WO2015033786A1

WO2015033786A1 - Fuel supply system for gas turbine engine

Info

Publication number: WO2015033786A1
Application number: PCT/JP2014/071841
Authority: WO
Inventors: 典子森岡; 直喜関
Original assignee: 株式会社Ihi
Priority date: 2013-09-09
Filing date: 2014-08-21
Publication date: 2015-03-12
Also published as: JP2015052315A

Abstract

A fuel supply system for a gas turbine engine is provided with: a confluence passage (19) connected to a combustion nozzle (11); a first pump (P1) for discharging fuel into the confluence passage (19); a first electric motor (M1) for driving the first pump (P1); a second pump (P2) for discharging fuel into the confluence passage (19) and having a greater capacity than the first pump (P1); a second electric motor (M2) for driving the second pump (P2); and a boost pump (13) which is connected to both the first pump (P1) and the second pump (P2), increases the pressure of fuel stored in a tank (T), and supplies the fuel to the suction side of both the first pump (P1) and the second pump (P2). The boost pump (13) is driven by the first electric motor (M1).

Description

Fuel supply system for gas turbine engines

The present invention relates to a fuel supply system that supplies fuel to a gas turbine engine.

Patent Document 1 discloses a fuel supply system for a gas turbine engine. The fuel supply system includes a positive displacement pump directly connected to the engine. The positive displacement pump is driven by the power of the engine, thereby supplying fuel to the combustion chamber.

Also, a boost pump is provided upstream of this positive displacement pump. This boost pump boosts the fuel stored in the tank and guides it to the positive displacement pump. As a result, the positive displacement pump can reliably discharge the fuel. This boost pump also uses an engine as a drive source, like the positive displacement pump. Therefore, when the engine is driven, both pumps are operated and fuel is supplied to the combustion chamber.

JP 2008-215352 A

According to the above fuel supply system, when the discharge amount from the positive displacement pump is small, such as when the engine is started, that is, when the engine shaft rotates at a low speed, the boost pump also operates at a low speed. Therefore, the boosting action by the boost pump becomes insufficient, and there is a possibility that fuel cannot be discharged normally from the positive displacement pump. In addition, when each pump is operating in the low rotation region, oil film formation on the sliding surface between the pump shaft and the bearing becomes insufficient, and the bearing may be worn or deteriorated.

An object of the present invention is to provide a fuel supply system for a gas turbine engine that can more reliably supply fuel in a low rotation region such as when the engine is started and can reduce wear and deterioration of each component. .

One aspect of the present invention is a fuel supply system for a gas turbine engine that supplies fuel to a combustion chamber of an engine, the fuel supply passage being connected to a combustion nozzle that supplies fuel to the combustion chamber, and a fuel supply passage. A first pump that discharges fuel into the combustion chamber, a first drive source that drives the first pump, and a fuel supply passage that discharges fuel into the combustion chamber, which has a larger capacity than the first pump. The second pump, a second drive source for driving the second pump, and the first pump and the second pump are connected to boost the fuel stored in the tank to the suction side of the first pump and the second pump. A boost pump to be supplied, the boost pump being driven by a first drive source.

Further, either one or both of the first drive source and the second drive source may be an electric motor.

According to the present invention, it is possible to more reliably supply fuel in a low rotation region such as when the engine is started, and to reduce wear and deterioration of each component.

FIG. 1 is a schematic cross-sectional view of a turbofan engine. FIG. 2 is a diagram illustrating a fuel supply system. FIG. 3 is a flowchart for explaining the control at the time of starting the turbofan engine. FIG. 4 is a flowchart for explaining over-rotation prevention control. FIG. 5 is a flowchart for explaining a modification of the overspeed prevention control.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

Here, after describing a schematic configuration of a turbofan engine that is a gas turbine engine, a fuel supply system for supplying fuel to a combustion chamber of the turbofan engine will be described.

FIG. 1 is a schematic cross-sectional view of a turbofan engine. As shown in this figure, the turbofan engine 1 includes an outer cowl 3a provided with a fan 2 and an inner cowl 3b located in the outer cowl 3a. The inner cowl 3 b includes a compressor 4 that compresses the intake air sucked by the fan 2, a combustion chamber 5 that burns the compressed air compressed by the compressor 4, and an exhaust gas generated in the combustion process of the combustion chamber 5. A high-pressure turbine 6a and a low-pressure turbine 6b that convert the jet power of the jet into rotational energy are provided.

Rotational energy converted by the high-pressure turbine 6a is transmitted to the rotor 8 of the compressor 4 through the shaft 7a, and the rotor 8 rotates. The compressor 4 is operated by the rotation of the rotor 8. The rotational energy converted by the low-pressure turbine 6b is transmitted to the fan 2 via the shaft 7b provided in the shaft 7a, and the fan 2 is activated.

The compressor 4 includes an annular flow path 9 formed by an interval between the inner cowl 3 b and the rotor 8. The annular flow path 9 is gradually narrowed from the upstream side where air is sucked toward the downstream side connected to the combustion chamber 5. The intake air sucked into the compressor 4 is gradually increased in pressure as it is led from the upstream side to the downstream side of the annular flow path 9.

As described above, the combustion chamber 5 is supplied with fuel from the combustion nozzle 11 in order to burn the compressed air whose pressure has been increased by the compressor 4. Below, the fuel supply system which supplies a fuel to the combustion chamber 5 is demonstrated.

FIG. 2 is a diagram illustrating the fuel supply system 10 in the present embodiment. The fuel tank T stores fuel. As shown in this figure, the suction side of the boost pump 13 is connected to the fuel tank T via the suction passage 12. The boost pump 13 is constituted by an impeller pump, and a supply passage 14 is connected to the discharge side thereof. Thereby, the fuel stored in the fuel tank T is boosted by the boost pump 13 and guided to the supply passage 14.

The first pump P1 and the second pump P2 are connected to the supply passage 14 in parallel. The first pump P1 is a gear pump. The capacity of the second pump P2 is larger than that of the first pump P1. More specifically, the suction passage of the first pump P1 and the suction side of the second pump P2 are connected to the supply passage 14, and the fuel boosted by the boost pump 13 is guided to both pumps P1 and P2. It is burned.

The first passage 15 is connected to the discharge side of the first pump P1, and the second passage 16 is connected to the discharge side of the second pump P2. These

passages

15 and 16 are provided with

check valves

17 and 18, respectively. Both the

passages

15 and 16 join a joining passage 19 connected to the combustion nozzle 11 on the downstream side of both

check valves

17 and 18. A pressurizing valve 20 is provided in the merge passage 19. The fuel discharged from the first pump P1 or the second pump P2 is pressurized to a set pressure or higher by the pressurizing valve 20 and guided to the combustion nozzle 11. The first passage 15, the second passage 16 and the merging passage 19 constitute a fuel supply passage.

A reflux passage 21 is connected to the junction passage 19. One end of the reflux passage 21 is connected to the merging passage 19 upstream of the pressurizing valve 20, and the other end is connected to the supply passage 14. The reflux passage 21 is provided with a first shut-off valve 22. The first shut-off valve 22 is an electromagnetic valve that communicates the junction passage 19 and the supply passage 14 or shuts off the communication. The first shut-off valve 22 is normally maintained in a closed state that blocks communication between the merging passage 19 and the supply passage 14, and is displaced from the closed state to the opened state only when energization is controlled. 19 communicates with the supply passage 14.

Further, a second shut-off valve 23 is provided between the pressurizing valve 20 and the combustion nozzle 11 in the merge passage 19. The second shut-off valve 23 is composed of an electromagnetic valve. The second shut-off valve 23 is normally maintained in an open state that allows the merge passage 19 and the combustion nozzle 11 to communicate with each other, and is displaced from the open state to the closed state only when energization is controlled. The communication with the nozzle 11 is blocked. A return passage 24 is connected to the second shutoff valve 23. When the second shutoff valve 23 is displaced to the closed state, the fuel guided to the merge passage 19 returns to the supply passage 14 via the return passage 24.

In the figure, reference numeral 25 denotes a differential pressure gauge for detecting the differential pressure before and after the pressurizing valve 20, and reference numeral 26 denotes a relief valve.

In the present embodiment, a first electric motor M1 is provided as a drive source for the first pump P1. A second electric motor M2 is provided as a drive source for the second pump P2. A boost pump 13 is connected to the output shaft of the first electric motor M1 coaxially with the first pump P1. That is, the first electric motor M1 functions as a drive source for the two pumps, the first pump P1 and the boost pump 13. By driving the first electric motor M1, both the boost pump 13 and the first pump P1 operate simultaneously.

The first electric motor M1 is controlled by the controller C1. The second electric motor M2 is controlled by the controller C2. General digital engine control (Full Authority Digital Engine Control, hereinafter referred to as “FADEC”) outputs control signals to both controllers C1 and C2. Various detection signals and operation signals related to the turbofan engine 1 including the differential pressure before and after the pressurization valve 20 detected by the differential pressure gauge 25 are input to the FADEC. The FADEC controls the electric motors M1 and M2 and the second shut-off valve 23 based on various input signals to control the supply flow rate to the combustion nozzle 11.

As shown in FIGS. 1 and 2, the fuel supply system 10 of this embodiment includes a rotational speed detection sensor 27 that detects the rotational speed of the shaft 7a in the turbofan engine 1. A detection signal detected by the rotation speed detection sensor 27 is input to an over speed limiter (hereinafter referred to as “OSL”). OSL is an electronic control system independent of FADEC. The OSL monitors whether or not the rotational speed of the shaft 7a exceeds a predetermined threshold value, and when it is determined that the shaft number exceeds the threshold value, the OSL controls the energization of the first shutoff valve 22 to displace it. At the same time, a control signal for shutting off the power supply of the second electric motor M2 is output to the controller C2, and control is performed to stop the driving of the second electric motor M2.

Next, the operation of the fuel supply system 10 having the above configuration will be described. FIG. 3 is a flowchart illustrating control at the time of starting the turbofan engine 1 by FADEC.

(Step S1) First, when an operation signal for starting the turbofan engine 1 is input, the FADEC outputs a signal for driving the first electric motor M1 to the controller C1.

(Step S2) Next, the FADEC monitors whether the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has reached a predetermined number or more.

(Step S3) If it is determined in step S2 that the rotational speed of the shaft 7a has reached a predetermined number or more, FADEC outputs a signal for driving the second electric motor M2.

As described above, when the turbofan engine 1 is started, first, the first electric motor M1 is driven, and the boost pump 13 and the first pump P1 operate simultaneously. The first pump P1 has a capacity that can secure a flow rate required at the time of starting the turbofan engine 1 during rated rotation. And the 1st electric motor M1 drives the 1st pump P1 from which the rated rotation speed of the 1st pump P1 is ensured from the time of the start of the turbofan engine 1. The boost pump 13 is designed so as to ensure a rotation speed capable of sufficiently boosting the fuel by driving the first electric motor M1 at this time.

Thus, when the turbofan engine 1 is started, the fuel sufficiently boosted by the boost pump 13 is guided to the suction side of the first pump P1, and the fuel is surely supplied from the first pump P1 to the first passage 15. Is supplied. On the other hand, the first pump P1 ensures a rated rotational speed. Therefore, a sufficient oil film is formed on the sliding surface between the pump shaft and the bearing, and there is no possibility that the bearing is worn or deteriorated. In other words, even when the turbofan engine 1 is started, the first pump P1 does not continuously operate in the low rotation region. That is, the trouble which arises by the action | operation of the pump in a low rotation area | region can be eliminated.

The second pump P2 operates when the rotational speed of the shaft 7a exceeds a predetermined number. At this time, the first electric motor M1 is still driven. Therefore, the fuel sufficiently boosted by the boost pump 13 is also guided to the suction side of the second pump P2, and the fuel can be reliably discharged from the second pump P2.

FADEC controls the supply flow rate based on various detection signals and operation signals. FADEC can perform optimal fuel supply by appropriately controlling the rotational speeds of both electric motors M1 and M2. Therefore, unlike the prior art, a metering valve for metering the fuel to be supplied to the combustion chamber 5 becomes unnecessary.

FIG. 4 is a flowchart for explaining over-rotation prevention control by OSL.

(Step S11)
When the turbofan engine 1 is started, the OSL constantly monitors whether or not the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has become a threshold value or more.

(Step S12)
In step S11, when it is determined that the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has become equal to or greater than the threshold value, the OSL controls the energization of the first shutoff valve 22 to open it.

(Step S13)
Next, the OSL outputs a signal for shutting off the power supply of the second electric motor M2 to the controller C2.

Thereby, when the turbofan engine 1 is in an overspeed state, the fuel guided to the merging passage 19 returns to the supply passage 14 via the recirculation passage 21. At the same time, the power source of the electric motor M2 is cut off and the second pump P2 stops operating. At this time, although the power supply of the second electric motor M2 is instantaneously cut, there is a slight operation delay until the first shutoff valve 22 is completely displaced into the open state.

However, until the first shut-off valve 22 is opened, a load is acting on the second pump P2 in the reverse rotation direction. Due to this load, the operation of the second pump P2 is stopped at the moment when the power supply of the second electric motor M2 is cut off, and the fuel supply from the second pump P2 having a large capacity is instantaneously stopped. As described above, the fuel supply can be stopped earlier by shutting off the power supply of the second electric motor M2 at the same time when the first shutoff valve 22 is opened.

Although detailed explanation is omitted, when the rotational speed of the shaft 7a detected by the rotational speed detection sensor 27 is equal to or greater than a threshold value, the second shutoff valve 23 is controlled to be closed by FADEC. Yes. In the present embodiment, when the turbofan engine 1 is in an overspeed state, only the second electric motor M2 is controlled to stop, and the first electric motor M1 is continuously driven. The power source of the first electric motor M1 may be shut off by FADEC or OSL. However, since the first pump P1 has a smaller capacity than the second pump P2, even if fuel is supplied from the first pump P1 during the slight operation delay time generated in the first shutoff valve 22, the second electric motor It does not diminish the effect of stopping the driving of the motor M2.

Further, in this embodiment, when the turbofan engine 1 is in an overspeed state, the OSL always cuts off the power supply of the second electric motor M2. However, for example, the OSL may perform the following control.

FIG. 5 is a flowchart for explaining a modification of the overspeed prevention control by OSL. Note that the processing by the OSL is repeatedly performed every predetermined time (for example, several milliseconds).

(Step S21)
When the turbofan engine 1 is started, the OSL determines whether or not the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has become equal to or higher than the first threshold value. If it is determined that the rotational speed is not equal to or greater than the first threshold, the OSL ends the process.

(Step S22)
If it is determined in step S21 that the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has become equal to or higher than the first threshold value, the OSL controls the energization of the first shutoff valve 22 to open it. .

(Step S23)
Next, the OSL determines whether or not the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 is equal to or higher than a second threshold value that is higher than the rotational speed set as the first threshold value. judge. As a result, when it is determined that the rotation speed of the shaft 7a input from the rotation speed detection sensor 27 is equal to or greater than the second threshold value, the process proceeds to step S24, and when it is determined that the rotation speed is not equal to or greater than the second threshold value. The process ends.

(Step S24)
If it is determined in step S23 that the rotational speed of the shaft 7a input from the rotational speed detection sensor 27 has become equal to or greater than the second threshold, the OSL shuts off the power supply of the second electric motor M2.

As described above, when the first threshold value and the second threshold value are set (defined) and the rotational speed of the shaft 7a is equal to or higher than the first threshold value, the first shut-off valve 22 is controlled to be opened. The power supply of the second electric motor M2 is cut off only when the second threshold value is exceeded. According to this process, when the urgency to stop the fuel supply is low, or when it is considered that the overspeed state is avoided and the normal control is restored in a relatively short time (the second threshold is exceeded and the second threshold is exceeded). In the case of less than the threshold), the driving of the second electric motor M2 is continued. Therefore, when the normal control is restored, the fuel supply can be restarted immediately. On the other hand, when the urgency is high, the power supply of the second electric motor M2 is cut off at the same time. That is, the fuel supply can be stopped instantaneously, and the overspeed state can be avoided earlier.

In the above-described embodiments and modifications, the flow rate may be controlled so that the fuel supply to the combustion nozzle 11 is completely shut off when the first shut-off valve 22 is open. Alternatively, a throttle may be formed in the open state of the first shutoff valve 22 to control the flow rate so as to ensure a constant flow rate for the combustion nozzle 11. For example, in an aircraft equipped with only one turbofan engine 1 described above, when priority is given to maintaining a constant thrust even when over-rotation is prevented, a constant flow rate can be secured even when the first shut-off valve 22 is open. Conceivable.

On the other hand, in an aircraft equipped with a plurality of turbofan engines 1 described above, it is conceivable that the fuel supply of some turbofan engines 1 is completely shut off when the first shutoff valve 22 is open. For example, in the above-described modification, the second threshold value is set to the rotation number that is determined as the over-rotation state, and the first threshold value is set to a rotation number that is smaller than the rotation number that is determined as the over-rotation state. A constant flow rate is ensured even when the first cutoff valve 22 is open. In this case, it is possible to prevent an overspeed state while maintaining a constant thrust.

In the above-described embodiment, the case where fuel is supplied to the turbofan engine has been described. However, the fuel supply system 10 is not limited to the turbofan engine but can be widely applied to gas turbine engines used for other purposes. It is.

In the above embodiment, the first electric motor M1 and the second electric motor M2 are used as drive sources for the first pump P1 and the second pump P2, respectively. However, the drive source of both pumps is not limited to an electric motor. Either one of the drive sources of both pumps P1 and P2 may be an electric motor. Moreover, both drive sources of both pumps P1 and P2 may be configured by a drive device other than the electric motor. Moreover, in the said embodiment, the boost pump 13 is comprised by the impeller pump, and all of the 1st pump P1 and the 2nd pump P2 are comprised by the gear pump. However, these pump types are not particularly limited to impeller pumps and gear pumps. In addition, these pumps may be volumetric or non-volumetric. In any case, two pumps for supplying fuel to the combustion nozzle and a boost pump for boosting and guiding the fuel to the suction side of both of these two pumps are provided, and the small capacity of the two pumps The pump and the boost pump may be configured to operate with the same drive source.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

The present invention can be used in a fuel supply system that supplies fuel to a gas turbine engine.

Claims

A fuel supply system for a gas turbine engine that supplies fuel to a combustion chamber of an engine,
A fuel supply passage connected to a combustion nozzle for supplying fuel to the combustion chamber;
A first pump for discharging fuel into the combustion chamber via the fuel supply passage;
A first drive source for driving the first pump;
Discharging the fuel into the combustion chamber via the fuel supply passage, a second pump having a larger capacity than the first pump;
A second drive source for driving the second pump;
A boost pump connected to the first pump and the second pump, and boosting the fuel stored in the tank and supplying the boosted fuel to the suction side of the first pump and the second pump;
The fuel supply system for a gas turbine engine, wherein the boost pump is driven by the first drive source.
The fuel supply system for a gas turbine engine according to claim 1, wherein one or both of the first drive source and the second drive source is an electric motor.