RU2712103C1 - Control method of anti-icing system of bypass turbofan engine - Google Patents

Abstract

FIELD: aviation.SUBSTANCE: invention relates to anti-icing systems of aircrafts, particularly, to control method of anti-icing system of bypass turbofan engine (BTFE). Method of controlling an anti-icing system BTFE consists in that in flight using an engine-mounted sensor, measuring external parameters of flight conditions, on the change of which signals are generated to open the gate of the collector for extraction of hot air from the high-pressure compressor and to the sensors for measuring the rotation speed of the rotor of the fan and the rotor speed of the gas generator, determining the ratio of rotation frequencies and calculating the value of rotors sliding, by the change of which the icing nature and location is determined, then, signal is generated to electronic control unit of control device, which directs hot air flow to certain icing point via appropriate channel.EFFECT: development of control method for anti-icing system of BTFE, which provides higher efficiency of engine due to reduced amount of extracted working medium (hot air).1 cl, 4 dwg

Description

The invention relates to anti-icing systems of aircraft, in particular to a method for controlling the anti-icing system of a turbojet dual-circuit engine and can be used in aircraft engine control systems.

In flight conditions, constant monitoring of the state of a turbojet bypass engine (TRDD) and increasing the accuracy of its control are necessary, especially in the case of icing of the engine flow part due to liquid supercooled drops up to 20 microns in air, which represent “classical” icing, large ice crystals and a mixture of phases, including both large ice crystals and large supercooled water droplets ranging in size from 50 microns to 2 mm. Depending on the atmospheric conditions, icing of structural elements takes place in various places of the engine flow passage. In the case of “classical” icing, ice formation occurs due to small ice crystals and supercooled liquid water droplets present in the atmosphere, mainly at the engine inlet in the area of the fan, and when ice forms under conditions of large ice crystals and a mixture of phases, ice forms in retaining steps and at the entrance to the high pressure compressor of the gas generator. The formation of ice in the area of entry to the high-pressure compressor of the gas generator is due to the fact that large ice crystals entering the engine pass through the fan and retaining stages with air, partially melt, because the air temperature in the flow part of these units rises, resulting in of large ice crystals, a water shell forms, which upon collision with the design of the flow part creates an aqueous film on its surface, to which cristae adhering to the air adhere lly forming ice accretion.

The formation of ice crystals and supercooled water droplets of various sizes is associated with certain atmospheric conditions in which only the characteristic, special size of ice particles and supercooled drops is formed. In this regard, the simultaneous icing of various places in the engine flow passage with ice crystals and supercooled water drops, which have different sizes, is practically excluded.

The relevance of the problem of ensuring the turbojet engine operability in these conditions is explained by the need to prevent possible icing of the structural elements of the engine duct, and in the event of this process, its rapid diagnosis and subsequent elimination. For these purposes, the turbofan engine contains an anti-icing system, the inclusion of which according to a certain signal is carried out by a control system, the principle of which is to select the necessary amount of hot air from the engine and supply it to the internal cavities of the surfaces of the engine structure protected against icing.

A known method of controlling the anti-icing system of a turbojet dual-circuit engine, which consists in the fact that on the engine in flight conditions, according to the measured external parameters of the flight conditions, a signal is generated to turn on an electrical circuit consisting of a current source, a supply wire system and electric heating elements located in places of possible icing of the elements engine designs (US 6725645, 2004).

The disadvantage of the technical solution is the need to have on board the aircraft either an additional current source (batteries) or an electric generator for converting the mechanical energy taken from the engine shaft into electrical energy, which will inevitably lead to additional energy losses during its conversion, and to increase mass-dimensional indicators of the engine.

A known method of controlling the anti-icing system of a gas turbine engine (US 9683489, 2017), in which the anti-icing system of a gas turbine engine includes one or more sources of hot air, one or more sensors of icing, outdoor temperature and flight altitude, as well as a control device. The control device receives signals from one or more sensors, after which they supply hot air to a particular place in the engine, depending on the readings of the sensors. The disadvantages of this method include the low reliability of the readings of sensors, the operation of which under icing conditions can be disrupted due to the ice formed on them, which leads to a distortion of the data transmitted by them and may not provide the necessary supply of hot air to the ice formation in the engine structure, as well as erroneously to direct excess hot air to those structural elements that in this mode were not subjected to icing.

A known method of controlling the anti-icing system of the air intake of a gas turbine engine (RU 2666886, 2018), which consists in obtaining data on the external flight conditions using special sensors that record icing conditions that interact with the aircraft and propulsion systems that supply hot air to all possible icing places.

A disadvantage of the known technical solution is the fact that the supply of hot air drawn from the compressor is carried out at the same time to all structural elements of the engine that may be iced up, without first determining the specific place of icing. This leads to a decrease in engine efficiency due to irrationally increased selection of the working fluid (hot air).

The closest analogue to the claimed technical solution is a method of controlling the anti-icing system of a turbojet dual-circuit engine, which consists in the fact that in flight, using the sensor installed at the engine input, the external parameters of the flight conditions are measured, by changing which they form a signal for the control device to open, which opens the channel, by which the selection of hot air from the high-pressure compressor and its flow to all structural elements is subject to possible icing, while the supply of hot air itself is carried out in a pulsating mode (US 4831819, 1989).

A disadvantage of the known technical solution is that despite the supply of hot air in a pulsed mode to structural elements subject to icing, this supply is carried out to all possible places of icing at the same time, which requires an unreasonably increased consumption of bleed air and leads to inefficient use of the working fluid (hot air ) and, as a result, to reduce engine thrust and its efficiency.

The technical problem solved by the claimed invention is to eliminate the above drawback and to expand the arsenal of technical means, namely, to create a method for controlling the anti-icing system of a turbojet bypass engine.

The technical result provided by the invention consists in the implementation of its purpose, i.e. in creating a method for controlling the anti-icing system of a turbojet dual-circuit engine, which provides an increase in engine efficiency by reducing the amount of withdrawn working fluid (hot air).

The claimed technical result is achieved due to the fact that when implementing the method of controlling the anti-icing system of a turbojet dual-circuit engine in flight using the sensor installed at the engine inlet, the external parameters of the flight conditions are measured, by the change of which they generate signals to open the manifold damper to select hot air from the high-pressure compressor and to the sensors for measuring the rotor speed of the fan rotor and the rotor speed of the gas generator, determine the ratio and calculating the frequency of rotation of the rotors slip value, the change is judged on the nature and location of icing, then produce a signal to the electronic control unit regulating device which on the corresponding channel directs flow of hot air to a point of icing.

These essential features provide a solution to the technical problem with the achievement of the claimed technical result, since only the combination of essential features characterizing the invention allows to create a way to control the anti-icing system of a turbojet dual-circuit engine, which increases the efficiency of the engine by reducing the amount of working fluid (hot air) .

The proposed technical solution is based on the fact that when icing the input elements of the fan or the input elements of the gas generator, there is a significant deterioration in the operating conditions of the iced unit, which leads to a noticeable decrease in its efficiency and, ultimately, its frequency of rotation. In connection with this change of rotor slip value (see Theory turbojet engines / Ed SM Shlyakhtenko and VA Sosunova - Moscow:.. Engineering, 1979), that is, to change attitudes of the gas generator speed (n _gg ) and fan speed (n _in )

n _yy / n _in

You can judge the place of icing in the flow part of the engine. So, an increase in the slip value of the rotors indicates icing of the input elements of the fan, and a decrease indicates icing of the input elements of the gas generator.

The present invention is illustrated by a detailed description of the method of controlling the anti-icing system of a turbojet bypass engine with reference to figures 1-4, where

in FIG. 1 schematically shows a turbofan engine and anti-icing system;

in FIG. Figure 2 shows a graph of the decrease in specific fuel consumption on the amount of decrease in the consumption of hot air;

in FIG. Figure 3 shows a graph of the decrease in the temperature of the gas in front of the turbine as a function of the decrease in the flow rate of the extracted hot air;

in FIG. Figure 4 shows a graph of the increase in engine thrust versus the reduction in the flow rate of the drawn hot air.

In FIG. 1 the following notation is accepted:

1 - turbofan engine;

2 - fan;

3 - gas generator;

4 - fan turbine 2;

5 - output device;

6 - anti-icing system;

7 - collector;

8 - shutter;

9 - regulating device;

10 - electronic control unit of the regulating device 9;

11 - pipeline;

12 - channel for supplying hot air to the fan 2;

13 - channel for supplying hot air to the gas generator 3;

14 - icing sensor;

15 - sensor for measuring the frequency of rotation of the rotor of the fan 2;

16 - a sensor for measuring the rotational speed of the rotor of the gas generator 3;

17 - block calculating the magnitude of the slip of the rotors;

18 is a block for determining the change in the magnitude of the slip of the rotors.

In FIG. 1 is a diagram of a turbofan engine 1, including a fan 2, a gas generator 3, a turbine 4 of a fan 2 and an output device 5, an anti-icing system 6, consisting of a collector 7 for collecting hot air from a high pressure compressor (HPC) of a gas generator 3, a shutter 8, a control device 9 , the electronic control unit 10 controls the regulating device 9, the pipe 11 for supplying hot air from the collector 7 to the regulating device 9, the channel 12 for supplying hot air from the regulating device 9 to the input elements of the fan 2, channel 13 for supplying hot air from the control device 9 to the elements at the inlet of the gas generator 3, the icing sensor 14 installed at the inlet of the engine 1, as well as the sensor 15 for measuring the rotor speed of the fan 2 and the sensor 16 for measuring the rotor speed of the gas generator 3, calculation unit 17 the slip value of the rotors and the block 18 determine the change in the slip value of the rotors with time, connected to the electronic control unit 10 of the control device 9.

The control method of the anti-icing system 6 of a turbojet bypass engine 1 is implemented as follows. In flight, using the sensor 14 installed at the inlet of the engine 1, the external parameters of the flight conditions are measured. The sensor 14 detects the presence of probable icing conditions in the air (low temperature of the air, the presence of supercooled drops or ice crystals). By changing the external parameters of the flight conditions, they generate signals to open the shutter 8 of the collector 7 for taking hot air from the HPC of the gas generator 3 and to the sensors 15 and 16. Opening the shutter 8 of the collector 7 provides a supply of hot air from the HPC of the gas generator 3 through the pipe 11 to the control device 9. Using sensors 15 and 16 measure the rotational speed of the rotor of the fan 2 (n _in ) and the rotational speed of the rotor of the gas generator 3 (n _g ), respectively. The signals from the sensors 15 and 16 are received in the block 17 calculating the magnitude of the slip of the rotors, where they determine the ratio of rotational speeds and calculate the slip value of the rotors

n _yy / n _in .

The signal from block 17 enters block 18 determining the change in the amount of slip of the rotors. By changing the magnitude of the slip of the rotors in time, they judge the nature and place of icing. Then, a signal is generated from block 18 to an electronic control unit 10 of a regulating device 9, which directs the flow of hot air to a specific icing place through a corresponding channel.

Depending on the signal of the control unit 10 associated with the change in the slip value of the rotors, hot air is directed by the regulating device 9 into the channel 12 for supplying hot air to the input elements of the fan 2 or to the channel 13 for supplying air to the elements at the entrance to the gas generator 3. Thus, when decreasing the magnitude of the slip of the rotors, the control unit 10 gives the control device 9 a signal for supplying hot air through the channel 13, and when increasing, through the channel 12. Thus, the hot air in the required quantity flows precisely to that element design, is susceptible to icing during data operating conditions, thereby providing the engine performance in all types of icing its running part.

The proposed method of controlling the anti-icing system of the turbofan engine in case of icing of one of the two possible places of the engine flowing part, representing the engine inlet, including the fan, or the gas generator inlet, allows you to determine the ice formation and provide hot air to it when the hot air supply to other elements of the flow path that are not subject to icing in this mode, reduce the total air intake from the engine flow path and thereby increase s efficiency.

Estimates made for PD-14 type turbofan engines showed that under icing conditions with a decrease in the slip value of the rotors, hot air should be supplied only to the inlet elements of the gas generator and not to be supplied to the inlet elements of the fan. This will reduce the consumption of hot air taken from the HPC by approximately 1-1.2%, which, in turn, will allow to increase engine efficiency by 1.2-1.5%, while maintaining the required level of thrust, to reduce the gas temperature in front of the turbine is approximately 20-25 K, and at the maximum acceleration and climb mode, while maintaining the gas temperature in front of the turbine at the same level, increase engine thrust by approximately 2.5-3%.

With increasing slip of the rotors under icing conditions, hot air should be supplied only to the inlet elements of the fan and not to be supplied to the inlet elements of the gas generator. This will reduce the consumption of hot air taken from the HPC by approximately 0.5-0.6%, which, in turn, will allow to increase engine efficiency by 0.6-0.75% while cruising (while maintaining the necessary level of thrust) , reduce the gas temperature in front of the turbine by approximately 10-12 K, and at the maximum acceleration and climb mode while maintaining the gas temperature in front of the turbine at the same level, increase the engine thrust by approximately 1.25-1.5%.

на крейсерском режиме при постоянном уровне тягиIn FIG. Figures 2-4 for PD-14 turbofan engines show graphs of the dependence of the reduction in specific fuel consumption (δCr) and the gas temperature in front of the turbine

at cruising mode with a constant level of traction

(R = const)

and increase engine thrust (δR) in climb modes

)(on condition

)

the magnitude of the flow loss (δG _sel) withdrawn from the flow path of hot air compressor.

Thus, the technical solution provides an increase in engine efficiency by reducing the consumption of hot air taken from the engine duct and used by the de-icing system in a specific icing place, while unconditionally ensuring the engine is operable for all types of icing of its duct part.

Claims (1)

A control method for the anti-icing system of a turbojet dual-circuit engine, characterized in that in flight, using a sensor installed at the engine inlet, measure the external parameters of the flight conditions, by changing which they generate signals to open the manifold damper to select hot air from the high-pressure compressor and to speed sensors the rotor of the fan and the rotational speed of the rotor of the gas generator, determine the ratio of rotational speeds and calculate the slip value of the rotor s, by the change of which they judge the nature and place of icing, then they generate a signal to the electronic control unit of the regulating device, which directs the flow of hot air to a certain place of icing through the corresponding channel.

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