output signal of the minimum 16 selector is equal to the output the speed controller 11. This ensures that the frequency set by the speed controller 8 is set. Upon reaching the maximum value of the gas temperature, the minimum selector selects the output signal of the gas temperature limiter 10, and the speed starts to decrease below the value set by the frequency setpoint 8.

The setpoint Fri generates a set value for the position of the shutters PC depending on the temperature at the engine inlet measured by the sensor 4. The regulator Fri 15, based on the gas pressure measured by the sensor 5 behind the compressor and the gas pressure sensor 6 behind the low-pressure turbine, calculates the actual value Fri and compares it with the given setpoint Fri 9 and generates a control signal to the leaf drive PC 18 to maintain the set differential value.

If the output of the minimum selector 16 is equal to the output of the speed controller 11, the inputs of the comparator 14 are equal, and its output signal is logic zero. When this key 12 is open, and the output of the summing amplifier 13 is equal to its input. In this case, the shutters PC are installed in the position formed by the setter 9.

If the gas temperature behind the turbine reaches its maximum value and the output of the minimum 16 selector is equal to the output of the temperature limiter 10, the difference between the output signals of the minimum 16 selector and the speed controller 11 becomes positive. At the same time, a logic signal equal to 1 is generated at the output of the comparator 14. This signal is fed to the control input of the controlled key 12, which is closed and supplies a positive output signal of the speed controller to the summing input of the summing amplifier 13. The setpoint Pt increases, and the position controller 15 opens casement PC. As a result, the compressor speed rises until it reaches the value set by the frequency reference unit 8.

The proposed control method allows to exclude engine operation in the resonance zone, to achieve the maximum thrust value if there are restrictions on the values of the adjustable parameters and / or control actions.

Claims (5)

A method for regulating an aircraft turbojet bypass engine, including measuring the rotational speed of the low pressure rotor, the air temperature at the engine inlet and the gas temperature behind the low pressure turbine, adjusting the rotational speed of the low pressure rotor, dosing the fuel flow rate into the combustion chamber and changing the critical section area of the jet nozzle, characterized in that additionally measure the gas pressure behind the low-pressure turbine, determine the pressure ratio behind the compressor and behind the low-pressure turbine, for each value of the air temperature at the engine inlet, the lower and upper maximum permissible values of the rotational speed of the low pressure rotor are set at an acceptable level of voltage in the working blades, and regulation of the rotational speed of the low pressure rotor is carried out by adjusting the fuel consumption in the combustion chamber and changing the critical section area of the jet nozzle, determined by the ratio of the pressures behind the compressor and behind the low pressure turbine, while the rotational speed is controlled until the rotor speed of the low pressure is reached the maximum permissible values.

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