WO2017074225A1

WO2017074225A1 - Method of protecting a turbofan engine from uncontrolled low-pressure turbine acceleration

Info

Publication number: WO2017074225A1
Application number: PCT/RU2016/000716
Authority: WO
Inventors: Юрий Семенович САВЕНКОВ; Алексей Николаевич САЖЕНКОВ; Юрий Абрамович ТРУБНИКОВ; Юрий Иванович ТИМКИН; Сергей Владимирович БАЖИН
Original assignee: Акционерное общество "Объединенная двигателестроительная корпорация" (АО "ОДК")
Priority date: 2015-10-29
Filing date: 2016-10-19
Publication date: 2017-05-04
Also published as: RU2602644C1

Abstract

The invention relates to systems for automatically protecting gas turbine engines from uncontrolled acceleration of a turbine in the event of said turbine becoming decoupled from the compressor shaft. An initial slip value S_нaч and a current slip value S_тек are calculated for the low-pressure rotors. The value ΔS=S_тек-S_нач is calculated and compared with an initially established value А₁. The value Δn_Β=n_Β _нач - n_{в тек} is calculated and compared with an initially established value А₂. If the condition ΔS>A₁ and Δn_Β>Α₂ is simultaneously met, the supply of fuel to the engine is reduced or stopped completely, and a signal is given to open the air bleed valves in the compressor. The invention provides for the increased reliability of a system for protecting a turbofan engine from the uncontrolled acceleration of a low-pressure turbine.

Description

METHOD FOR PROTECTING A TWO-CIRCUIT TURBOREACTIVE ENGINE FROM LOW PRESSURE TURBINE SPIN

Technical field

The invention relates to the field of gas turbine engine manufacturing, and in particular to systems for the automatic protection of a gas turbine engine from spinning a turbine when it is disconnected from the compressor shaft.

State of the art

A known method of automatic protection of a gas turbine engine, the essence of which is that using the engine protection unit measure the speed r of the engine turbine, compare the measured value with a predetermined limit value, and when the speed r of the turbine r is higher than the predetermined value, a control signal is generated to stop the supply of fuel to the combustion chamber of a gas turbine engine (patent RU N ° 2493393, IPC F02C9 / 46, publ. 09/20/2013).

The disadvantage of this method is the lack of speed of the system, as well as the need to create and use an autonomous protection unit, which increases the cost of the engine and complicates its design, because such autonomous units are usually equipped with a separate set of speed sensors that are not used in a standard automatic control system or engine diagnostic system.

Known methods for the automatic protection of a gas turbine engine from promotion, in which to increase the speed of the system in terms of detecting the fact of turbine promotion, it is provided

dn

An additional definition of the first derivative is the frequency time rotation of the turbine rotor (patent US J \ ° 6176074, MFG F01D21 / 04, 21/06, F02C9 / 46).

The disadvantage of this method is that when

„Dn when using the speed parameter n and its derivative, false alarms of the system are possible, for example, due to short-term malfunctions of the speed measurement system n caused by an alternating contact in the wiring of the speed sensor. To eliminate this drawback in such protection systems, it is desirable to have two or more independent parameters, the failure of which at the same time due to electrical wiring failures should be assessed as an almost unbelievable event.

Closest to the claimed is a method of protecting a dual-circuit turbojet engine from the spin of a low pressure turbine, including measuring the speed of the turbocompressor, the speed of the low pressure turbine driving the fan into rotation, determining the technical condition of the engine based on the measured parameters, reducing or completely stopping fuel supply to the engine in case of detachment of the low pressure turbine from the fan shaft of the gas turbine engine (patent RU N ° 2376487, M F F02C9 / 46, publ. 20.12.2009). A system that implements the known method comprises magnetic induction speed sensors in the systems for monitoring the technical condition and engine control, as well as a pressure sensor for the torque measuring system. The moment of violation of the integrity of the transmission is diagnosed simultaneously by the speed sensors of the opposite rotors of the engine. Unlike rotor speed sensors are standardly equipped (standard) sensors of the speed of rotation of a free turbine and speed of a turbocompressor are used in the electronic engine control system. In this case, if the limit value of the rotor speed of the power turbine is exceeded, the protection system issues a command to the actuator of the pump regulator to reduce the fuel supply G _T to the engine. In case of exceeding the critical value of the limit speed of the power turbine, the electronic control system generates a command to completely stop the fuel supply to the engine (G _T = 0).

The disadvantage of this method, adopted as a prototype, is the need to use a special system for measuring torque, including pressure sensor. In general, this leads to a complication of the design of the engine and to a decrease in its reliability, as well as to an increase in the cost of the engine, including increase in operating costs. Also, the complexity of the algorithm for determining the fact of the disengagement of the shafts by changing the amplitude - frequency characteristics of the signals. When disconnecting the turbine shaft and the compressor shaft, damage to the speed sensor of the power turbine may occur, which leads to inoperability of the protection system. In addition, in the case of the use of magnetic induction sensors such as DTA, ДЧВ - 2500 during the spin-up and displacement of a free turbine (low-pressure turbine), the required mounting gap between the sensor and inductor changes, as a result of which a significant measurement error p occurs, which makes the anti-spin system also inoperative.

The technical result of the claimed invention is to increase the reliability of the determination of faults and increase the reliability of the protection system of a dual-circuit turbojet engine from the promotion of a low pressure turbine.

Disclosure of invention

The specified technical result is achieved in that in a method for protecting a double-circuit turbojet engine from spinning a low pressure turbine, including measuring a rotational speed of a turbocompressor, a rotational speed of a low pressure turbine driving a fan, determining a technical condition of an engine based on measured parameters, reducing or completely stopping supply fuel to the engine in case of detachment of the low pressure turbine from the fan shaft, according to the invention, for the technical condition of the engine additionally determines the initial S _Ha 4 ^and current S _TeK values of the slip of the rotors according to the formulas:

S _Ha4 - p _{vd nach} / p _{at nach} and S _TeK - n _{vd tech} / p _{at tech} , where

S _Ha4 - the amount of slip at the initial time before the change;

S _TeK is the amount of slip through the time interval At;

pvd nach ^_ turbocharger rotation speed before changing slip, rpm;

PV start - the rotation speed of the low pressure turbine before changing the slip, rpm

pvd tech - turbocharger speed through the time interval At, rpm;

p _{in tech} - the frequency of the low-pressure turbine after a time interval

At, rpm, calculate the value AS = S _xeK - S _Ha4 and compare it with Δη _Β = n _{at the beginning} - p _{in the} _{hake is} calculated by the initially set value of A and compared with the initially set value of A ₂ , in this case, if the condition is fulfilled at the same time, under which AS> Aj and Δη _Β > A ₂ , then carry out a reduction or complete cessation of fuel supply to the engine and a signal to open the air bypass valves in the compressor.

Implementation of the above operations of the claimed method allows to exclude measurement errors, false alarms of the engine protection system due to short-term malfunctions in the measurement of parameters and the occurrence of malfunctions of the protection system, which increases the reliability of the determination of malfunctions and the reliability of the protection system of a double-circuit turbojet engine from spinning a low pressure turbine. Also, the proposed method allows to simplify the algorithm for determining the separation of the turbine and compressor shafts, increase speed and reduce the cost of creating and operating a protection system by eliminating additional measuring devices.

The implementation of the invention

The claimed method can be implemented using a device whose structural diagram is shown in the drawing.

Using block 1, measure the rotational speed p _vd (p _{vd start} , p _{vd tech} ) of the high-pressure rotor (turbocharger). By means of block 2, the rotational speed p _in (p _{in the beginning} , p _{in the hake} ) of the low pressure turbine, which drives the engine fan, is measured. The sensors used to measure the rotational speed of the high-pressure rotor and low-pressure turbine are similar to those used in the prototype, and are standardly equipped (standard) sensors. However, in Unlike the prototype, to implement the claimed method, a sensor inductor for measuring the rotational speed of a low pressure turbine is located on the fan shaft, and the sensor itself is located near the fan blades. This arrangement eliminates the breakdown of the sensor during the destruction of the low pressure turbine.

By means of block 3, the slip S of both rotors is determined as the ratio of the rotational frequencies p _in / p _in , i.e. determine the value of the initial S _Ha4 value of the slip of the rotors at the time before the start of the change of slip and the current S _TeK value of the slip of the rotors over a fixed time interval At (At = 0.2 s) in accordance with the following formulas:

$ nach ^{- n} vd nach / ⁿ at nach ^and $ tech ^{- n} vd tech / ⁿ at tech? ^G TO

pvd nach - turbocharger rotation speed before changing the slip, rpm;

p _{in nach} - the frequency of rotation of the low-pressure turbine before the change in slip, rpm

pvd tech - turbocharger speed through the time interval At, rpm;

PV tech - the frequency of the low-pressure turbine through the time interval At, rpm

Using block 4, the first time derivative is determined with respect to time of the rotation speed parameter n _in low-pressure turbines (n _{in the beginning} ,

Pv tech) -

Blocks 5 and 6 are threshold devices.

Using block 5, the sliding parameter S is evaluated, i.e. calculate the difference between the current and initial values slip AS = S _TeK - S _Ha4 and compare with the first, initially given value Αι (Αι = 0.3). If AS> A] for a fixed time interval At (At = 0.2 s), then a logic signal “1” is generated at the output of block 5.

By means of block 6, an evaluation of the parameter is carried out, the value of Ap _in = n _{at the beginning} - n _{in the tech is} calculated. If the value of Ap _in the same fixed time interval At (At = 0.2 s) is greater than the second, initially set value of A ₂ (A ₂ = 500 rpm), then the second logical signal “1 ".

The values of Ai and A ₂ are determined from the condition that in case of disengagement of the low-pressure turbine with a fan (low-pressure compressor), the rotation speed of the spin of the turbine rotor will be less than the speed at which the turbine disks break.

If both the condition in which AS> A] and An _in> A _2, i.e. with the simultaneous presence of logical signals “1” at the two inputs of block 7, a block 8 command is generated at block 7. Block 8 is a fuel pump — a regulator that supplies fuel to the engine’s combustion chamber and controls the air bypass valves in the engine compressor. If the signal at the output of block 7 is observed for a fixed time At (At = 0.2 s), then the metering needle of the pump - controller moves at the maximum possible speed to the low gas position, i.e. in the direction of decreasing fuel consumption G _T into the engine (i.e., the fuel supply to the engine is reduced). If the signal at the output of block 7 is observed for a period of 0.4 s, then the fuel supply to the engine is reduced or completely stopped and a signal is sent to open the air bypass valves in the compressor: protection system generates a signal to completely stop the supply of fuel G _T to the engine combustion chamber (G _T = 0) and a signal to open the air bypass valves in the compressor. Opening the air bypass valves from the compressor to the external circuit of the engine at maximum mode leads to re-enrichment of the mixture and the extinction of the low-emission combustion chamber, thus turning off the fuel supply. In addition, when the bypass valves are opened, the power of the low-pressure turbine drops, which contributes to less damage when the turbine breaks down and localizes the failure.

Used to implement the inventive method, the electronic engine controller is a specialized electronic digital computer operating in real time and equipped with devices for interfacing with sensors, signaling devices, actuators and engine and aircraft systems.

Claims

Claim

A method of protecting a double-circuit turbojet engine from spinning a low-pressure turbine, including measuring the speed of the turbocompressor, the speed of the low-pressure turbine that drives the fan, determining the technical condition of the engine based on the measured parameters, reducing or completely cutting off the fuel supply to the engine in the event of a disconnected turbine low pressure from the fan shaft, characterized in that for determining the technical condition of the engine but starting S _Ha4 is determined and the current slip value S _TeK rotors by the formulas: S _Ha4 = p _{nach tm} / Ilb and early S _TeK - n _{tm tech} / n _{in tech,} wherein

S _Ha4 - the amount of slip at the initial time before the change;

S _xeK is the amount of slip through the time interval At;

pvd nach ~ turbocompressor rotation speed before change of sliding, rpm;

PV start ~ low-pressure turbine rotation speed before the slip change, rpm;

pvd tech ^- turbocharger speed through a time interval Δι, rpm;

n ^_ _in tech frequency low-pressure turbine after a time interval At, rev / min

calculate the value AS = S _TeK - S _Ha4 and compare it with the initially set value A _b calculate the value Δη _Β = n _{at the beginning} - p _{in the heck} and compare it with the initially set value A ₂ , in this case, if at the same time the condition is satisfied under which AS> Aj and Δη _Β > A ₂ , then the fuel supply to the engine is reduced or completely stopped and the signal for opening the air bypass valves in the compressor is applied.