CN108980891B

CN108980891B - Center-graded low-emission combustion chamber head with pneumatic flow guide and anti-backfire structure

Info

Publication number: CN108980891B
Application number: CN201810391862.XA
Authority: CN
Inventors: 林宇震; 宋恒; 张弛; 王建臣
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2018-04-27
Filing date: 2018-04-27
Publication date: 2020-08-21
Anticipated expiration: 2038-04-27
Also published as: CN108980891A

Abstract

The invention discloses a center-graded low-emission combustion chamber head with a pneumatic flow guide and anti-backfire structure, which adopts a pneumatic flow guide and anti-backfire design. The air flowing through the head enters the flame tube through the main combustion stage passage, the outer ring passage, the pre-combustion stage passage and the stage section passage respectively. The air flowing through the stage section passage finally enters the main combustion stage passage to force the flow field angle of the oil-gas mixture in the main combustion stage passage to be increased, so that the stage section passage structural design has the function of pneumatic flow guiding, the ignition performance is optimized, and the generation amount of pollutants is reduced. The air flowing through the outer ring channel finally enters the main combustion stage channel along the radial direction, and the tempering phenomenon is effectively prevented due to the existence of the radial speed, so that the structural design of the outer ring channel has the function of tempering prevention, and the reliability of the head structure is improved. Therefore, the structure design of the invention has the functions of pneumatic flow guiding and backfire preventing.

Description

Center-graded low-emission combustion chamber head with pneumatic flow guide and anti-backfire structure

Technical Field

The invention relates to the technical field of low-emission combustion chamber heads, in particular to a low-emission combustion chamber head with a pneumatic flow guide and anti-backfire structure.

Background

The aviation industry is known as the industry's crown, and the aircraft engine is more the "heart" of the aircraft. Aircraft engines are highly integrated products of knowledge and technology intensive, highly product and process sophisticated, and their design and manufacturing levels represent the industry level of the whole country. In the development process of civil aircraft engines, the environmental protection requirement is paid more and more attention, and then the requirement on low-emission combustion chambers is gradually increased, and the design requirement on the low-emission combustion chambers is also higher and higher.

With the international regulations concerning the control of polluting emissions, the civil aircraft engine combustion chamber emissions must meet their requirements. According to the International Civil Aviation Organization (ICAO) regulations, carbon monoxide (CO), Unburned Hydrocarbons (UHC), Smoke (Smoke), and nitrogen oxides (NOx) are the main pollutants of aviation. Among them, CO and UHC are mainly generated in a low power state in large quantities, and Smoke and NOx are mainly generated in a high power state. Therefore, the combustion zone temperature should be controlled within the window of 1700K to 1900K to reduce the generation of 4 pollutants. The key point of reducing the pollution emission is to control the temperature and the uniformity of the temperature, the key point is to improve the structure of the combustion chamber and the mode of air supply and oil supply, and the lean premixed and pre-evaporated (low-emission) combustion chamber is a common low-pollution combustion chamber, but has poor ignition performance and is easy to temper under high working conditions.

In conclusion, the invention designs the low-emission combustion chamber head with the pneumatic flow guide and anti-backfire structure, and the head has the characteristics of having the pneumatic flow guide function, optimizing the ignition performance and reducing the emission of pollutants. The second characteristic is that it has the function of anti-backfire, preventing the structural failure and damage caused by backfire.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the ignition performance of the lean premixed and pre-evaporated (low-emission) combustion chamber is optimized, and the phenomenon of backfire under high working conditions is prevented. The existing low-emission combustion chamber mainly achieves the purpose of flow guiding by changing the structure of the combustion chamber, such as designing the flanging angle of the outlet of a main combustion stage channel. However, the flow guiding effect is influenced by the working conditions, and the air flow field angle difference under different working conditions is large.

The technical scheme adopted by the invention is as follows: the invention relates to a center-graded low-emission combustion chamber head with a pneumatic flow guide and anti-backfire structure, which adopts a pneumatic flow guide and anti-backfire design. The main structure comprises a pre-burning stage oil rod, a main burning stage swirler, a main burning stage outer ring, a main burning stage oil path connecting piece, an anti-tempering ring, a stage section and a pre-burning stage swirler.

The pre-burning stage oil rod is used for supplying pre-burning stage fuel oil. The main combustion level oil path connecting piece, the main combustion level swirler, the main combustion level outer ring and the anti-tempering ring are connected in a welding mode, and a main combustion level channel and an outer ring channel are formed between the connecting structures. The outer ring channel consists of an outer ring diversion hole and an outer ring slit. The air flowing through the outer ring channel is firstly convectively cooled for the anti-backfire ring through the outer ring guide hole, and then enters the main combustion stage channel along the radial direction through the outer ring slit, so that the backfire phenomenon is effectively prevented, and the design has the anti-backfire function. Meanwhile, an internal thread is processed on the main fuel level oil passage connecting piece and can be matched with an external thread on the level section. The pre-burning stage swirler is connected with the stage section in a welding mode, and a pre-burning stage passage and a stage section passage are formed between the connecting structures. The air flowing through the passage of the stage section firstly passes through the diversion holes of the stage section to impact and cool the wall surface of the stage section and then enters the main combustion stage passage along the slit of the stage section. Because the part of air flow is large, the flow opening angle of the oil-gas mixture in the main combustion stage channel can be effectively increased, and the design has the function of pneumatic flow guiding.

The diameter of each stage section of flow guide hole is 0.4-4.0 mm, the distance from the center line to the head axis is 14.5-17.5 mm, the number of the flow guide holes distributed in the circumferential direction is 18-72, the flow guide holes distributed in the radial direction is 1-3 rows, the change range of the flow guide hole channel in the stage section along the axial direction is 2-14 mm, the cross section can be circular or rectangular, and the cross section area can be kept unchanged, gradually contracted, gradually expanded or the combination of three change shapes in the axial direction.

The diameter of the outer ring flow guide holes is 0.4-1.2 mm, the distance between the center lines of the outer ring flow guide holes and the head axis is 33.0-34.5 mm, the number of the outer ring flow guide holes is 16-96 in the circumferential direction, the outer ring flow guide holes are distributed in 1-2 rows in the radial direction, the cross section of the outer ring flow guide hole channel can be circular or rectangular, and the cross section area can be kept unchanged, gradually contracted, gradually expanded or a combination of three changes in the axial direction.

The angle of the pneumatic flow guide of the slit in the stage section can form 50-90 degrees with the axial direction, so that a better pneumatic flow guide effect is achieved; the air flow angle of the outer ring slit is 60-90 degrees with the axial direction, so that tempering is effectively prevented; the angle of the pneumatic diversion of the slit in the stage section is matched with the angle of the air flow of the slit in the outer ring, so that the pneumatic diversion and the anti-backfire effect are optimized.

The width of the slit of the stage section along the axial direction is 1.0-4.0 mm, the height of the slit along the radial direction is 4.0-10.0 mm, the shape of the cross section of the channel can be circular or polygonal, and the area of the cross section can be kept unchanged, gradually contracted, gradually expanded or the combination of the three changes along the radial direction; the width of the outer ring slit along the axial direction is 1.0-9.0 mm, the height of the outer ring slit along the radial direction is 1.0-3.5 mm, the shape of the section of the passage can be circular or polygonal, and the area of the section can be kept unchanged, gradually contracted, gradually expanded or the combination of the three changes along the radial direction; the design of the outer ring diversion hole is matched with that of the outer ring slit, and the design of the stage section diversion hole is matched with that of the stage section slit, so that the pressure drop is minimum.

The slots of the stage section and the slots of the outer ring can be distributed at the same axial position or different axial positions; the distance between the central line of the slit of the stage section and the central line of the slit of the outer ring is 0-20 mm; the ratio of the amount of air passing through the stage section slit and the outer ring slit may be 1.0 to 10.0.

Compared with the prior art, the invention has the following advantages:

(1) the ignition performance is excellent. The head adopts the structural design of pneumatic flow guiding, so that the flow field angle of the main combustion grade oil-gas mixture is increased, the ignition performance is more excellent, and the generation amount of pollutants is reduced.

(2) The head reliability is high. The head adopts an anti-backfire design, and prevents structural failure and damage caused by backfire. Can stably work under different working conditions.

(3) The structure variability is flexible. The diameters, the number and the positions of the stage section diversion holes and the outer ring diversion holes, the section shapes and the section areas of the stage section diversion hole channels and the outer ring diversion hole channels, the widths and the relative positions of the stage section slits and the outer ring slits can be adjusted and designed according to needs, and the application range is wide.

(4) The cost is low. The structural parts are produced in a machining mode, the connecting mode is threaded connection and welding, and the cost is low.

Drawings

FIG. 1 is a schematic structural view of a center staged low emission combustor head with a pneumatic deflector and anti-backfire structure according to the present invention;

FIG. 2 is an isometric view of a center staged low emission combustor head with a pneumatic deflector and anti-flashback structure of the present invention;

FIG. 3 is a schematic view of the main and pre-combustion stage air passages of the center staged low emission combustor head with pneumatic flow guide and flashback prevention structure of the present invention, wherein FIG. 3(a) is a front isometric view and FIG. 3(b) is a rear elevational view;

FIG. 4 is a schematic view of the outer ring of the main combustion stage of the center staged low emission combustor head with pneumatic flow guide and flashback prevention structure of the present invention, wherein FIG. 4(a) is a rear view and FIG. 4(b) is a cross-sectional view;

FIG. 5 is a schematic view of a stage section of a center staged low emission combustor head with a pneumatic deflector and anti-backfire configuration of the present invention, wherein FIG. 5(a) is a rear view and FIG. 5(b) is a cross-sectional view;

in the figure: the fuel oil pre-combustion device comprises a pre-combustion-stage oil rod 1, a pre-combustion-stage swirler 2, a stage section 3, a main combustion-stage oil passage connecting piece 4, a main combustion-stage swirler 5, a main combustion-stage outer ring 6 and an anti-tempering ring 7.

Detailed Description

The invention is described in detail below with reference to the following figures and embodiments:

as shown in fig. 1 and fig. 2, the head structure of the center staged low-emission combustion chamber with the pneumatic flow guiding and anti-backfire structure in the present example adopts a pneumatic flow guiding and anti-backfire design. The whole body is made of stainless steel material. Wherein, the precombustion-level oil rod is manufactured by machining, and fuel oil is provided for the precombustion level. The main combustion stage swirler 5 is connected with the main combustion stage outer ring 6 in a welding manner to form a main combustion stage air channel; the main fuel grade swirler 5 is welded with the main fuel grade oil path connecting piece 4, and a cavity formed between the two structures is a main fuel grade oil cavity. The main combustion stage outer ring 6 and the tempering-proof ring 7 are welded, and a channel formed between the two structures is an outer ring slit 8. In addition, an internal thread is processed on the main fuel stage oil passage connecting piece 4 and can be matched with an external thread on the stage section 3. The pre-combustion stage swirler 2 is connected with the stage section in a welding mode.

As shown in fig. 3, there are mainly four air passages through the head structure: a main stage channel 12, an outer ring channel 13, a pre-stage channel 14 and a stage section channel 15. A first part of air flows into the pre-combustion stage channel 14, passes through the pre-combustion stage swirler 2, is mixed with oil mist sprayed by the pre-combustion stage oil rod 1, and then flows into the flame tube to participate in combustion to form pre-combustion stage diffusion flame. The second part of air flows into the main combustion stage channel 12, flows through the main combustion stage swirler 5, is mixed with fuel oil ejected from fuel oil holes on the wall surface of the swirler to form a uniform oil-gas mixture, and flows into the flame tube to participate in combustion to form main combustion stage premixed flame. The third part of air flows into the stage section channel 15, flows through the stage section diversion holes 11 to cool the wall surface of the stage section 3, then enters the main combustion stage channel 12 through the stage section slits 10 to conduct diversion on the oil-gas mixture in the main combustion stage channel 12, so that the swirl opening angle is enlarged, the ignition performance is better, and the generation amount of pollutants is reduced. The fourth part of air flows into the outer ring channel 13, flows through the outer ring diversion holes 9, cools the anti-backfire ring, and then enters the main combustion stage channel 12 through the outer ring slit 8, and the existence of the radial speed effectively prevents the backfire phenomenon.

The diameter of each flow guide hole in each stage section is 0.4-4.0 mm, the distance between the center line and the head axis is 14.5-17.5 mm, the number of the flow guide holes in the circumferential direction is 18-72, and the flow guide holes in the radial direction are 1-3 rows. In addition, the change range of the length of the flow guide hole channel in the axial direction is 2-14 mm, the cross section can be circular or rectangular, and the cross section area can be kept unchanged, gradually contracted, gradually expanded or the combination of three change shapes in the axial direction. The air flowing through the stage section passage finally flows into the main combustion stage passage, so that the flow opening angle of the oil-gas mixture in the main combustion stage passage is increased. The design of the pneumatic flow guide structure ensures that the ignition performance of the main combustion stage is better and the generation amount of pollutants is reduced.

The diameter of the outer ring diversion holes is 0.4-1.2 mm, the distance between the center line and the head axis is 33.0-34.5 mm, the number of the outer ring diversion holes distributed in the circumferential direction is 16-96, and the outer ring diversion holes distributed in the radial direction are 1-2 rows. In addition, the cross section of the channel of the outer ring diversion hole can be circular or rectangular, and the cross section area can be kept constant, gradually contracted, gradually expanded or a combination of the three changes in the axial direction. The air flowing through the outer ring passage eventually flows into the main combustion stage passage. Because the wall surface boundary layer exists at the wall surface, the flow speed in the boundary layer is low, and the flame is easy to temper. The air flows into the main combustion stage channel along the radial direction, the development of a boundary layer is interrupted, the tempering condition is destroyed, and the tempering phenomenon is prevented.

The angle of the pneumatic flow guide of the slit in the stage section can be 50-90 degrees with the axial direction, so that a better pneumatic flow guide effect is achieved. The air flow angle of the outer ring slit is 60-90 degrees with the axial direction, and tempering is effectively prevented. The angle of the pneumatic diversion of the slit in the stage section is matched with the angle of the air flow of the slit in the outer ring, so that the pneumatic diversion and the anti-backfire effect are optimized.

The width of the slit of the stage section along the axial direction is 1.0-4.0 mm, the height of the slit along the radial direction is 4.0-10.0 mm, the shape of the section of the channel can be circular or polygonal, and the area of the section can be kept unchanged, gradually contracted, gradually expanded or the combination of the three changes along the radial direction. The width of the outer ring slit along the axial direction is 1.0-9.0 mm, the height of the outer ring slit along the radial direction is 1.0-3.5 mm, the shape of the section of the passage can be circular or polygonal, and the area of the section can be kept unchanged, gradually contracted, gradually expanded or the combination of the three changes along the radial direction. The design of the outer ring diversion hole is matched with that of the outer ring slit, and the design of the stage section diversion hole is matched with that of the stage section slit, so that the pressure drop is minimum.

As shown in FIG. 4, the main stage outer ring 6 divides the air flowing therethrough into main stage passages 12 and outer ring passages 13. Because the anti-tempering ring 7 is closely adjacent to the flame, the anti-tempering ring is radiated by the flame for a long time, and meanwhile, the anti-tempering ring 7 is thinner, has large internal temperature gradient and is easy to generate warping deformation. The air flowing through the outer ring diversion holes 9 carries out impingement cooling on the anti-backfire ring, reduces the temperature of the anti-backfire ring 7, and ensures the reliability of the head structure. The air enters the main combustion stage channel 12 through the outer ring slit 8, the development of a boundary layer is interrupted, the tempering condition is damaged, the structural failure and damage caused by tempering are prevented, and the head structure can stably work for a long time.

As shown in fig. 5, the stage section 3 divides the air flowing therethrough into an inlet pre-combustion stage passage 14 and a stage section passage 15. The stage section has a step backflow area, the flow speed in the backflow area is low, high-temperature burnt gas is mixed with unburnt gas, so that the unburnt gas is ignited, a stable ignition point of flame can be formed at the position, and the temperature is high, and large thermal stress exists at the position. The air flowing through the stage section guide hole 11 cools the wall surface of the stage section 3, reducing the wall surface temperature of the stage section 3, so that the thermal stress is reduced. The air enters the main combustion stage channel 12 through the stage section slit 10, so that the flow field angle of the oil-gas mixture in the main combustion stage channel 12 is increased, the ignition performance of the main combustion stage is better due to the pneumatic flow guide design, and the generation amount of pollutants is reduced.

The stage section slits and the outer ring slits may be distributed at the same position in the axial direction or at different positions. The distance between the central line of the slit of the stage section and the central line of the slit of the outer ring is 0-20 mm. The ratio of the amount of air passing through the stage section slit and the outer ring slit may be 1.0 to 10.0.

Claims

1. The utility model provides a hierarchical low emission combustor head in center with pneumatic water conservancy diversion and anti-backfire structure which characterized in that: the device comprises a pre-combustion-stage oil rod (1), a pre-combustion-stage swirler (2), a stage section (3), a main combustion-stage oil passage connecting piece (4), a main combustion-stage swirler (5), a main combustion-stage outer ring (6) and an anti-tempering ring (7); the pre-combustion oil rod (1) is used for supplying pre-combustion fuel oil; the main combustion stage oil path connecting piece (4), the main combustion stage swirler (5), the main combustion stage outer ring (6) and the anti-tempering ring (7) are connected in a welding manner, and a main combustion stage channel (12) and an outer ring channel (13) are formed between the connecting structures; the outer ring channel (13) consists of outer ring diversion holes (9) and outer ring slits (8), air flowing through the outer ring channel (13) firstly carries out convection cooling on the anti-backfire ring (7) through the outer ring diversion holes (9) and then enters the main combustion stage channel (12) through the outer ring slits (8) along the radial direction, the backfire phenomenon is effectively prevented, and the anti-backfire device has an anti-backfire function; meanwhile, an internal thread is processed on the main fuel level oil passage connecting piece (4) and can be matched with the external thread on the level section (3); the pre-combustion stage swirler (2) is connected with the stage section (3) in a welding mode, and a pre-combustion stage passage (14) and a stage section passage (15) are formed between the connecting structures; the air flowing through the stage section channel (15) firstly passes through the stage section diversion holes (11) to impact and cool the wall surface of the stage section (3), and then enters the main combustion stage channel (12) along the stage section slit (10), so that the flow field angle of the oil-gas mixture in the main combustion stage channel (12) can be effectively increased, and the pneumatic diversion function is realized;

the diameter of each stage section flow guide hole (11) is 0.4-4.0 mm, the distance from the center line to the head axis is 14.5-17.5 mm, the number of the flow guide holes distributed in the circumferential direction is 18-72, the flow guide holes distributed in the radial direction is 1-3 rows, the length variation range of the channel of each stage section flow guide hole (11) along the axial direction is 2-14 mm, the section shape can be circular or rectangular, and the section area can be kept constant, gradually contracted, gradually expanded or the combination of three variation shapes in the axial direction;

the diameter of the outer ring flow guide holes (9) is 0.4-1.2 mm, the distance between the center line and the head axis is 33.0-34.5 mm, the number of the outer ring flow guide holes in the circumferential direction is 16-96, the outer ring flow guide holes in the radial direction are distributed in 1-2 rows, the cross section of the channel of the outer ring flow guide holes (9) can be circular or rectangular, and the cross section area can be kept unchanged, gradually contracted, gradually expanded or the combination of three changes in the axial direction;

the angle of the pneumatic flow guide of the slit (10) in the stage section is 50-90 degrees with the axial direction, so that a better pneumatic flow guide effect is achieved; the air flow angle of the outer ring slit (8) is 60-90 degrees with the axial direction, so that tempering is effectively prevented; the angle of the pneumatic flow guide of the stage section slit (10) is matched with the airflow angle of the outer ring slit (8), so that the pneumatic flow guide and anti-backfire effects are optimized;

the width of the stage section slit (10) along the axial direction is 1.0-4.0 mm, the height along the radial direction is 4.0-10.0 mm, the shape of the section of the channel can be circular or polygonal, and the area of the section can be kept unchanged, gradually contracted or gradually expanded along the radial direction; the width of the outer ring slit (8) along the axial direction is 1.0-9.0 mm, the height along the radial direction is 1.0-3.5 mm, the shape of the cross section of the channel can be circular or polygonal, and the area of the cross section can be kept unchanged, gradually contracted and gradually expanded along the radial direction; the design of the outer ring diversion hole (9) is matched with that of the outer ring slit (8), and the design of the stage section diversion hole (11) is matched with that of the stage section slit (10), so that the pressure drop is minimum;

the stage section slits (10) and the outer ring slits (8) can be distributed at the same position or different positions in the axial direction; the distance between the central line of the stage section slit (10) and the central line of the outer ring slit (8) is 0-20 mm; the ratio of the amount of air passing through the stage section slit (10) to the amount of air passing through the outer ring slit (8) is 1.0 to 10.0.