CN114811652A

CN114811652A - Aero-engine combustion chamber adopting MILD combustion

Info

Publication number: CN114811652A
Application number: CN202210100877.2A
Authority: CN
Inventors: 金武; 汤潮伟; 李建中; 翟维阔; 姚倩
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2022-01-27
Filing date: 2022-01-27
Publication date: 2022-07-29
Anticipated expiration: 2042-01-27
Also published as: CN114811652B

Abstract

The invention discloses an aero-engine combustion chamber adopting MILD combustion, and relates to the field of aero-engine combustion chamber structures. Through the mode that sets up guide plate and fuel and spout backward, make the combustion chamber carry out the MILD burning, and then combustion temperature distributes evenly, improves combustion efficiency, reduces pollutant discharge. The aeroengine combustion chamber comprises a diffuser, a flame tube and a combustion chamber casing; the aircraft engine combustion chamber also comprises a nozzle and a flow distribution plate, the nozzle is connected with fuel, the nozzle extends into the flame tube, and the nozzle faces the swirler; the splitter plate is fixedly connected between the flame tube and the combustion chamber casing, and the front part of the splitter plate extends into the diffuser; and spaces are reserved between the splitter plate and the flame tube and between the splitter plate and the combustion chamber casing. The MILD is applied to the combustion chamber of the aero-engine on the whole, MILD combustion is carried out in the combustion chamber, the combustion temperature distribution is uniform, the combustion efficiency is improved, and pollutant emission is reduced.

Description

Aero-engine combustion chamber adopting MILD combustion

Technical Field

The invention relates to the field of aero-engine combustion chamber structures, in particular to an aero-engine model combustion chamber adopting MILD combustion.

Background

The development direction of military engines is to pursue higher thrust-weight ratio under the condition of meeting the reliability requirement, and civil engines pay more attention to low pollution, low oil consumption and high safety. Therefore, the combustion chamber is required to develop towards the direction of high temperature rise and high heat capacity, the requirement on the combustion chamber is still continuously improved, the temperature rise level of the combustion chamber of the aero-engine with high thrust-weight ratio in the future can reach or even exceed 1400K, and the combustion organization mode of the swirler main combustion hole of the conventional combustion chamber is difficult to meet the requirement of the combustion performance of the high-temperature combustion chamber with the head air inflow exceeding 60 percent of the total air inflow of the combustion chamber.

In the exploration process for solving the problems, various advanced combustion organization modes are proposed at home and abroad. The MILD (flame-free combustion) combustion is considered as a combustion organization mode with great potential, the MILD is also called as flameless combustion and is carried out under the conditions of high temperature and low oxygen, and the volume fraction of oxygen in a reaction zone is less than 15 percent and is in a distributed reaction, so that the limit waste heat recovery can be realized. Under the condition, the method has the advantages of low peak combustion temperature, small NOx emission, uniform distribution of temperature field and radiant heat flux, and has the characteristics of good combustion stability, strong fuel adaptability and low combustion noise. Given the numerous advantages of MILDs, researchers have taken this organization of combustion into a variety of situations. For example, in patent "a total oxygen pulverized coal combustion method and a device used by the method", patent No. CN104864392A, the purpose of energy saving, resource saving, carbon reduction and emission reduction can be realized by forming MILD combustion in a boiler furnace through large velocity difference jet flow of oxygen and pulverized coal. Patent No. CN113566198A, changes the cross section area of the outlet of the secondary air pipeline by moving the front and back positions of the speed regulating block, and has the advantages of strong load adaptability, simple structure and the like. Patent No. CN112013543B, it can ensure to establish stable flameless combustion in the furnace, and realize high-efficient recovery of heat while realizing low NOx emission. The patent "a can realize the radiant tube of flameless burning", patent No. CN213810620U, can realize not needing to select specific radiant tube combustor, can entrainment flue gas in order to dilute fuel and combustion air, accomplish the flameless burning in the radiant tube.

At present, MILD combustion is mainly used in the fields of industrial kilns such as heating furnaces, tunnel kilns, sleeve kilns and the like, and meanwhile, a great deal of research work is focused on the combustion aspect of gas fuel MILD to obtain a lot of important conclusions. The research on the combustion of the solid fuel MILD mainly aims at the aspects of pulverized coal boilers and the like, and achieves certain results. Liquid fuels, due to their complexity, have started their MILD combustion research late. The main combustion chamber is mainly liquid fuel, and the development of the combustion chamber faces many challenges, so how to apply the MILD combustion to the main combustion chamber becomes a technical problem to be solved by those skilled in the art.

Disclosure of Invention

Aiming at the problems, the invention provides the combustion chamber of the aircraft engine adopting MILD combustion, and the MILD combustion is carried out in the combustion chamber by arranging a guide plate and a fuel reverse injection mode, so that the combustion temperature is uniformly distributed, the combustion efficiency is improved, and the pollutant emission is reduced.

The technical scheme of the invention is as follows: the combustion chamber of the aircraft engine comprises a diffuser 1, a flame tube 6 and a combustion chamber casing 8, wherein the flame tube 6 is arranged in the combustion chamber casing 8, the rear parts of the flame tube and the combustion chamber casing are fixedly connected, the front part of the flame tube 6 is fixedly provided with a swirler 2 through a fixing plate 3, and the diffuser 1 is fixedly arranged at the front part of the combustion chamber casing 8, so that an air inlet channel is formed between the diffuser 1 and the swirler 2;

the aircraft engine combustion chamber further comprises a nozzle 7 and a flow distribution plate 4, wherein the nozzle 7 is connected with fuel, the nozzle 7 extends into the flame tube 6, and the nozzle 7 is arranged towards the swirler 2;

the flow distribution plate 4 is fixedly connected between the flame tube 6 and the combustion chamber casing 8, and the front part of the flow distribution plate 4 extends into the diffuser 1; and a space is reserved between the splitter plate 4 and the flame tube 6 and between the splitter plate 4 and the combustion chamber casing 8. Like this, the front portion of guide plate 4 is located between diffuser 1 and the flame tube 6, the air inlet that will get into diffuser 1 divides into two air currents, the mainstream passes the anterior region that directly gets into the swirler place of flow distribution plate, the secondary flow gets into between flow distribution plate 4 and the combustion chamber machine casket 8 earlier, backward get into between flow distribution plate 4 and the flame tube 6 again, thereby carry out the heat transfer of forcing through rib post 5 at this in-process, mix with the mainstream at last, the inlet air temperature is improved, simultaneously, nozzle 7 forms the relative flow with the incoming flow, and then produce the high-speed jet flow, the entrainment high temperature gas, reduce oxygen concentration, form the MILD burning.

Further, the splitter plate 4 is fixedly connected with the flame tube 6 through a plurality of rib columns 5.

The plurality of rib columns 5 are uniformly distributed on the outer wall of the flame tube 6 in an array. The rib columns 5 between the guide plate 4 and the flame tube 6 can perform forced heat exchange with secondary flow to improve the temperature of the secondary flow, and meanwhile, the rib columns can replace cooling holes in the flame tube of a conventional combustion chamber, reduce the wall temperature of the flame tube, play a role in cooling, and greatly relieve the contradiction of large air consumption and short air consumption of the combustion chamber of the aero-engine. On the other hand, the rib columns 5 can play a role of fixing and supporting, and connect and fix the guide plate 4 and the flame tube 6.

The rear part of the flame tube 6 is fixedly connected with the rear part of the combustor casing 8, and the rear parts of the flame tube and the combustor casing are kept sealed. To ensure that the secondary flow enters between the splitter plate 4 and the combustor casing 8, and then must reversely enter between the splitter plate 4 and the flame tube 6 to perform forced heat exchange with the rib post 5.

The invention has the beneficial effects that: the utility model provides a, the guide plate is admitted air with the combustion chamber and is divided into two strands of air intakes, and the secondary flow forces the heat transfer in the duct, further strengthens the heat transfer through the rib post between guide plate and the flame tube, and then improves the temperature of secondary flow, joins with the mainstream afterwards, under the condition of not adding other heat sources, utilizes the waste heat for the import temperature rises, and combustion strength increases, and combustion efficiency improves greatly. And secondly, reverse spraying is performed by a nozzle, the nozzle of the conventional combustion chamber and the main stream are mainly sprayed in the same direction, in order to be beneficial to MILD, high-speed spraying is performed by the reverse spraying mode of the nozzle and the main stream, high-temperature fuel gas in the flame tube is sucked, and oxygen in the combustion chamber is reduced.

The invention realizes the purpose of applying MILD to the combustion chamber of the aeroengine on the whole, and MILD combustion is carried out in the combustion chamber, so that the combustion temperature is uniformly distributed, the combustion efficiency is improved, and the pollutant emission is reduced.

Drawings

FIG. 1 is a schematic structural diagram of the present application,

figure 2 is a perspective view of figure 1,

figure 3 is a schematic view of the structure of a baffle,

figure 4 is a schematic view of the structure of the flame tube,

FIG. 5 is a profile view of the present case;

in the figure, 1 is a diffuser, 2 is a swirler, 3 is a fixed plate, 4 is a guide plate, 5 is a rib column, 6 is a flame tube, 7 is a nozzle, and 8 is a combustor casing.

Detailed Description

In order to clearly explain the technical features of the present patent, the following detailed description of the present patent is provided in conjunction with the accompanying drawings.

The invention is shown in figures 1-5, comprising a diffuser 1, a combustion chamber casing 8, a flame tube 6, a swirler 2, a guide plate 4, a rib column 5 and a nozzle 7;

the guide plate 4 is located between the diffuser 1 and the flame tube 6, and can divide the inlet air into two air flows, and the secondary flow carries out the forced heat transfer through the rib post 5, mixes with the mainstream, improves the inlet air temperature, and nozzle 7 forms the relative flow with the incoming flow simultaneously, and then produces high-speed jet flow, and the entrainment high temperature gas reduces oxygen concentration, forms the MILD burning.

The rib column between the guide plate 4 and the flame tube 6 can perform forced heat exchange with secondary flow, so that the temperature of the secondary flow is increased, meanwhile, cooling holes in the flame tube of a conventional combustion chamber can be replaced, the wall surface temperature of the flame tube is reduced, the cooling effect is achieved, and the contradiction of large air consumption and short air consumption of the combustion chamber of the aero-engine is greatly relieved. On the other hand, the rib columns 5 can play a role of fixing and supporting, and connect and fix the guide plate 4 and the flame tube 6.

The fuel nozzle 7 in the scheme is in a reverse spraying mode and moves relative to incoming flow to form high-temperature jet flow, so that fuel gas is sucked in an entrainment mode, and the oxygen concentration is reduced. Finally, the air inlet temperature is increased through the guide plate and the fuel nozzle adopts a reverse spraying mode to form MILD combustion.

Regarding the working principle of the invention:

the principle of the MILD is to achieve flameless combustion of gaseous fuels by preheating high temperature air and injecting fuel at high velocity, a major test phenomenon of flameless combustion being the absence of a significant flame front within the combustion chamber. And no ultrahigh temperature area exists in the combustion chamber, and the temperature distribution is more uniform. Accordingly, the formation of thermal type NO is suppressed, and the effect of low-emission combustion can be achieved.

To create MILD combustion, i.e., by preheating air and high-speed fuel injection: the air flow from the compressor enters the diffuser, then the air flow can be mainly divided into two parts, one part of the air flow enters the guide plate and the duct of the combustion chamber casing, the other part of the air flow enters the guide plate and is called as a main flow, so that the main flow rotates into the flame tube under the action of the swirler, a backflow area is formed in the flame tube, a stable combustion and reliable ignition favorable environment is created, a nozzle of a conventional combustion chamber is often arranged in the swirler, so that oil-gas mixing is facilitated, in the case, in order to achieve MILD combustion, the nozzle adopts a reverse injection mode, the nozzle is arranged on the flame tube and flows relative to the incoming flow, so that high-speed jet flow is formed, high-temperature fuel gas in the flame tube is sucked, and a low-oxygen environment is created. The effect of guide plate is in order to realize preheating the air, the secondary flow flows at inside and outside duct, and in the runner of guide plate and flame tube casing, the annular rib post has evenly been arranged for preheating the secondary flow, the burning is mainly gone on in the flame tube, the heat that produces through the burning carries out the heat transfer to the flame tube, and the rib post of installation has further strengthened heat transfer, so the secondary flow is at the in-process that flows, and the temperature rises gradually, and then mixes at the head with the mainstream, the inlet air temperature increases, realizes the MILD burning.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. The combustion chamber of the aero-engine adopting MILD combustion is characterized by comprising a diffuser (1), a flame tube (6) and a combustion chamber casing (8), wherein the flame tube (6) is arranged in the combustion chamber casing (8), the rear parts of the flame tube and the combustion chamber casing are fixedly connected, the front part of the flame tube (6) is fixedly provided with a swirler (2) through a fixing plate (3), the diffuser (1) is fixedly arranged at the front part of the combustion chamber casing (8), and therefore an air inlet channel is formed between the diffuser (1) and the swirler (2);

the aircraft engine combustion chamber further comprises a nozzle (7) and a flow distribution plate (4), the nozzle (7) is connected with fuel, the nozzle (7) extends into the flame tube (6), and the nozzle (7) faces the swirler (2);

the flow distribution plate (4) is fixedly connected between the flame tube (6) and the combustion chamber casing (8), and the front part of the flow distribution plate (4) extends into the diffuser (1); and spaces are reserved between the splitter plate (4) and the flame tube (6) and between the splitter plate (4) and the combustion chamber casing (8).

2. An aircraft engine combustion chamber using MILD combustion as claimed in claim 1, characterized in that the splitter plate (4) is fixedly connected to the liner (6) by means of a plurality of rib posts (5).

3. An aircraft engine combustion chamber using MILD combustion according to claim 1, characterized in that a plurality of rib columns (5) are uniformly distributed in an array on the outer wall of the flame tube (6).

4. An aircraft engine combustor using MILD combustion as claimed in claim 1, characterized in that the rear part of the liner (6) is fixedly connected to the rear part of the combustor casing (8) and the rear parts of both are kept sealed.