RU2255247C1 - Method to protect compressor at unsteady operation of gas- turbine engine - Google Patents

Abstract

FIELD: aircraft industry.

SUBSTANCE: invention relates to provision of flying safety of aircraft powered by gas-turbine engine. Proposed method to protect turbocompressor includes measuring air pressure after compressor (P_c), speed of pressure change

comparing the result with threshold value

forming signal to cut off fuel delivery to combustion chamber and switching on air bypass in compressor if value

is exceeded. Method provides additional measurement of speed of rotation of high-pressure rotor n_hp, comparing the result threshold value

. If

, signal to cut off fuel delivery into combustion chamber is blocked as well as signal to switch on air bypass in compressor.

EFFECT: improved flying safety owing to prevention of reduction of engine thrust below critical value at takeoff.

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Description

The invention relates to the field of ensuring flight safety of an aircraft with a gas turbine engine (GTE), in particular, by preventing surging of the compressor, characterized by strong low-frequency fluctuations in flow parameters in the flow section of the turbine engine.

Known methods for diagnosing and protecting a turbocharger turbine engine from surging, in which the following parameters are controlled:

- total air pressure behind the high-pressure compressor (P _kW );

- the frequency of rotation of the rotors of high and low pressure (n _vd , n _nd );

- the brightness temperature of the radiation of the heated surfaces of the structural elements of the gas turbine engine (T *) [1,2,3].

In the known methods, the principle of measuring the controlled parameters and / or their derivatives, the subsequent comparison of their actual values with the corresponding values of the maximum permissible (threshold) values, was used. If the actual values exceed the corresponding permissible values, a critical situation signal is given, indicating a loss of gas-dynamic stability.

However, the known methods do not provide for blocking a critical situation signal (“surge”) and / or actions performed by this signal, which in real conditions of engine operation on an airplane can lead to undesirable consequences (complication of piloting conditions, emergency, catastrophe).

Closest to the proposed one is a method of protecting a turbocharger from surging, according to which, when the controlled parameters exceed threshold values, a signal is generated to cut off the fuel into the combustion chamber and a signal to bypass the compressor [4]. The known method does not provide for blocking the generated signals to cut off the fuel into the combustion chamber and bypass the air of the compressor. That is, in real operating conditions, for example, during take-off during the formation of a critical situation signal (“surge”), the fuel supply to the engine may turn off. This will cause a sharp drop in engine thrust, as a result, complicating piloting conditions, an emergency, etc.

The technical problem solved by the invention is to increase flight safety by preventing the engine thrust from falling below a critical value during take-off.

сравнение с его пороговым значением

и формирование сигнала на отключение подачи топлива в камеру сгорания и включение перепуска воздуха в компрессоре при превышении величины

предполагает согласно изобретению, дополнительное измерение частоты вращения ротора высокого давления n_вд, сравнение его с пороговым значением

и в случае, если

блокировку сигнала на отключение подачи топлива в камеру сгорания и сигнала на включение перепуска воздуха в компрессоре.The essence of the invention lies in the fact that the method of protection of a turbocharger, including measuring the air pressure behind the compressor (P _k ), determining the rate of change

comparison with its threshold value

and generating a signal to turn off the fuel supply to the combustion chamber and enable air bypass in the compressor when the value is exceeded

involves, according to the invention, an additional measurement of the rotational speed of the high pressure rotor n _vd , comparing it with a threshold value

and in case

blocking the signal to turn off the fuel supply to the combustion chamber and the signal to turn on the air bypass in the compressor.

определяется допустимой величиной снижения режима при возникновении помпажа:Measurement of the rotational speed of the high-pressure rotor n _vd allows you to additionally control a parameter that characterizes the engine operating mode. The value of the threshold parameter

determined by the allowable amount of reduction in the event of a surge:

где

Where

- величина n_вд, соответствующая ограничиваемому “снизу” режиму двигателя во время взлета самолета (блокировка взлетного режима);

- the value of n _vd , corresponding to the limited “from below” engine mode during take-off (blocking the take-off mode);

Δn _vd is a constant value, depending on the type of engine.

блокировка сигнала на отключение подачи топлива в камеру сгорания и сигнала на включение перепуска воздуха в компрессоре позволяет предотвратить падение тяги двигателя ниже критического в процессе взлета, тем самым повысить безопасность полета.If

blocking the signal to turn off the fuel supply to the combustion chamber and the signal to turn on the air bypass in the compressor prevents the engine thrust from falling below critical during take-off, thereby improving flight safety.

The drawing shows a structural diagram for implementing the inventive method of protecting a turbocharger.

Block 1 is a differentiating block, the input of which receives a signal about the pressure value behind the compressor Р _к . In block 1, the first derivative P _k is calculated in time

с параметром

представляющим собой предельно допустимое значение параметра

при помпаже двигателя.Block 2 - a comparison block that compares the current value

with parameter

representing the maximum permissible parameter value

when surging the engine.

Block 3 is a comparison unit that compares the current value of the rotational speed n _vd with its threshold value

Logical block 4 operates according to the “AND NOT” scheme. With the simultaneous presence at the two inputs of block 4 of the signals coming from blocks 2 and 3, the output signal is blocked to turn off the fuel supply to the combustion chamber and to turn on the air bypass in the compressor.

The method is as follows.

поступает на вход блока 2, где осуществляется сравнение текущего значения

с пороговой величиной

At the input of block 1, a signal characterizes the pressure behind the compressor R _to . The output signal I ₁ from block 1, characterizing the value

arrives at the input of block 2, where the current value is compared

with threshold

с выхода блока 2 на вход блока 4 и на регистрирующее устройство поступает сигнал I₂, характеризующий состояние неустойчивой работы компрессора (сигнал “помпаж”).At

from the output of block 2 to the input of block 4 and to the recording device receives a signal I ₂ characterizing the state of unstable operation of the compressor (signal "surge").

При

сигнал на выходе блока 3 отсутствует (I₃=0) и не поступает на вход блока 4. Если одновременно с этим на вход блока 4 с выхода блока 2 поступает сигнал “помпаж” (I₃=0, I₂=1), то на выходе блока 4 формируется сигнал на отключение подачи топлива в камеру сгорания и на включение перепуска воздуха в компрессоре (I₄=1).Block 3, the input of which receives a signal about the value of n _vd , compares it with the value

At

there is no signal at the output of block 3 (I ₃ = 0) and does not go to the input of block 4. If at the same time the signal “surge” is received at the input of block 4 from the output of block 2 (I ₃ = 0, I ₂ = 1), then at the output of block 4, a signal is generated to turn off the fuel supply to the combustion chamber and to turn on the air bypass in the compressor (I ₄ = 1).

на выходе блока 3 формируется сигнал I₃=1, поступающий на вход блока 4.At

at the output of block 3, a signal I ₃ = 1 is generated, which is input to the input of block 4.

When signals I ₃ = 1 and I ₂ = 1 arrive at the input of block 4, the output of block 4 will not have a signal I ₄ (I ₄ = 0), which will block the shutdown of the fuel supply to the combustion chamber and the inclusion of air bypass in the compressor.

Sources of information

1. Automatic control and diagnostics of control systems of power plants of aircraft, Moscow, “Mechanical Engineering”, 1989, p. 102.

2. RF patent No. 2098668, F 04 D 27/02, 1997

3. RF patent No. 2187711, F 04 D 27/02, 2002

4. RF patent No. 2041399, F 04 D 27/02, 1991 - prototype.

Claims (1)

A method of protecting a turbocharger, including measuring the air pressure behind the compressor (P _k ), determining its rate of change

comparison with its threshold value

and generating a signal to turn off the fuel supply to the combustion chamber and enable air bypass in the compressor when the value is exceeded

characterized in that they additionally measure the rotational speed of the high pressure rotor n _vd , compare it with a threshold value

and in case

block the signal to turn off the fuel supply to the combustion chamber and the signal to turn on the air bypass in the compressor.