RU2376487C2 - Method of gas turbine engine protection - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed method comprises controlling fuel feed in emergent uncoupling of power (free) turbine transmission. Fuel feed control, up to complete outage of feed, is subject to relative motion of engine rotor and stator and performed exploiting the properties of magnetic induction engine rotor RPM pickups to register relative dynamic motion of engine rotor, stator and transmission caused by oscillatory processes in engine operation. Note here that the moment of transmission failure is revealed simultaneously by engine unlike rotor RPM pickups to generate fuel feed reduction signal. Moment of power turbine transmission failure is revealed using, additionally, rotor torque measurement system pressure pickups which are taken to make technical state control system pickups. Claimed method allows simplifying engine protection system by ruling out additional inductors and RPM pickups in power (free) turbine via using signals of standard pickups.

EFFECT: reliability and fast detection of transmission shaft disengagement.

1 cl, 3 dwg, 1 tbl

Description

The claimed technical solution relates to the control of gas turbine engines, especially aircraft. In particular, it relates to methods for protecting the engine during emergency disconnection of the transmission of its power (free) turbine by controlling the fuel supply of the engine.

More specifically, the claimed solution relates to methods and logical systems for automatically monitoring the signs of a transmission state using a signal and, in particular, a free turbine by providing and executing commands to influence the fuel supply function with the restriction of its parameters until it is completely stopped.

The rotational speed of the rotor parts of gas turbine engines reaches from tens to several hundred revolutions per second. Disconnecting the transmission of one or another rotor leads to unpredictable catastrophic engine failure. Figure 1 schematically shows the disengagement of the transmission 6 GTE 1.

When this happens:

- sudden braking of the front (to the point of disconnection of the transmission) fragment (Figure 1 ω1_P → 0, the rotation speed tends to 0),

- uncontrolled acceleration or uncontrolled promotion of the back (behind the place of disconnection of the transmission) fragment (Figure 1 ω1_3), when the rotational speed tends to the self-braking frequency if fuel continues to flow in the turbine engine 1).

The latter causes an unacceptable risk when centrifugal forces reach values that lead to the destruction of the rear fragment from the impact of its parts on the stator housing, and its destruction with the possible ejection of components and subsequent destruction of the remaining parts of the engine and the fuselage.

This whole process takes place in tenths of a second, i.e. much faster than the reaction of the aircraft crew, therefore, in the International Aviation Rules AP33 (paragraph 33.19 (C) and JAR-T850, the mandatory presence of an automatic engine protection system is stipulated.

Protection against sudden destruction of the rotors of such engines when the transmission is disconnected, especially aircraft, is extremely important.

So, from the description of French patent No. 2818691 (class IPC F02C 9/28, applicant SNECMA, No. 0016899 dated December 22, 2000), a technical solution is known for protecting a gas turbine engine when casting a shaft speed.

It contains an electric converter with an electronic link for detecting an excess of the permissible speed, in particular, a high-pressure turbine shaft.

Protection is carried out by applying a hydraulic signal of the electric converter to the fuel control valve in the engine control lever system. In turn, this signal is generated by electronic link data, which tracks the speed.

The principle of the known solution is largely based on the interaction of hydraulic units. In this technical solution, at a critical moment when the permissible shaft rotation speed is exceeded, when the hydraulics are triggered, its insufficiently fast action can be negatively manifested.

From the description of US patent No. 6176074 (CL IPC F02C 7/00, CL NCI US 60 / 39.03, claimed by P&W 01/05/1998), a method for controlling a gas turbine engine with a compressor and a turbine on a common shaft when cutting and disconnecting the latter is known. The known method provides for the cessation of fuel supply in response to a speed signal from one or more speed sensors, in particular, and the increment ratio thereof.

Moreover, the known method involves placing sensors near the first stage of the compressor and further downstream of the compressor.

Thus, the known method is based on monitoring changes in the braking speed of the front fragment of the transmission when it is disconnected.

Therefore, there is no direct measurement and the signal of the rotation frequency of the rear fragment of the transmission, which reduces the reliability of the obtained data.

In addition, when the transmission is disconnected, the probability of desensing the sensors installed in the gas-dynamic path is very high.

From the description of US patent No. 6293085 (CL IPC F02C 9/28, CL NCI 60/39.03, declared by P&W on 11/29/2000), as a development of the FADEC system, a method and apparatus for logistic control of sudden shaft disconnection in operating modes are known, for example, in a gas turbine engine with an internal shaft of a low pressure rotor and an external shaft of a high pressure rotor.

The device in the electronic unit uses on each of the shafts two sets of two types of sensors.

One set - shaft speed sensors at the inlet to the low pressure compressor and pressure sensors at the inlet to the combustion chamber. These sensors communicate with the first channel of the FADEC (Full Authority Digital Engine Control) system.

Another set - absolute pressure sensors at the outlet of the combustion chamber and speed sensors.

They are communicated with the second, backup, channel of the FADEC system.

The most well-known method offers the installation of speed sensors and inductors at different ends of the transmission of the power tubing to detect differences in the readings of these sensors in case of disconnection of the specified transmission (the so-called differential protection).

It is understood that if the shaft is destroyed and the turbine rotational speed increases uncontrollably, the logistic scheme provides an operational command to immediately cut off the fuel supply to the combustion chamber.

The engine is braked, which is supposed to prevent possible catastrophic consequences.

The technical solution according to US patent No. 6293085 needs to be improved because it does not allow direct control of the spin-off of a disconnected turbine. Experimental tests have shown that during compressor braking and turbine spinning, their speeds differ significantly. Depending on the place of disengagement (rupture) of the shaft, the inductor can almost instantly, i.e. Before generating the signal, hit the speed sensor housing.

In these cases, state information simply cannot appear, and this indicates a certain unreliability of the known solution.

Experience has also shown that receiving duplication to confirm the reliability of the sensor signal (see Fig. 3, items 76 and 86 of the patent description) can give different results not only in amplitude but also in sign, which will lead to an ambiguous reaction of the system.

However, it is this well-known technical solution that is selected as a prototype of the claimed one due to the proximity of the problem being solved, the commonality of the individual essential features and the possibility of its improvement.

The stator of a gas turbine engine is always the “receiver” of all oscillatory processes occurring in the engine. The main components of these processes, as a reaction, are reflected (to one degree or another) in the signals of all magnetic induction speed sensors, since they have the property of sensitive elements of relative displacements in the rotor-stator system. That is, the signals of the above sensors in general can be represented as

Dx, Hx - coefficients depending on the type of sensor, installation location, mode

engine operation, terms and conditions of use, etc.,

Z1, Z2 - the number of teeth of gears-inductors,

ω1 (t), ω2 (t) - instantaneous rotational speeds of the rotors of the turbocompressor and a free turbine,

ωg (t) are the instantaneous frequencies of rotation of the drive links.

This was taken into account by the authors of this technical solution in order to prevent serious damage or at least limit their localization on the engine housing.

The authors were faced with the task of creating a way to protect a gas turbine engine and a system for its implementation, which would allow to achieve a certain cumulative technical result, including several logically interconnected causal progressive technical results, namely ensuring:

- on the operating modes of the gas turbine engine reliability and speed of detection by time and place of disconnection of the transmission shaft,

- prompt supply of the rotor displacement signal relative to the stator with the simultaneous operational reaction of limiting or complete cessation of fuel supply with extraordinary signals of mutual displacements of the rotor and stator,

- while simplifying the system by eliminating additional inductors and speed sensors in the region of the (free) power turbine due to the use of signals from standardly equipped sensors.

The obligatory minimum of such standardly equipped sensors in the gas turbine engine parameter control system is given in the industry standard OST 1 00788-2000, section 6, pages 6 and 7.

In OST 1 00788-2000, the parameters of the technical condition of nodes with constant signal output, which are subject to mandatory monitoring by means of standardly equipped sensors, are marked, namely:

- the frequency ω1 of rotation of the rotor of a free turbine is a sensor of the frequency of rotation of a free turbine (DCHV1 - the designation adopted by the authors),

- frequency of rotation of the rotor of the turbocompressor ω2 - sensor of the frequency of rotation of the rotor of the turbocompressor (DCHV2 - designation adopted by the authors),

- pressure Rickm in the channel for measuring torque - pressure sensor from the composition of the torque meter on the output shaft (DDikm - the designation adopted by the authors).

The problem is solved in that in the known method of protecting a gas turbine engine by controlling the fuel supply and the system for its implementation, certain improvements are made.

So, in the known method of protecting a gas turbine engine when disconnecting the transmission of its power turbine in the process of engine operation, the pressure signals and rotor speeds are used, then:

- process these signals,

- according to the results of processing determine the technical condition of the controlled transmission and thereby affect the function of controlling the supply of fuel to the engine,

The improvement is as follows:

control of the fuel supply to the engine up to its complete cessation is carried out by using information on the oscillatory processes of the engine due to the properties of the magnetic induction speed sensors to additionally issue such a response of the stator as a receiver of all the mentioned processes in the engine, including the specified transmission.

In this case, the moment of violation of the integrity of the transmission is diagnosed in time by changing the specified stator reaction and at the same time provide a reduction until the fuel supply is cut off.

The method is carried out by connecting an additional link to the fuel supply control module of the protection algorithms (MA3 - the abbreviation adopted by the authors), which, based on the properties of standard magnetic induction speed sensors, is able to perceive vibrational processes occurring in the engine and determine the moment of transmission integrity violation , and, according to the situation, to limit the supply of fuel until its complete cessation

The claimed technical solution is illustrated by drawings, where:

- figure 1 shows schematically a gas turbine engine with conventionally shown front and rear fragments of its transmission in case of disengagement of the latter.

For the front fragment, the rotation frequency tends to 0, i.e. braking ω1_P → 0;

For the back fragment (behind the place of separation), i.e. uncontrolled acceleration ω1_3 → ω of _self-braking ;

- figure 2 shows a schematic diagram of the interaction of elements and systems of the power plant of the aircraft when using the proposed method of protection;

- figure 3 shows an enlarged diagram of the algorithm of the automatic protection module (MAZ-8, figure 2);

- figure 4 is an auxiliary table of the individual symbols shown in the previous drawings.

The proposed method of protecting a gas turbine engine, the implementation of which is shown on a specific example of a twin-shaft gas turbine engine with a free (power) turbine, is as follows.

The gas turbine engine 1 (see Fig. 1, 2) contains a stator 2, in which a rotor of a free turbine is installed together with a sensor 3 (DCHV1), as well as a rotor of a turbocompressor with a sensor 4 (DCHV2) and a pressure sensor 5 (Ddikm) in system 6 torque meter. As indicated earlier, these are standardly equipped standard sensors, conditionally combined in group 7 (see Figure 2) and an auxiliary notation table (Figure 4).

A group of 7 sensors generates and generates the corresponding signals, namely X1 (t), which is also the PO signal of the speed sensor of the free turbine, X2 (t), it is also the P1 signal of the turbocharger rotation sensor, and the signal Pcm (t) of the meter pressure sensor torque, he's P2. These signals are sent to the protection algorithms module 8 (in the diagram of FIG. 2 - MAZ), which is additionally introduced into the electronic control system 9 (in the diagram of FIG. 2 - ESA) of the engine.

In the electronic control system 9 (ESA), the rotation frequency ω1 of the rotor of the power (free) turbine is compared in the software module 10 with the limit value (in the diagram of Figure 2 - software N2).

In turn, the software module 10, at certain specified values of ω1 of the maximum speed of the power turbine rotor, gives a command to the actuator 12 (in the diagram of FIG. 2 - MI) of the metering pump in submodule 11 to limit the fuel supply from the tank to the engine 1. In case of exceeding the critical value of the limit speed ω1 of the rotational speed of the power turbine rotor, the electronic control system 9 (ESA) issues a command to the valve 13 for stopping the supply of working fuel (in the diagram of Figure 2 - PPRT) of the metering pump in submodule 11 and, therefore, to stop the fuel supply to the engine 1.

Module 8 (FIG. 2) of protection algorithms (MAZ) receives software, P1, and P2 signals from group 7 of the aforementioned standard sensors (FIG. 2) and performs their corresponding discretization. Subsequently, the discretized signals X1 (t), X2 (t), Rickm (t) (Figs. 1, 2) enter the pre-processing sub-module 14 in the time domain (POW), where they are converted into a certain type of amplitude-frequency characteristic (AFC) :

Ak, Bk, Ck - partition coefficients,

k is the number of splits of the original signals,

ψk (t) are the basis functions of the partition.

From POW submodule 14, the data arrives at submodule 15 (see FIG. 3), where relative coefficients are formed in controlled ranges of the form

[n-m, ... n-1, n, n + 1, ... n + j, ... n + l] ∈к,

- относительные коэффициенты разбиения в подконтрольных диапазонах.

- Relative partition coefficients in controlled ranges.

Relative indicators are used to evaluate changes in the controlled area of the frequency response corresponding to the zone of operating speeds of the controlled transmission and the zones of possible speeds when the specified transmission is destroyed. The data of the assessment of changes in the form of relative coefficients and numbers of the range of amplitude-frequency characteristics of the frequency response fall into the generalization and comparison schemes (SO&S) 16, 17 and 18.

In submodule 16 of the generalization and comparison scheme (SO&S), the stability of changes is checked. In case of detection of changes in the areas below and above the operating frequencies, in the modules 17 and 18, the number of the current zone is compared, where changes in critical zones are noted

As a result, a set of features is determined, which subsequently enter the submodule 19 of the decision-making scheme (DSS).

Certain combinations of features determine both the state of the measurement system and the state of transmission of the rotor of the power (free) turbine.

In the case of determining a significant gradient of the change in the rotor speed of the power turbine, MAZ 8 generates in PSS 19 (19.2) a PZ command (see Figure 2) for fuel restriction and transmits it via a digital data bus to ESA 9 for further execution by an actuator (IM ) 12 metering pump 11. If a disconnection of the transmission of the rotor of the power (free) turbine is detected, the submodule of the decision scheme SPR 19 (19.1) issues a command P4 to the fuel shut-off valve (ППРТ) 13 of the metering pump 11 to shut off the fuel supply to engine 1. When identifying PARTICULAR circumstances, it may be provided a function of fuel flow restriction PP with a smoother transition to the termination of the fuel supply, as shown in Figure 3 in the embodiments, solutions submodule decision logic 19 said SPR.

The conducted experimental work showed that the interval of data collection and the result of their processing can be in the range of 0.01 ... 0.03 milliseconds. This approach allows in practice to solve many problems of monitoring the technical condition and protection of gas turbine engines, especially aircraft.

Claims (2)

1. A method of protecting a gas turbine engine containing magnetic induction sensors in the systems for monitoring the technical condition and engine control, including a system for measuring the torque of the engine rotors, when, in violation of the integrity of the power turbine transmission, the signals from these sensors are used proportional to the pressure parameters and rotational speeds of the engine rotors, which evaluate the technical condition of the engine, including the aforementioned power turbine transmission, and determine they determine the moment of its violation with the subsequent effect on the function of controlling the fuel supply to the engine, characterized in that the fuel supply control, up to its complete cessation, is formed on the basis of the relative movements of the engine rotors and its stator due to the properties of magnetic induction sensors of the rotor speed of the engine reflect the relative dynamic movements of the stator and rotors of the engine, including the power turbine transmission as a result of oscillatory processes during its operation, and the moment Decisions of the integrity of the specified transmission are simultaneously diagnosed by the rotational speed sensors of opposite rotors of the engine and a decrease in fuel supply is formed, up to its complete cessation. 2. The method of protecting a gas turbine engine according to claim 1, characterized in that the moment of integrity violation of said transmission of a power turbine is diagnosed, additionally using pressure sensors in the rotor torque measuring system as sensors of technical condition monitoring systems.

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