RU2054132C1 - Method and device for protecting turbo-compressor against surging - Google Patents

Abstract

FIELD: compressor engineering. SUBSTANCE: air pressure is measured downstream of a compressor, downstream of the first group of compressor stages and at the edge of a nozzle. When the rate of varying air pressure downstream of the first group of the compressor stages and at the edge of the nozzle as well as downstream of the compressor exceeds a threshold value, a signal about surging is generated. The device has pressure pickups downstream of the first group of compressor stages and at the edge of the nozzle, second and third differentiators, third threshold element, and second AND element. EFFECT: enhanced reliability. 3 cl, 2 dwg

Description

 The invention relates to engine building and can be used in protection systems for gas turbine engines (GTE) from surging.

 A known method of protecting a turbocharger from surge [1] In this method, the value of the control signal is generated from the measured signals of pressure and air temperature at the inlet and outlet of the compressor. Moreover, to eliminate surge, the effect is made on the air bypass window behind the compressor [1] The disadvantage of this method is the low reliability of surge recognition, due to the lack of simultaneous control of the rate of change of engine parameters and the “delayed” air pressure behind the compressor.

The closest technical solution is a method of protecting a turbocharger from surge [2]
The disadvantage of this method and device is the low reliability of surge recognition.

 The aim of the invention is to increase the reliability of recognition of surge.

 The goal is achieved by protecting the turbocharger from surge by measuring the air pressure behind the compressor and the air pressure behind the first group of compressor stages, in which the gas pressure on the jet nozzle medium is additionally measured and surge signals are generated if the threshold value is exceeded by the rate of change of air pressure behind the first group compressor stages and the rate of change of gas pressure on the medium of the jet nozzle, as well as in case of exceeding the threshold value of the delayed sign The rate of change of air pressure behind the compressor.

 The goal is achieved by a device that implements the above method, comprising an air pressure sensor behind the first group of compressor stages, an air pressure sensor behind the compressor and a first threshold device into which a gas pressure sensor on the jet nozzle medium and a second differentiator, a second threshold, are connected in series with it device, the first circuit And and the second circuit And, the output of which is connected to the fuel cut-off valve, a third differentiator and a series connected to it its threshold device and one-shot, the output of which is connected to the second input of the second And circuit, as well as the first differentiator, the input of which is connected to the output of the air pressure sensor behind the first group of compressor stages, and the output with the input of the first threshold device, the output of which is connected to the second input of the first circuit And, and the output of the air pressure sensor behind the compressor is connected to the input of the third differentiator.

 In FIG. 1 shows a block diagram of a device; in FIG. 2 a, b, in the schedule of the device.

It contains 1 air pressure sensor behind the first group of compressor stages P ₂ ^(I) ; 2 gas pressure sensor at the jet nozzle exit Р _с ; 3 air pressure sensor behind compressor P ₂ ; 4 first differentiator; 5 second differentiator; 6 third differentiator; 7 first threshold device; 8 second threshold device; 9 third threshold device; 10 first circuit AND; 11 one-shot; 12 second scheme I.

 The device is in a static state.

The air pressure sensor behind the first group of compressor stages P ₂ ^(I) 1 is connected in series with the first differentiator 4, the first threshold device 7, the first circuit I 10 and the second circuit I 12. The gas pressure sensor at the cut of the jet nozzle P _with 2 is connected in series with the second differentiator 5, a second threshold device 8 and a second input of the first aND circuit 10. The air pressure sensor P ₂ of the compressor 3 of the sequence is related to a third differentiator 6, the third threshold device 9, One-Shot timer 11 and the second aND circuit 12, whose output communication coupled to the fuel cutoff valve.

The method is as follows. The first differentiator 4 differentiates the values of the signal coming from the output of the air pressure sensor behind the first group of compressor stages P $\genfrac{}{}{0ex}{}{\text{(I)}}{\text{2}}$ . The second differentiator 5 differentiates the values of the signal coming from the output of the gas pressure sensor at the exit of the jet nozzle Р _с 2. The third differentiator 6 differentiates the values of the signal coming from the output of the gas pressure sensor behind the compressor Р ₂ 3. In the first threshold device 7, its threshold value is compared with a signal coming from the output of the first differentiator 4, when exceeded which a signal is output to the first circuit And 10.

 In the second threshold device 8, a comparison of its threshold value with a signal from the output of the second differentiator 5 is performed, upon exceeding which a signal is output to the first circuit I 10. In a third threshold device 9, its threshold value is compared with a signal from the output of the third differentiator 6 , exceeding which a signal is output to a single-shot 11. If signals appear on both inputs of the first And 10 circuit, then from the output of the last signal is fed to the input of the second And 12 circuit.

 The one-shot 11 determines the operating time of the signal from the output of the third threshold device 9. If signals appear on both inputs of the second And 12 circuit, then a signal is output from its output to the fuel cut-off valve to eliminate deep surge.

The surge recognition effect is to control the rate of change of parameters P ₂ , P $\genfrac{}{}{0ex}{}{\text{(I)}}{\text{2}}$ and P _c (dP ₂ / dt, dP $\genfrac{}{}{0ex}{}{\text{(I)}}{\text{2}}$ / dt and dP _c / dt) with a mandatory delay of the pressure signal P ₂ , since the change in the latter is more significant than the other parameters. This eliminates the possibility of false alarms (possible small pressure fluctuations, which always occur) in surge phenomena.

 The method and device are confirmed by the following theoretical considerations.

One of the most important parameters of an aircraft engine is the gas pressure at the jet nozzle exit Р _с , the air pressure behind the compressor Р ₂ and behind its first group of stages Р $\genfrac{}{}{0ex}{}{\text{(I)}}{\text{2}}$ (this takes into account one of the most important conclusions that in the process of the appearance and development of surging, the main role is played by the exchange of energy between groups of compressor stages).

At the same time, it is obvious that with surge P ₂ changes much faster than the other parameters, so it must be “delayed".

 The calculation of the rates of change of these parameters significantly reduces the likelihood of false positives about surges.

Thus, it is necessary to compare:
dP ₂ / dt ≥ C _{por. 1}
dP $\genfrac{}{}{0ex}{}{\text{(I)}}{\text{2}}$ / dt ≥ C _{por. 2}
dP ₂ / dt ≥ C _{por. 3}
From _{por 1} , from _{por 2} , from _{por 3} predetermined threshold values.

 Compared with the prototype, the method and device have a higher accuracy of surge recognition. The device does not require the creation of unique equipment; it can be performed on the basis of ordinary serial elements. An increase in the number of elements leads to a slight increase in the cost of the device. The economic effect of the use of the invention is achieved by increasing the resource of the power plant.

Claims (2)

 1. A method of protecting a turbocharger from surge by measuring the air pressure behind the compressor, determining the rate of change, comparing it with a threshold value, delaying the signal for a predetermined time and using it as a first protection parameter, measuring the second parameter of the turbocompressor, determining its rate of change and comparison with a threshold value, characterized in that, in order to increase reliability, measure the air pressure behind the first group of compressor stages and use it as the second parameters of a turbocharger, the gas pressure is measured at the exit of the nozzle is determined rate of change is compared with a threshold value signal is used as the third parameter and the turbocharger surging formed availability signal in case of simultaneous receipt of signals corresponding to the three parameters.  2. Device for protecting the turbocharger from surge, comprising an air pressure sensor behind the compressor, the output of which is connected through the first differentiator, the first threshold element and the delay element with the first input of the first element And, and the second differentiator and threshold element, characterized in that, for the purpose improving reliability, it contains an air pressure sensor behind the first group of compressor stages, a gas pressure sensor at the jet nozzle exit, a third differentiator and a threshold element and a second element And, and the sensors are yes Lenia connected through second and third differentiators and threshold element with inputs of the second element I.

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