CN215675302U

CN215675302U - Fuel control system

Info

Publication number: CN215675302U
Application number: CN202120492722.9U
Authority: CN
Inventors: 鄂亚佳; 邓向阳; 包志远; 宋国倩
Original assignee: AECC Commercial Aircraft Engine Co Ltd
Current assignee: AECC Commercial Aircraft Engine Co Ltd
Priority date: 2021-03-08
Filing date: 2021-03-08
Publication date: 2022-01-28
Anticipated expiration: 2031-03-08

Abstract

A fuel control system is used to suppress combustion oscillations. The device comprises a plurality of general nozzles, wherein each general nozzle comprises a pre-combustion stage nozzle and a main combustion stage nozzle; the system also comprises at least one enrichment nozzle, a pre-combustion stage circumferential controller and a main combustion stage circumferential controller, wherein the enrichment nozzle also comprises a pre-combustion stage nozzle and a main combustion stage nozzle; the pre-combustion stage circumferential controller is connected with the pre-combustion stage nozzles of the plurality of general nozzles through a general pre-combustion stage oil path and is also connected with the pre-combustion stage nozzles of the at least one enrichment nozzle through an enrichment pre-combustion stage oil path and is used for adjusting the fuel distribution proportion of the pre-combustion stage nozzles of the general nozzles and the enrichment nozzle; the main combustion stage circumferential controller is connected with the main combustion stage nozzles of the plurality of general nozzles through a general main combustion stage oil way and is also respectively connected with the main combustion stage nozzles of the at least one enrichment nozzle through an enrichment main combustion stage oil way, and the main combustion stage circumferential controller is used for adjusting the fuel oil distribution proportion of the main combustion stage nozzles of the general nozzles and the enrichment nozzle.

Description

Fuel control system

Technical Field

The utility model relates to a fuel control system of a combustion chamber.

Background

As atmospheric environmental concerns become more and more of a concern worldwide, the requirements for aircraft engine pollutant emissions are also becoming more and more stringent. The market demand of the next generation of aeroengine products shows that the emission of nitrogen oxides (NOx) is further reduced by about 45 to 60 percent compared with the CAEP6 regulated by the current International Civil Aviation Organization (ICAO). The adoption of the central staged lean oil combustion chamber can effectively reduce the emission of NOx. The combustion chamber uses a graded nozzle, only the pre-combustion grade nozzle supplies oil in a small state, and the main combustion grade nozzle and the pre-combustion grade nozzle supply oil together in a large state. However, such a combustion method is prone to the risk of combustion oscillations, i.e. pressure pulsations occurring during operation at a certain frequency outside the acceptable range, which, once they occur, may cause engine performance degradation and even structural damage.

Oscillatory combustion is an inherent feature of center-staged lean combustion, which is a phenomenon of coupling of combustion heat release fluctuations with engine hardware acoustic modes. In view of safety considerations, the usual approach requires more fuel to be distributed to the pre-combustion stage, enhancing relatively stable diffusion flame combustion to attenuate combustion oscillations. However, this conventional method of enriching the pre-combustion stage degrades the temperature distribution at the combustor exit, affects turbine life, while high temperatures may compromise combustor hardware and expose it to cooling risks, and too rich diffusion combustion may also cause a dramatic increase in pollutant emissions in a short period of time, degrading combustor emissions performance.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to provide a fuel control system for suppressing combustion oscillations.

The fuel control system comprises a plurality of general nozzles, wherein each general nozzle comprises a pre-combustion stage nozzle orifice and a main combustion stage nozzle orifice; the system also comprises at least one enrichment nozzle, a pre-combustion stage circumferential controller and a main combustion stage circumferential controller, wherein the enrichment nozzle also comprises a pre-combustion stage nozzle and a main combustion stage nozzle; the pre-combustion stage circumferential controller is connected with the pre-combustion stage nozzles of the plurality of general nozzles through a general pre-combustion stage oil path and is also connected with the pre-combustion stage nozzles of the at least one enrichment nozzle through an enrichment pre-combustion stage oil path and is used for adjusting the fuel distribution proportion of the pre-combustion stage nozzles of the general nozzles and the enrichment nozzle; the main combustion stage circumferential controller is connected with the main combustion stage nozzles of the plurality of general nozzles through a general main combustion stage oil way and is also respectively connected with the main combustion stage nozzles of the at least one enrichment nozzle through an enrichment main combustion stage oil way, and the main combustion stage circumferential controller is used for adjusting the fuel oil distribution proportion of the main combustion stage nozzles of the general nozzles and the enrichment nozzle.

In one embodiment, the fuel control system further comprises a fuel central grading control unit, which is in oil-way connection with the pre-combustion stage circumferential enrichment controller and the main combustion stage circumferential enrichment controller respectively and is used for adjusting the fuel flow distribution proportion of the pre-combustion stage circumferential controller and the main combustion stage circumferential controller.

In one embodiment, the fuel control system further comprises an engine electronic control unit for receiving signals and outputting control commands to the pre-combustion stage circumferential enrichment controller or/and the main combustion stage circumferential enrichment controller or/and the fuel center staging control unit.

In one embodiment, the fuel control system has a general operating mode in which the fuel distribution ratio of the pilot stage circumferential controller to the main stage circumferential controller is set to: the fuel flow rate of the precombustion stage of the single general nozzle is consistent with the fuel flow rate of the precombustion stage of the single enrichment nozzle, and the fuel flow rate of the main fuel stage of the single general nozzle is consistent with the fuel flow rate of the main fuel stage of the single enrichment nozzle; in the enrichment working mode, the fuel distribution proportion of the pre-combustion stage circumferential controller and the main combustion stage circumferential controller is set as follows: the fuel flow of the precombustion stage of the single general nozzle is multiple times of the fuel flow of the precombustion stage of the single enrichment nozzle, and the fuel flow of the main fuel stage of the single general nozzle is inconsistent with the fuel flow of the main fuel stage of the single enrichment nozzle, and the fuel flow of the single general nozzle is equal to the fuel flow of the single enrichment nozzle.

In an embodiment, the fuel control system further has a small-state operation mode in which the pre-stage circumferential controller is arranged to supply oil only to the pre-stage nozzle orifices of the general nozzle to increase the fuel flow rate of the pre-stage nozzle orifices of the general nozzle.

In one embodiment, the fuel control system further comprises a sensor in signal connection with the engine electronic control unit for detecting a combustion oscillation signal.

When oscillatory combustion occurs, dynamic pressure inside the combustion chamber fluctuates, the pre-combustion stage circumferential enrichment controller and the main combustion stage circumferential enrichment controller respectively act, for example, the flow of pre-combustion stage fuel oil of the enrichment nozzle is increased (or reduced), and the flow of main combustion stage fuel oil of the enrichment nozzle is reduced, so that the overall combustion heat release fluctuation characteristic of the combustion chamber is changed, the flame heat release fluctuation deviates from the acoustic mode of the working environment, the coupling between the two is broken, and the effect of inhibiting combustion oscillation is achieved.

Drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a structural cross-sectional view of a center staged combustor;

FIG. 2 is a cross-sectional view of a fuel injector;

FIG. 3 is a front view of the fuel injector;

FIG. 4 is a block diagram of a fuel control system;

FIG. 5 is a control logic diagram of the fuel control system.

Detailed Description

As shown in fig. 1 and 2, the combustor 3 includes a diffuser 300, a combustor outer casing 302, a combustor inner casing 304, a liner outer ring 306, a liner inner ring 308, and a fuel nozzle 310, and is connected to a high-pressure turbine vane 340. The incoming air of the high-pressure compressor enters the combustion chamber 3 after being subjected to speed reduction and pressure expansion through the diffuser 300. The combustor casing is located downstream of the diffuser 300 in the flow direction of the incoming air, and includes a combustor outer casing 302 and a combustor inner casing 304, and the combustor outer casing 302 and the combustor inner casing 304 constitute the outer contour of the combustion chamber 3 and are connected to the front and rear high-pressure compressors and high-pressure turbines. The liner is located downstream of the diffuser 300 in the direction of the incoming air flow and is located in the space enclosed by the combustor outer casing 302 and the combustor inner casing 304, which includes a liner outer ring 306 and a liner inner ring 308. The plurality of fuel nozzles 310 are uniformly arranged along the circumferential direction of the single-ring cavity structure of the combustion chamber 3, in one embodiment, the number of the fuel nozzles is 10-60, and air incoming flow enters the flame tube through the fuel nozzles 310 after passing through the diffuser 300. The individual fuel nozzles 310 are of a central hierarchical structure. The fuel nozzle 310 includes a main stage 316, a pre-stage 318, a main stage oil passage 312, and a pre-stage oil passage 314. The main combustion stage 316 is arranged coaxially with the pre-combustion stage 318, the pre-combustion stage 318 being in the center, the main combustion stage 316 being arranged at the periphery of the pre-combustion stage 318. The main combustion stage oil path 312 is connected with the main combustion stage oil collecting annular cavity 320, fuel oil in the main combustion stage oil collecting annular cavity 320 is injected to the main combustion stage premixing and pre-evaporating channel through a plurality of main combustion stage nozzles 350, main combustion stage direct spray is formed in the main combustion stage combustion area 324, the fuel oil is crushed and atomized under the shearing action of two rotational flows of the main combustion stage outer side cyclone 328 and the main combustion stage inner side cyclone 330 to form main combustion stage pneumatic atomized oil mist, and the main combustion stage pneumatic atomized oil mist is mixed with air to form a uniform oil-gas mixture, so that premixing and pre-evaporating combustion is realized. The pre-combustion stage oil passage 314 is connected with the pre-combustion stage nozzle 321, the pre-combustion stage nozzle 321 is approximately positioned at the radial center of the pre-combustion stage 318, pre-combustion stage fuel oil is sprayed out from the pre-combustion stage nozzle 321 of the pre-combustion stage 318, pre-combustion stage conical spray is formed in the pre-combustion stage combustion area 326, and pre-combustion stage flame is formed at the downstream after the pre-combustion stage conical spray is mixed with the swirling air of the pre-combustion stage inner swirler 332 and the pre-combustion stage outer swirler 334, so that diffusion combustion or semi-premixed semi-diffusion combustion is realized.

The above combustion chamber 3 having the center staged combustion structure has been disclosed in patent CN 110657455A.

Referring to fig. 4, a fuel control system for a center-staged combustion chamber 3 includes an engine electronic control unit 1, a sensor 6, a fuel center-staged control unit 2, a pre-combustion stage circumferential controller 4, and a main-combustion stage circumferential controller 5. The fuel control system also includes N generic nozzles A, each generic nozzle A including a pre-combustion stage nozzle 321 and a main combustion stage nozzle 350. The fuel control system also includes M enrichment nozzles B that also include pre-combustion stage jets 321 and main combustion stage jets 350. In one embodiment, nozzle a and enrichment nozzle B are generally of the same configuration. In other embodiments, the general nozzle A and the enrichment nozzle B may be configured differently, such as differing numbers of orifices, orifice diameters, fuel passage lengths, and so forth. M is not less than 1, and the specific number of M and N is determined according to the specific combustion chamber model.

The fuel center grading control unit 2 is of a mechanical hydraulic structure and is arranged on the upstream of the pre-combustion stage fuel main pipe P and the main combustion stage fuel main pipe M. The fuel oil is divided into two paths from the fuel tank 7 to the fuel oil central grading control unit 2 through the oil pump 8, passes through the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 respectively, and is divided into four oil paths PA, PB, MA and MB. As shown in FIGS. 2 and 3, each fuel nozzle 310 has two types of ports: a pre-combustion stage jet 321 and a main combustion stage jet 350. As shown in fig. 4, the pre-combustion stage nozzle 321 of the general nozzle a is connected with the general pre-combustion stage oil passage PA, and the main combustion stage nozzle 350 is connected with the general main combustion stage oil passage MA; the pre-combustion stage nozzle 321 of the enrichment nozzle B is in butt joint with an enrichment pre-combustion stage oil way PB, and the main combustion stage nozzle 350 is in butt joint with an enrichment main combustion stage oil way MB.

The central staged combustion chamber 3 has N + M fuel nozzles 310 as shown in fig. 2 and 3, and each fuel nozzle 310 has a completely identical structure. The type, number, and number of fuel jets for each fuel nozzle 310 are not limited to those shown. FIG. 2 illustrates the pre-stage and

main stage jets

321, 350 of one fuel nozzle 310, as well as the pre-stage and main

stage combustion zones

326, 324. By using the fuel control system shown in fig. 4, it is possible to realize the fuel flow rate difference between the pre-combustion stage nozzle hole 321 of the general nozzle a and the pre-combustion stage nozzle hole 321 of the enrichment nozzle B, and simultaneously, the fuel flow rate difference between the main combustion stage nozzle hole 350 of the general nozzle a and the main combustion stage nozzle hole 350 of the enrichment nozzle B.

The operating principle of the fuel control system, including hardware, signal transmission and fuel supply paths, is shown in fig. 4, where the solid line is the fuel supply path and the dashed line is the signal transmission path. The sensor 6 is in signal connection with the engine electronic control unit 1 for detecting a combustion oscillation signal. The engine electronic control unit 1 is used for receiving signals of the sensor 6 and outputting control commands to any one of the pre-combustion stage circumferential controller 4, the main combustion stage circumferential controller 5 and the fuel center grading control unit 2, or any two of the two or three of the two.

The fuel central grading control unit 2 is actuated after receiving the instruction of the engine electronic control unit 1, and changes the fuel flow distribution ratio of the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 by changing the flow area.

The precombustion stage circumferential controller 4 is connected with a general precombustion stage oil path PA and an enrichment precombustion stage oil path PB, and the precombustion stage circumferential controller 4 is connected with the precombustion stage jet ports 321 of N general nozzles A through the general precombustion stage oil path PA and is connected with the precombustion stage jet ports 321 of M enrichment precombustion stage oil paths PB and M enrichment nozzles B. The pre-combustion stage circumferential controller 4 is actuated upon receiving a command from the engine ecu 1 to change the fuel distribution ratio of the normal nozzle a and the enrichment nozzle B by changing the flow area.

The main combustion stage circumferential controller 5 is connected to the general main combustion stage oil path MA and the enrichment main combustion stage oil path MB, and the main combustion stage circumferential controller 5 is connected to the main combustion stage nozzles 350 of the N general nozzles a through the general main combustion stage oil path MA and is connected to the main combustion stage nozzles 350 of the M enrichment nozzles B through the enrichment main combustion stage oil path MB. The main stage circumferential controller 5 is actuated upon receiving a command from the engine ecu 1 to change the fuel distribution ratio of the ordinary nozzle a and the enrichment nozzle B by changing the flow area.

The fuel control system has two working modes: a general operating mode and an enrichment operating mode. In a general working mode, the fuel distribution proportion of the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 is set as follows: the pre-stage fuel flow of the single generic nozzle a coincides with the pre-stage fuel flow of the single enrichment nozzle B, and the main stage fuel flow of the single generic nozzle a coincides with the main stage fuel flow of the single enrichment nozzle B. In the enrichment working mode, the fuel distribution proportion of the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 is set as follows: the fuel flow of the precombustion stage oil way of the single general nozzle A is multiple times of the fuel flow of the precombustion stage oil way of the single enrichment nozzle B, and the fuel flow of the main fuel stage oil way of the single general nozzle A is inconsistent with the fuel flow of the main fuel stage oil way of the single enrichment nozzle B, and the fuel flow of the single general nozzle A is equal to the fuel flow of the single enrichment nozzle B.

The fuel control system determines its operating mode based on the control logic diagram shown in fig. 5.

Under normal conditions, the control loop of the fuel control system includes

steps

91, 92, 93, and 941. In this state the fuel control system is in the normal operating mode. In step 91, the sensor 6 detects the pulsating pressure in the combustion chamber 3 in real time. In step 92, the engine ecu 1 receives the detection signal output from the sensor 6. In step 93, the engine ecu 1 determines whether the pulsating pressure exceeds the limit based on the detection signal. In step 941, since the pulsating pressure is not exceeded, the fuel control system continues to remain in the normal operation mode, and the engine ecu 1 outputs a control signal to the fuel center stage control unit 2. After receiving a signal sent by the engine electronic control unit 1, the fuel center grading control unit 2 distributes fuel to four oil paths of PA, PB, MA and MB according to the input signal requirement, and enters different combustion areas of the combustion chamber 3 through the pre-combustion stage nozzle 321 and the main combustion stage nozzle 350 respectively, so as to realize the combustion chamber performance requirements of stable combustion, reduction of pollutant discharge, improvement of outlet temperature distribution and the like.

When the oscillatory combustion occurs, the control circuit of the fuel control system includes

steps

91, 92, 93, 942, and 95. In this state, the fuel control system is switched from the normal operation mode to the enrichment operation mode. In step 91, the sensor 6 detects a combustion oscillation signal due to fluctuations in the dynamic pressure inside the combustion chamber 3. In step 92, the sensor 6 transmits a detection signal to the engine ecu 1 in step 93, the engine ecu 1 determines whether the pulsating pressure exceeds the limit based on the detection signal. In step 942, due to the occurrence of the hunting combustion, the pulsation pressure exceeds the limit, the fuel control system is switched from the normal operation mode to the rich operation mode, the engine ecu 1 starts the circumferential control, and outputs a control signal. In step 95, the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 operate according to the input signal requirement, and the overall combustion heat release fluctuation characteristics of the combustion chamber 3 are changed by increasing or decreasing the pre-combustion stage fuel flow of the N general nozzles A and decreasing or increasing the main combustion stage fuel flow of the N general nozzles A, so that the flame heat release fluctuation deviates from the acoustic mode of the working environment, the coupling between the two is broken, and the effect of suppressing the combustion oscillation is achieved. Because the pre-combustion stage circumferential controller 4 and the main combustion stage circumferential controller 5 are in coordinated action, the sum of the flow values of the pre-combustion stage fuel oil and the main combustion stage fuel oil entering each fuel oil nozzle 310 is kept equal, and the outlet temperature uniformity of the combustion chamber 3 is better, so that the stable performance and the structural safety of the turbine are ensured.

In addition, the fuel control system also has a small-state working mode. In the small-state operation mode, the precombustion stage circumferential controller 4 is set to supply oil only to the precombustion stage nozzle holes 321 of the general nozzle a so as to increase the fuel flow of the precombustion stage nozzle holes 321 of the general nozzle a, thereby enhancing the stability of the flame in the area of the N general nozzles a and ensuring the flameout boundary in the small state. For example, during engine ignition, the fuel-to-air ratio of the local fuel injectors 310 increases and ignition is more likely to succeed, thereby reducing the engine ignition fuel flow; during the deceleration process of the engine, the fuel-air ratio of the local fuel nozzle 310 is increased, and the engine is not easy to flameout, so that the flameout boundary of the engine is widened.

When the fuel control system monitors a combustion oscillation signal, the fuel supply grading proportion of part of the fuel nozzles 310 is changed, the combustion heat release fluctuation state of a combustion area is changed, the overall heat release fluctuation state of the combustion chamber 3 is further changed, the coupling of the combustion chamber and the acoustic mode of a working environment is eliminated, low pollution emission is realized, combustion oscillation is inhibited, and the normal operation of the combustion chamber 3 and an engine is maintained. Because the main combustion stage circumferential controller 5, the pre-combustion stage circumferential controller 4 and the fuel oil central grading control unit 2 act in a coordinated mode, only part of the fuel oil nozzles 310 participate in enrichment combustion, the outlet temperature uniformity of the combustion chamber 3 is good, and the cooling risk is low. Under the small state, the total fuel flow entering the combustion chamber 3 is ensured to be unchanged, the pre-combustion level fuel flow of the general nozzle A is increased, the flame of the nozzle B is enriched stably, the flame is not easy to extinguish, and the flameout boundary of the engine under the small state is improved.

Although the present invention has been disclosed in terms of the preferred embodiment, it is not intended to limit the utility model, and variations and modifications may be made by one skilled in the art without departing from the spirit and scope of the utility model. Therefore, any modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope defined by the claims of the present invention, unless the technical essence of the present invention departs from the content of the present invention.

Claims

1. A fuel control system comprising:

a plurality of general nozzles, each general nozzle comprising a pre-combustion stage nozzle orifice and a main combustion stage nozzle orifice;

it is characterized by also comprising:

at least one enrichment nozzle also comprising a pre-combustion stage jet and a main combustion stage jet;

the pre-combustion stage circumferential controller is connected with the pre-combustion stage nozzles of the plurality of general nozzles through a general pre-combustion stage oil path and is also connected with the pre-combustion stage nozzles of the at least one enrichment nozzle through an enrichment pre-combustion stage oil path and is used for adjusting the fuel oil distribution proportion of the pre-combustion stage nozzles of the general nozzles and the enrichment nozzle; and

and the main combustion stage circumferential controller is connected with the main combustion stage nozzles of the plurality of general nozzles through a general main combustion stage oil way and is also respectively connected with the main combustion stage nozzles of the at least one enrichment nozzle through an enrichment main combustion stage oil way, and is used for adjusting the fuel oil distribution proportion of the main combustion stage nozzles of the general nozzles and the enrichment nozzle.

2. The fuel control system as set forth in claim 1, characterized in that it further comprises a fuel central-stage control unit, which is in oil-way connection with each of the pre-combustion stage circumferential enrichment controller and the main combustion stage circumferential enrichment controller, and is used for adjusting the fuel flow distribution ratio of the pre-combustion stage circumferential controller and the main combustion stage circumferential controller.

3. The fuel control system of claim 2, further comprising an engine electronic control unit for receiving signals and outputting control commands to the pre-combustion stage circumferential enrichment controller or/and the main combustion stage circumferential enrichment controller or/and the fuel center staging control unit.

4. The fuel control system of claim 1 having a general mode of operation in which the fuel split ratios of the pre-combustion stage circumferential controller and the main combustion stage circumferential controller are set to: the fuel flow rate of the precombustion stage of the single general nozzle is consistent with the fuel flow rate of the precombustion stage of the single enrichment nozzle, and the fuel flow rate of the main fuel stage of the single general nozzle is consistent with the fuel flow rate of the main fuel stage of the single enrichment nozzle; in the enrichment working mode, the fuel distribution proportion of the pre-combustion stage circumferential controller and the main combustion stage circumferential controller is set as follows: the fuel flow of the precombustion stage of the single general nozzle is multiple times of the fuel flow of the precombustion stage of the single enrichment nozzle, and the fuel flow of the main fuel stage of the single general nozzle is inconsistent with the fuel flow of the main fuel stage of the single enrichment nozzle, and the fuel flow of the single general nozzle is equal to the fuel flow of the single enrichment nozzle.

5. The fuel control system of claim 4, further having a low regime operating mode in which the pilot stage circumferential controller is arranged to supply fuel only to pilot stage ports of the general nozzle to increase fuel flow to the pilot stage ports of the general nozzle.

6. A fuel control system as set forth in claim 3 further comprising a sensor in signal communication with said engine electronic control unit for sensing a combustion oscillation signal.