RU2351807C2 - Method of protecting gas turbine engine against surge - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to aircraft engine production and can be incorporated with electronic hydro mechanical automatic gas turbine engine control systems. To identify the compressor surge state, this invention proposes to calculate additionally the surge criterion and compare it with the cut-in/cut-out settings selected for every gas turbine type experimentally. In case the said criterion exceeds the cut-in setting, the "SURGE" signal is generated. If the said criterion is smaller than the cutting-in setting, it is compared with cutting-off setting. Is the criterion exceeds the cutting-off setting, the "SURGE" signal is preserved. Is the criterion is smaller than the cutting-off setting, the "SURGE" signal is removed, cooling chamber is cut out and fuel feed to combustion chamber of gas turbine is resumed.

EFFECT: higher engine reliability and aircraft safety.

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Description

The invention relates to the field of aircraft engine manufacturing and can be used in electronic hydromechanical systems (ACS) for automatic control of gas turbine engines (GTE).

A known method of protecting a gas turbine engine against surge, implemented in a hydromechanical self-propelled guns with an electronic surge signaling device, [1]. The method consists in turning off the engine by a signal from a surge detector.

The disadvantage of this method is its low efficiency and the inability to use on single-engine aircraft (LA).

Closest to this invention in technical essence is a method of protecting a gas turbine engine, implemented, for example, in electronic hydromechanical self-propelled guns, [2].

The self-propelled gun contains a series-connected sensor unit (DB), which includes a surge indicator, an electronic regulator (ER), a fuel metering device (DT), and a stop valve (KO).

The method consists in the fact that with the help of the surge indicator, the start of compressor surge is determined, KOs are turned on and the fuel supply to the gas turbine combustion chamber is stopped for a predetermined time, depending on the characteristics of the gas turbine engine, after this time, the KOs are turned off and the fuel supply to the KS is resumed. GTE.

The disadvantage of this method is the following. The cessation of fuel supply to the COP usually provides the output of the engine compressor from surging. But the process of loss and restoration of gas-dynamic stability (GDU) reserves of a compressor strongly depends on the individual characteristics of a gas turbine engine. This is especially true of modern gas turbine engines (PS-90A, PS-90A1, PS-90A2), the gas generators of which are "squeezed" in the sense of gas-turbine engine reserves to ensure the economic performance of the engine. This leads to the fact that, for modern gas turbine engines, the proposed method of recovering fuel consumption (after a predetermined time) can aggravate the condition of the engine - if by the time the predetermined time has expired the engine has not yet surged, or cause repeated surging - if by the time the expiration of a predetermined time, the engine has not yet scored the necessary supply of GDU. This reduces the reliability of the engine and may lead to the need to turn it off. This reduces the safety of the aircraft (LA) and makes it almost impossible to use the known method to protect modern gas turbine engines.

The aim of the invention is to improve the quality of work of self-propelled guns in terms of protecting a gas turbine engine from surging and, as a result, improving the reliability of a gas turbine engine and the safety of aircraft.

The goal is achieved by the fact that in addition to identifying the compressor surge status, the surge criterion is calculated, the criterion is compared with the on and off settings determined for each type of gas turbine engine experimentally, if the criterion exceeds the inclusion setpoint, the "surge" signal is generated, and if the criterion is less than the inclusion setpoint, compare it with the shutdown setpoint, if the criterion is greater than the shutdown setpoint, save the "Surge" signal, if the criterion is less than the shutdown setpoint, remove the "Surge" signal, and only after that, they turn off the CO and resume the supply of fuel to the gas turbine engine.

The drawing shows a diagram of a device that implements the inventive method.

The device contains a series-connected database 1, which includes a surge indicator 2, ER 3, DT 4, KO 5, and DT is connected to the database 1, and KO 5 to the ER 3.

The device operates as follows. The electronic controller 2 by the signals of the sensors from block 1 according to known dependencies (see, for example, [2]) generates a control action on the diesel fuel 4, which carry out the required changes in fuel consumption in the engine CS. During normal operation, the TBG KO 5 is turned off.

When surge occurs, signaling device 2 generates a signal in ER 3. After receiving this signal, ER 3 generates a command to turn on KO 5. KO 5 stops the fuel supply to the KS. At the same time, by command of ER 3, DT 4 is set to the position corresponding to the fuel consumption in the MG mode.

After the surge is eliminated, the signal from the signaling device 2 is removed, the ER 3 turns off the CO 5. Through DT 4, the fuel consumption corresponding to the engine operating mode begins to flow to the CS.

The surge signaling device 2 is a calculator (processor, RAM, ROM) with input / output devices connected to the DB 1 and ER 2. The signaling device 2 operates as follows (all numerical values of the variables used are given for the PS-90A engine, but according to a known method, see ., for example, [3], they can be selected for any other engine according to its generalized characteristics).

Before calculating the criterion for surge, the conditions are checked, according to which the diagnosis of surge is turned off:

1. The presence / absence of a mark for disabling the surge diagnostic function (from ER 3).

2. The presence / absence of a turbocharger speed of more than 35% (at a lower frequency, the compression ratio is small).

3. The readiness of the buffer is checked, that is, its filling with standard values of pressure measurement behind the compressor, which are a continuous sequence.

Method for the diagnosis of surge based on digital filtering. This method is based on estimating the power of harmonics of the required frequency extracted from the air pressure signal behind the compressor, thus surge is diagnosed in the presence of air pressure fluctuations behind the compressor of a certain frequency and with a ratio of the amplitude of oscillations to the average pressure value greater than a certain limit value. Surge criteria are determined by the formula:

where ΔP _k is the amplitude of the air pressure fluctuations behind the compressor;

P _{to SR} - the average value of the measured pressure.

ΔР _{к is} defined as the power of harmonics of a certain frequency. Every process f (t) can be expanded in a Fourier series by the formula:

where ω ₀ is the fundamental angular frequency of the function (the smallest multiple harmonic);

a _n , b _n - the set of weights for each harmonic;

t is the time;

a ₀ is the constant component of the signal.

The coefficients can be calculated by the formulas:

The power of the signal thus represented, according to the Parseval theorem, is defined as

signal power - a value proportional to the square of the amplitude of the n-th harmonics of the signal, but we need to determine the relative amplitude of the signal frequency band, so we turn to the relative weight coefficients:

Thus, the criterion takes the following form:

where C is the criterion.

If we pass from the Fourier transform to the methods of optimal (quasi-optimal) digital filtering with a finite impulse response (FIR), then formula (6) will take the following form:

where a ₁ (n) and a ₂ (n) are the coefficients of the sine and cosine filters,

and ₃ (n) are the coefficients of the low-pass filter,

x (n) is the input sequence,

N is the order of the FIR filter.

Then, the criterion is compared with the operation setpoint (0.2), and in case of exceeding the signal “Surge” is issued, and if the criterion is less than the setpoint on, it is compared with the shutdown setpoint (0.15), and in case of exceeding the setpoint the signal “Surge” is removed.

Thus, it is possible to diagnose surging of the compressor of an engine by the internal motor parameter: air pressure behind the compressor by analyzing the dynamics of its change, which provides an increase in the reliability of assessing the state of the engine and the quality of the ACS and, as a result, increasing the reliability of the gas turbine engine and the safety of the aircraft.

LIST OF SOURCES OF INFORMATION

1. Keba I.V. "Flight operation of helicopter gas turbine engines." M., "Transport", 1976.

2. Cherkasov B.A. "Automation and regulation of the WFD." M., "Engineering", 1988.

3. Technical information No. 2001.06.29. "Method for the synthesis of surge criteria." Perm, OJSC STAR, 2001.

Claims (1)

A method of protecting a gas turbine engine (GTE) from surging, which consists in the fact that when a surge occurs, a stop valve (KO) is turned off and the fuel supply to the combustion chamber (CS) of the gas turbine is stopped, characterized in that in addition to identifying the compressor surging condition, the surging criterion is calculated, they compare the criterion with the on and off settings that are determined experimentally for each type of gas turbine engine; if the criterion exceeds the inclusion setpoint, the signal "Surge" is generated, and if the criterion is less than the inclusion setpoint, comparing They are shown with the shutdown setpoint, if the criterion greater than the shutdown setpoint saves the “Surge” signal, if the criterion is less than the shutdown setpoint, they remove the “Surge” signal, turn off the power switch and resume the fuel supply to the gas turbine engine.