JPS6045732A - Device for avoiding surge in gas turbine engine - Google Patents

Abstract

PURPOSE:To certainly avoid the surge of the compressor of a gas turbine, by detecting the surge to control the bled quantity of compressed air depending on the intensity of the surge. CONSTITUTION:The surge of the compressor 1 of a gas turbine is detected by a surge sensor 16. A bled air quantity necessary to avoid the surge is calculated by a control section 11 depending on the intensity of the surge. A bleeder valve 18 branched from a conduit 19 is driven on the basis of the calculated quantity to control the quantity of bleeding. The surge can thus be certainly avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surging avoidance device for a gas turbine engine, and is particularly improved to reliably prevent surging from occurring in an automobile gas turbine engine without impairing operating performance.

In a gas turbine engine, especially a two-shaft gas turbine engine, if the air flow rate passing through the compressor and the pressure ratio between the inlet and outlet of the compressor simultaneously fall within a certain range, noise and vibration may occur. It is known that surging can occur. When surging occurs, there is a risk of serious problems such as engine inoperability or damage. On the other hand, it is well known that the efficiency of an engine is highest near where surging occurs, and it is most important to avoid surging while operating it as close to surging as possible when designing a gas turbine engine control system. This is one of the major challenges.

Here, in order to avoid such surging, conventionally, as disclosed in Japanese Patent Application Laid-open No. 53-93212, Japanese Patent Publication No. 5B-704f1, etc., the fuel supply amount and variable nozzle opening degree have been adjusted depending on the operating conditions. Program control has been performed in which predetermined limits are applied to control quantities such as the following. However, such program control requires an unnecessarily large surging margin to avoid surging in any driving mode, resulting in poor acceleration performance and efficiency. There was a disadvantage. Furthermore, due to changes in the engine over time, clogging of the fluid passages, etc., the surging margin determined at the time of design may become insufficient, and surging may occur.

By the way, in gas turbine engines, air compressed by a compressor is sometimes used for auxiliary purposes other than driving a vehicle. For example, when supplying fuel to a combustor, compressed air can be used to perform desired fuel injection,
It cools turbine blades that are exposed to high temperatures, and if the compressor has room to spare, it may drive auxiliary equipment such as a pump and an air conditioner peripheral compressor.

Although the allowable amount of compressed air bleed is limited by the design of the gas turbine and the operating conditions used, it is known that the bleed of compressed air affects the operating line of the gas turbine.

FIG. 1 shows a characteristic curve of a compressor of a gas turbine, where the operating line of the gas turbine, e.g.
It is expressed as a curve W1 connecting the operating points at each rotation speed of the ii machine. Here, when the compressed air is extracted, the operating line moves to the high flow rate side and becomes, for example, a curve W2. In other words, when the amount of bleed air increases, the operating line moves away from the surging line, which reduces the risk of surging and makes driving safer. However, as it moves away from the surging line, efficiency decreases.

The operating line shown in FIG. 1 is an operating line in a steady state (steady operating line), and an operating line during acceleration/deceleration (transient operating line) draws a different curve from this.

FIG. 2 shows operating lines during such acceleration and deceleration. In FIG. 2, assuming that the steady operating line is AB, the operating lines during acceleration and deceleration draw curves such as S1 and S2, respectively.

When accelerating, the operating line always approaches the surging line, so if the surge margin is small or too much fuel is suddenly added, the j ■ turning line will move towards the surging line.
It intersects with the surging line, and surging occurs at that point, making it impossible to accelerate.

However, by removing the oil from compressed air, the second
Since the steady operating line in the figure also moves away from the surging line, it is expected that the operating line during acceleration will also move away from the surging line.

SUMMARY OF THE INVENTION An object of the present invention is to detect surging in a gas turbine engine and to extract compressed air according to the degree of surging, focusing on these conventional problems. To provide a surging avoidance device for a Takas turbine engine, which performs corrective control in a direction that avoids surging, thereby making it possible to reliably avoid surging in any operating mode.

The present invention will be described in detail below based on the drawings.

FIG. 3 shows an example of the overall configuration of a gas turbine engine to which the present invention is applied.

The gas turbine engine in this example is a two-shaft gas turbine engine with a heat exchanger, which is a type of regenerative gas turbine engine.

In FIG. 3, 1 is a compressor, and 2 is a pressure generator turbine installed coaxially with the compressor 1 relative to the gas generator axis IA. A power turbine 3 drives a transmission (not shown) via a reduction gear 4 and transmits power to the wheels. Reference numeral 5 designates an air filter, in which atmospheric air is taken in and purified, compressed by the compressor 1, and then heated through the heat exchanger 8 and delivered to the combustor 7. In the combustor 7,
The fuel supplied from the fuel supply device 8 is combusted by the air supplied via the heat exchanger 6 as described above. The combustion residue drives the compressor turbine 2 and further drives the power turbine 3 via the variable nozzle 9, and then passes through the heat exchanger 8.
The exhaust gas is cooled through the exhaust muffler 10 and discharged into the atmosphere as exhaust gas.

The control system that drives and controls each part configured in this way has a control unit 11 at its core, and includes a fuel supply device 8, a drive device 12 that drives the variable nozzle 8 of the power turbine, and an oil and gas system that adjusts the amount of compressed air extracted. It includes a valve 18 and a gas generator rotational speed (Ngg) detector 13. Power turbine rotation speed (Npt) detector 14. Compressor turbine inlet temperature sensor 15. The six oil/air valves 18, whose inputs are the surge sensor 16 and the accelerator opening sensor 17 that detects the depression angle of the accelerator pedal, are electromagnetic valves. Branches to adjust the amount of oil in the compressed air. The extracted compressed air may be used to operate an auxiliary device (not shown), or may simply be released to the atmosphere.

Here, the surge sensor 16 has a function of detecting the pressure on the inlet side or outlet side of the air to the compressor 1, or the differential pressure between the two, and when surging occurs or in a state close to surging, The occurrence of surging is detected by utilizing the fact that there is a large fluctuation in the pressure difference between the air inlet and outlet sides of the compressor l.

An example of the mounting position of the surge sensor 18 having such a configuration is shown in the fourth example.
As shown in the figure. In FIG. 4, 201 is the suction casing 2
02 and the shroud 203. 204 is a shaft, and 205 is a compressor impeller attached to the shaft 204. 20
6 is a vane type diffuser, this diffuser 20
A vaneless diffuser (air passage) 207 is formed between the impeller 205 and the impeller 205 . impeller 205
A small hole 208 is provided in the shroud 203 near the inlet of the shroud 203, and the surge sensor 16 is attached to the opening side of the small hole 208 facing the impeller 2Q5. In this case, surge sensor 1
6 detects the pressure (static pressure) near the inlet of the impeller 205.

Note that the surge sensor 16 can also be attached to the opening side of the small hole 208 provided in the shroud 203 near the outlet of the impeller 205 that faces the impeller 205 .

In this case, the surge sensor 16 detects the pressure (〃pressure) in the air passage 207 near the outlet of the impeller 205.

Note that the pressure sensor used as the surge sensor 16 is
Use a material that has a quick response of, for example, 1 to IQms and can withstand pressure shock when surging occurs.

Next, as for the basic control of the above-mentioned control system, the target rotational speed is determined mainly by the depression angle of the accelerator pedal, which is the required value of the rotational speed, the fuel supply amount corresponding to that target value is calculated, and the fuel injection Rotation control that rotates the gas generator by driving the fuel supply system including the valve, and performs feedback control (closed loop control) so that the rotation speed matches the target rotation speed mentioned above, and the rotation speed of the gas generator. In addition to temperature control, which performs feedback control of the turbine inlet temperature by opening and closing the variable nozzle 8 with respect to a predetermined target value of the turbine inlet temperature to achieve the highest efficiency according to the There are three types of control in total: surging avoidance control that detects surging in the turbine engine and corrects the amount of oil in the compressed air according to the detected degree of surging.

The device of the present invention performs surging avoidance control,
A schematic block diagram thereof is shown in FIG.

In FIG. 5, 31 is a surge determination section, 32 is a surge sensor abnormality diagnosis section, 33 is a calculation section, and 34 is a drive section for the bleed valve 18.

The surge determination section 31 receives the surging signal 18S from the surge sensor 16, determines the degree of surging, and sends the surging determination signal 31S to the calculation section 33.

The surge sensor abnormality diagnosis section 32 receives the surging signal +63 from the surge sensor 16 and the rotation speed signal 13S from the gas generator rotation speed detector 13 as input, and diagnoses whether the surge sensor 16 is normal or not. If it is not normal, a surge sensor abnormality diagnosis signal 32S is sent to the calculation unit 33.

The calculation unit 33 is supplied with a surge determination signal 31S and a surge sensor abnormality diagnosis signal 32S, and when the surge determination unit 31 determines that surging is occurring, it calculates the amount of oil required to avoid surging, and performs the calculation. The result is sent to the drive section 34 as a surge avoidance signal 33S.

Furthermore, when the surge sensor abnormality diagnosis section 32 diagnoses that the surge sensor IB is abnormal, the amount of oil necessary to avoid surging is constantly calculated, regardless of the surge determination signal 31S. and sends it to the drive section 34 as a surge avoidance signal 33S.

The drive unit 34 is supplied with the surge avoidance signal 33S as an input, converts it into a signal suitable for driving the oil/air valve 18, for example, a pulse width modulation signal, and uses this signal as the oil/air valve drive signal 34S to drive the oil/air valve 18. Send to.

FIG. 6 is a block diagram showing the configuration of FIG. 5 in detail.

In the surge determination unit 31, 111 is a filter;
Unnecessary frequency bands of the output signal 18s from the surge sensor 16 are attenuated. 112 is a packed ground noise level (BGL) generator, which is usually a filter 111
The output signal 111S is rectified and smoothed to produce a background noise level voltage (hereinafter referred to as BGL voltage) 112S.
(See Figure 8). In addition, a energization prohibition signal 116 from a monostable multi-pie break 116, which will be described later, is also provided.
A signal 1123 is output by cutting off the signal 111S from the filter 111 for a predetermined time after surging is determined by S.

The signal 111s in this BGL generator 112 is rectified.

An example of a circuit configuration for averaging is shown in FIG. Here,
When the analog switch SW is not determined to be surging by the energization prohibition signal 116S from the multi-by-break 118, it is closed, and the signal 111S sent from the filter 111 passes through this switch SW to the half-wave rectifier + (half-wave rectifier by WR). is passed through a low-pass filter LPF, and the averaged output is sent to an amplifier AMP.
A BGL signal 112S is formed by amplifying the signal.

Next, 113 is a comparator, which compares the output signal 1ixs from the filter 111 with the BGL voltage 112S, so that the output signal 111S from the filter 111 becomes the BGL voltage 112S.
When the surging detection signal 1 shown in FIG.
133 is output.

Here, the output signal 111S from the filter 111 changes depending on the degree of surging, and as shown in FIG.
For example, waveform 11 depending on the degree of strong, weak, or medium surging.
1S-1, lll5-2 and 111s-3. As a result, the surging detection signal 113S changes in pulse width and number depending on the degree of surging.
For example, if the signal 113S has a wide pulse width and a large number of pulses, this means that strong surging is occurring.

114 is an integrator that charges the surging detection signal 113S relatively quickly and discharges it slowly. 115 is a comparator having a hysteresis function, and the integrated signal 114S (see FIG. 8) from this integrator 114 is converted to a predetermined voltage VII.
When the integral signal 114S exceeds the predetermined voltage Vus, the surging determination signal 3 is generated as shown in FIG.
Outputs 1S.

The integral signal 114S has a voltage value corresponding to the degree of surging, and the comparator 115 removes the voltage caused by weak surging or noise that is not surging by comparing it with a predetermined voltage VIIs. As a result, surging of a predetermined intensity or higher is determined to be substantial surging, and surging determination can be performed extremely accurately and with high sensitivity.

116 is a monostable multi-pie break, which generates a pulse signal 118S (see FIG. 7 (E)) having a predetermined pulse width from the rising edge of the surging determination signal 31S, and for a predetermined period of time from the moment when surging is determined. B.G.
This signal 116S is output as a prohibition signal to the background noise level generating section 112 in order to prevent an excessive rise in the L voltage.

Next, in the sensor abnormality diagnosis section 32, 131 is a filter, which, like the filter of the surge determination section 31, attenuates unnecessary frequency bands from the output signal 1flS from the surge sensor 16. +32 is an averaging circuit that rectifies and averages the output signal 131s from the filter 131.

133 is a comparator which receives the average signal 1 from the average circuit 132.
32S with a predetermined reference voltage V133, the average signal 1
32S is below the reference voltage v133, a positive output signal 133S is generated.

134 is a frequency-voltage converter (FV converter) 2;
The detection signal from the aforementioned Ngg detector 13 is converted into a voltage signal proportional to the rotation speed, and the gas generator rotation speed (Ngg
) is sent to the comparator 135 as a signal 134S.

This comparator 135 generates a positive output signal 135S when the voltage of the aforementioned Ngg signal 134S exceeds a predetermined reference voltage V+ar.

13fi is an AND gate, which calculates the AND of each output signal 133S and 135S of the comparator 133 and the comparator 135, and generates a sensor abnormality diagnosis signal that becomes positive when both output signals 133S and 135S are positive. Generates 32S.

Here, under conditions where surging does not occur, a voltage value corresponding to a relatively small rotational speed of the gas generator at which the surge sensor 16 can generate a sufficiently large output signal is given as the value of the reference voltage V115-; The value of the reference voltage v133 is set in advance as a voltage value corresponding to a relatively small average signal obtained when the gas generator rotation speed is equal to or higher than the value of the reference voltage Vrsy.

As a result, if the output signal does not become large enough even though the surge sensor 18 has failed and surging has occurred, the sensor abnormality diagnosis signal 32S from the sensor abnormality diagnosis section 130 can detect the failure. can be detected. Moreover, it is effective not only for failures of the surge sensor 18 but also for defective wiring and poor contact of connectors.

Furthermore, based on the sensor abnormality diagnosis signal 32S, the abnormality of the surge sensor 16 can be displayed using a light emitting diode (not shown) or the like to notify the driver of the abnormality of the surge sensor.

Next, in the calculation unit 33, +21 is a monostable multipipe rake, and a surging pulse signal 1 having a predetermined pulse width from the rising edge of the surging determination signal 31S.
21S' (see FIG. 8) is generated.

122 is an integrator and a surging pulse signal 121S
is charged relatively quickly and discharged slowly to generate an integral signal 122.
S (see FIG. 7(G)). This integral signal 122S corresponds to the opening degree of the bleed valve 18 to avoid surging that has occurred or is about to occur. 123 is an analog switch, which outputs the integral signal 12 according to the surge sensor abnormality diagnosis signal 32S.
2S and the predetermined voltage V +2a are selected and output as the surge avoidance signal 33S. Here, the predetermined voltage 1
/125 is a voltage corresponding to a sufficient amount of oil to regularly prevent the occurrence of surging. The analog switch 123 selects the integral signal 122S when the surge sensor 16 is not abnormal, and selects the predetermined voltage V125 when the surge sensor is diagnosed as abnormal.

Next, in the drive unit 34, 141 is a pulse width modulator which pulse width modulates the surge avoidance signal 33S, which is a DC voltage corresponding to the opening command value of the oil/air valve 18, to perform pulse width modulation (PWM). A signal 141S is generated. A power amplifier 142 amplifies the power of the PWM signal 141S to generate an oil/air valve drive signal 34S that can drive the oil/air valve 18, which is a solenoid valve.

The bleed valve 18 is driven by the bleed valve drive signal 345, and when surging occurs, it immediately increases the amount of oil, and if surging does not occur thereafter, it gradually decreases the amount of oil to return to the original amount of oil. Return to Furthermore, when the surge sensor 16 is diagnosed as abnormal, it is driven to maintain a relatively large amount of bleed air that can constantly suppress the occurrence of surging.

As shown in Figure 2, surging is most likely to occur during acceleration, but when surging is detected and surging occurs, the amount of oil can be increased immediately, and gas turbine operation can be improved. The line can be moved away from the surging line. By moving the operating line away from the surging line, a surge margin is secured and surging disappears quickly. If surging does not occur after that, the oil amount is gradually returned to its original state, so the engine can continue to operate without excessively deteriorating efficiency.

In addition, as mentioned above, the surging detection sensitivity of the device of the present invention is sufficiently high, so it can detect not only strong surging, but also mild surging or the precursor to surging, so it is always in a state of no surging or a very weak surging. This enables efficient driving without sacrificing the driving feel.

It goes without saying that surging occurring in a state other than the acceleration process of the gas generator, for example in a steady state, can be controlled in exactly the same manner.

In addition, in this embodiment, the surge sensor abnormality diagnosis section 32 detects a failure of the surge sensor 16, so that even if the surge sensor 16 should fail, it will be detected and the oil in the compressed air will be detected. By increasing the amount, the occurrence of surging can be constantly suppressed, so there is no risk of damaging the engine.

In addition, in the above section, we explained the case between the outlet of the compressor and the heat exchanger as the place where compressed air is extracted, but between the outlet of the heat exchanger and the combustor, or between the combustor and the compressor turbine. It goes without saying that surging can be avoided and controlled in exactly the same way even if the air is bled at the pump.

As explained above, according to the present invention, surging in a gas turbine engine is detected, and when surging occurs, the amount of oil in the compressed air is increased relatively quickly, and then the original state is gradually restored. Since we have configured the system so that the surging returns to normal and perform closed-loop control regarding surging, it is possible to operate as close to the surging region as possible while avoiding surging, thereby preventing damage to the engine or impairing drivability. This enables efficient driving with excellent acceleration without any damage.

[Brief explanation of drawings]

Fig. 1 is a characteristic curve diagram of the compressor of a gas turbine, Fig. 2 is a characteristic curve diagram showing operating lines during acceleration and deceleration, Fig. 3 is a configuration diagram of a gas turbine engine to which the present invention is applied, and Fig. 4 is Third
Partial sectional view showing the mounting position of the illustrated surge sensor, No. 5
The figure is a block diagram showing an example of the surge avoidance control system shown in Fig. 3, Fig. 6 is a block diagram showing a specific example of the control system shown in Fig. 5, and Fig. 7 is the BGL generator shown in Fig. 6. FIG. 8 is a block diagram showing an example of the signal waveform diagram of each part shown in FIG. DESCRIPTION OF SYMBOLS 1...Compressor, IA...Gas generator shaft, 2...Compressor turbine, 3...Power turbine, 4...Reducer, 5...Air filter, 8...Heat exchanger , ? ...Combustor, 8.Fuel supply device, 8.Variable nozzle, 10.Exhaust muffler, 11.Control unit, 12.Drive device, 13.Gas generator rotation. Speed detector, 14... Power turbine rotation speed detector, 15... Compressor turbine inlet temperature detector, 16... Surge sensor, 17... Accelerator opening sensor, 18... Oil valve, 19... Conduit, 31... Surge determination section, 32... Abnormality diagnosis section, 33... Calculation section, 34... Drive section, 110... Surge determination section, 111... Filter, 112...Background noise level generator, 11
3... Comparator, 114... Integrator, 115... Comparator, 116... Monostable multi-octablator, 121...
Monostable multi-by-break, 122... Integrator, 123... Analog switch, 131... Filter, 132... Average circuit, 133... Comparator, 134... FV converter, 135...・Comparator, 136...AND gate, 141...Pulse amplification modulator, 142...Power amplifier, +BS...Surging signal, 122S...Surge avoidance signal, 135S...Surge sensor abnormality diagnosis signal. Patent applicant: Nissan Motor Co., Ltd. Agent: Yoshi Tani, patent attorney - Figure 1: Volume of 4th-age sludge

Claims (1)

[Claims] l) surge detection means for detecting the occurrence of surging in the compressor; surge determination means for determining the strength of the generated surging based on the output from the surge detection means; surging of a gas turbine engine, characterized in that it comprises an oil/air means for correcting the amount of oil in the oil/air means to avoid surging based on a determination output from the surge determining means; Avoidance device. 2. In the apparatus according to claim 1, the correction means promptly increases the amount of compressed air extracted when a determination output indicating that surging has occurred is supplied from the surge determination means. The surging avoidance device for a gas turbine engine is characterized in that the surging avoidance device for a gas turbine engine is characterized in that the amount of extracted air of compressed air is corrected so as to gradually reduce the amount of extracted air to the original amount again. 3) In the apparatus according to claim 1 or 2, the air extraction means is located between the compressor and the heat exchanger,
Or a surging avoidance device for a gas turbine engine, characterized in that it bleeds compressed air between a heat exchanger and a combustor, or combustion gas between a combustor and a compressor turbine. 4) surge detection means for detecting the occurrence of surging in the compressor; surge determination means for determining the strength of the generated surging based on the output from the surge detection means; , a correction means for correcting the amount of air extracted from the oil/air means to avoid surging based on a determination output from the surge determination means, an abnormality detection means for detecting an abnormality in the surge detection means, and the abnormality detection means. 1. A surging avoidance device for a gas turbine engine, comprising: a surge suppressing means for regularly suppressing the occurrence of surging when an abnormality in the surge detecting means is detected. 5) In the device according to claim 4, when an abnormality in the surge detection means is detected, the surge suppressing means constantly applies a larger amount of oil than when it is normal. Features: Gas turbine engine surging avoidance device. (Hereafter, margin)