CN117109029A - Blunt body flame stabilizer and aeroengine combustion assembly - Google Patents
Blunt body flame stabilizer and aeroengine combustion assembly Download PDFInfo
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- CN117109029A CN117109029A CN202311076695.7A CN202311076695A CN117109029A CN 117109029 A CN117109029 A CN 117109029A CN 202311076695 A CN202311076695 A CN 202311076695A CN 117109029 A CN117109029 A CN 117109029A
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 67
- 239000003381 stabilizer Substances 0.000 title claims abstract description 45
- 239000000446 fuel Substances 0.000 claims abstract description 24
- 230000000903 blocking effect Effects 0.000 claims description 12
- 230000007704 transition Effects 0.000 claims description 6
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 230000003116 impacting effect Effects 0.000 claims 1
- 230000001965 increasing effect Effects 0.000 abstract description 23
- 239000012530 fluid Substances 0.000 abstract description 14
- 238000002156 mixing Methods 0.000 abstract description 10
- 230000010355 oscillation Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 8
- 230000004888 barrier function Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000011105 stabilization Methods 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000000429 assembly Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
- F23R3/16—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration with devices inside the flame tube or the combustion chamber to influence the air or gas flow
- F23R3/18—Flame stabilising means, e.g. flame holders for after-burners of jet-propulsion plants
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
The application discloses a blunt flame stabilizer and an aeroengine combustion assembly, and belongs to the technical field of combustion stability control. The blunt flame stabilizer is characterized in that a stop piece is arranged in a cavity of the V-shaped blunt body, and a gap on the V-shaped blunt body is opposite to an arc-shaped groove of the stop piece, so that air flow sprayed out of the gap acts on the arc-shaped groove, and self-excited oscillation is generated by alternately flowing out of a first flow channel and a second flow channel formed between the stop piece and the V-shaped blunt body. Meanwhile, jet flows flowing out of the first flow passage and the second flow passage reach the wake flow area of the passive flame stabilizer, so that the flow characteristic of the wake flow area of the passive flame stabilizer is effectively modulated, the length of the back flow area of the passive flame stabilizer is increased, the mixing of fluid and fuel is promoted, the residence time of the fluid and the fuel in the back flow area is increased, the combustion process is controlled, and the flame combustion efficiency is improved.
Description
Technical Field
The application belongs to the technical field of combustion stability control, and particularly relates to a blunt body flame stabilizer and an aeroengine combustion assembly.
Background
For aircraft engine combustion assemblies, combustion stability is one of the basic requirements for ensuring proper operation of an aircraft engine. Only under the condition of stable flame, the fuel can be fully combusted, the combustion efficiency and performance of the engine are improved, the flight safety of the aircraft is ensured, and dangerous situations such as flame instability and the like are avoided. Because the flow field in the combustion chamber is complex and changeable, the flow speed is high, the flow field pulsation is strong, the inlet airflow speed and the fuel residence time are short, and the difficulty of flame stabilization is increased. The flame stabilizing control technology is an important means for ensuring stable combustion of the combustion assembly of the aero-engine, and the effective control technology can improve the combustion efficiency and reduce pollution emission, so that higher aviation efficiency is realized.
Common flame stabilization techniques include both pneumatic and physical stabilization techniques. The solid stabilization technology is to install solid structures such as geometric elements of a blunt body in a combustion chamber, to form partial blockage of a flow field by the blunt body, to form a low-pressure backflow area by airflow after the blunt body, to strengthen blending and change flow field distribution around flame, so as to realize efficient stable combustion. However, under the working condition close to flameout, due to the weakening of oblique pressure vortex and thermal expansion, a backflow area at the downstream of the blunt body becomes unstable, so that the flame stability boundary is narrow, the flame shape is influenced, and the problems of flame quenching, unstable combustion and the like are caused. Meanwhile, the flame stabilizer has lower combustion efficiency, uneven temperature distribution of flame sections and serious influence on the dynamic property and economy of the engine. Therefore, the blunt flame stabilizer needs to be optimized in terms of design and improvement, etc. to overcome these disadvantages, improve combustion efficiency, and ensure reliability and economy of the engine.
Disclosure of Invention
The application aims to at least solve the technical problem of lower flame combustion efficiency at present to a certain extent. To this end, the present application provides a bluff body flame holder and an aircraft engine combustion assembly.
The embodiment of the application provides a blunt flame stabilizer, which comprises: the V-shaped blunt body and the stop piece are arranged at the tail end of the V-shaped blunt body, a gap is formed at the front end of the V-shaped blunt body, and the gap is communicated with the gap; the stop piece is arranged in the cavity, and the front end of the stop piece is provided with an arc-shaped groove which is opposite to the gap; the stop piece and the V-shaped blunt body are arranged at intervals, a first flow channel and a second flow channel which are distributed on two opposite sides of the stop piece are formed between the stop piece and the V-shaped blunt body, and jet flows entering the cavity from the gap are impacted to the arc-shaped groove and alternately flow out of the first flow channel and the second flow channel to form jet flows with high-frequency self-oscillation.
Alternatively, in order to better implement the present application, the slit is disposed along and parallel to the midline of the V-shaped bluff body.
Alternatively, in order to better implement the present application, the arc-shaped groove is a minor arc groove or a semi-circular arc groove.
Alternatively, in order to better implement the present application, a circular arc transition portion is provided between the groove wall where the notch of the arc-shaped groove is located and the side wall of the stop member.
Alternatively, in order to better implement the present application, a connecting wall is disposed between the wall surface of the slit and the wall surface of the corresponding cavity, and an included angle α between the connecting wall and the wall surface of the slit is greater than 45 °.
Alternatively, in order to better implement the present application, the slits are straight slits, the connecting wall is a right angle, and the connecting wall is perpendicular to the corresponding slits.
Alternatively, in order to better implement the present application, the slit is a necking slit, the connecting wall is a straight line, and an included angle is formed between the connecting wall and a wall surface of the corresponding slit.
Optionally, in order to better implement the present application, the V-shaped blunt body includes an upper blunt body and a lower blunt body that are disposed at intervals, the gap is defined between the upper blunt body and the lower blunt body, the tail end of the upper blunt body is connected with a first baffle, the tail end of the lower blunt body is connected with a second baffle, the first baffle and the second baffle are disposed at intervals, and the tail end of the first baffle and the tail end of the second baffle gradually approach each other along the front end to the tail end of the V-shaped blunt body.
The embodiment of the application also provides an aeroengine combustion assembly, which comprises: the combustor comprises a combustion chamber, a diffusion section arranged at the upstream of the combustion chamber, a fuel nozzle arranged at the tail end of the diffusion section and a spray pipe arranged at the downstream of the combustion chamber, wherein the blunt body flame stabilizer is arranged between the fuel nozzle and the combustion chamber.
Alternatively, in order to better realize the application, the windward blocking area of the V-shaped blunt body/the cross section area of the combustion chamber is the overall blocking ratio, and the overall blocking ratio is 14-20%.
Compared with the prior art, the application has the following beneficial effects:
according to the blunt body flame stabilizer provided by the application, the stop piece is arranged in the cavity of the V-shaped blunt body, and the gap on the V-shaped blunt body is opposite to the arc-shaped groove of the stop piece, so that the air flow sprayed out of the gap acts on the arc-shaped groove, and flows out of the first flow passage and the second flow passage formed between the stop piece and the V-shaped blunt body alternately to generate self-oscillation. Meanwhile, jet flows flowing out of the first flow passage and the second flow passage reach the wake flow area of the passive flame stabilizer, so that the flow characteristic of the wake flow area of the passive flame stabilizer is effectively modulated, the length of the back flow area of the passive flame stabilizer is increased, the mixing of fluid and fuel is promoted, the residence time of the fluid and the fuel in the back flow area is increased, the combustion process is controlled, and the flame combustion efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a schematic structural diagram of an engine combustion chamber;
FIG. 2 shows a schematic diagram of a blunt flame stabilizer;
FIG. 3 illustrates a flow diagram of the gas flow within the bluff body flame holder of FIG. 2;
FIG. 4 shows a schematic structural view of a stopper;
FIG. 5 shows another schematic structural view of the stopper;
FIG. 6 shows a schematic view of a construction of the slit;
FIG. 7 shows another schematic view of the slit;
FIG. 8 shows a flow diagram of a closed V-shaped bluff body;
FIG. 9 shows a flow diagram of an open V-shaped bluff body;
FIG. 10 illustrates a flow diagram of the bluff body flame holder of FIG. 2;
FIG. 11 shows another schematic structural view of a bluff body flame holder;
FIG. 12 shows a schematic airflow diagram of the bluff body flame holder of FIG. 11.
Reference numerals:
100. a bluff body flame holder; 200. a diffuser section; 300. a fuel nozzle; 400. a combustion chamber; 500. a spray pipe;
110. v-shaped blunt body; 111. an upper blunt body; 112. a lower blunt body; 113. a slit; 113a, a first slit wall; 113b, a second slit wall; 114. a connecting wall; 116. a first baffle; 117. a second baffle;
120. a cavity; 121. a first flow passage; 122. a second flow passage; 120a, a first cavity wall; 120b, a second cavity wall;
130. a stopper; 131. an arc-shaped groove; 132. a transition section; 133. a tip portion;
141. a first vortex; 142. and a second vortex.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that all the directional indicators in the embodiments of the present application are only used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture, and if the specific posture is changed, the directional indicators are correspondingly changed.
In the present application, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present application.
The application is described below with reference to specific embodiments in conjunction with the accompanying drawings:
the present embodiment provides a bluff body flame holder 100 that enables more efficient combustion and stability of fuel after installation in the combustion chamber 400 of an aircraft engine.
Specifically, the blunt flame stabilizer 100 is constructed as shown in fig. 2, including a V-shaped blunt body 110 and a stopper 130.
The V-shaped blunt body 110 has a V-shaped structure, wherein the thickness of the V-shaped blunt body 110 gradually increases from the front end of the V-shaped blunt body 110 to the rear end of the V-shaped blunt body 110, the front end of the V-shaped blunt body 110 is a tip 133 of the V-shaped structure, the rear end of the V-shaped blunt body 110 has a cavity 120 formed of the V-shaped structure, and the cavity 120 has an isosceles triangle shape. A slit 113 is formed at the front end of the V-shaped blunt body 110, and the slit 113 communicates with the cavity 120 such that an air flow can enter the cavity 120 from the slit 113. The slit 113 divides the V-shaped blunt body 110 into an upper blunt body 111 and a lower blunt body 112, the upper blunt body 111 and the lower blunt body 112 being positioned at both sides of the slit 113 of the V-shaped blunt body 110, respectively, and the cavity 120 being positioned between the upper blunt body 111 and the lower blunt body 112.
The stopper 130 is disposed in the cavity 120, a gap is formed between the stopper 130 and the V-shaped blunt body 110, and a first flow channel 121 and a second flow channel 122 are formed between the stopper 130 and the V-shaped blunt body 110, the first flow channel 121 and the second flow channel 122 are disposed on opposite sides of the stopper 130, and an air flow entering through the gap 113 at the front end of the V-shaped blunt body 110 is split by the stopper 130, so that the air flow flows out of the tail region of the V-shaped blunt body 110 from the first flow channel 121 and/or the second flow channel 122.
Specifically, a first slit wall 113a is provided on the upper blunt body 111, and a second slit wall 113b is provided on the lower blunt body 112, and the slit 113 is defined by the first slit wall 113a and the second slit wall 113b spaced apart from each other. The upper blunt body 111 is provided with a first cavity wall 120a, the lower blunt body 112 is provided with a second cavity wall 120b, and the cavity 120 is defined between the first cavity wall 120a and the second cavity wall 120 b. The first flow path 121 is formed by the first cavity wall 120a of the upper blunt body 111 and one side wall of the stopper 130, and the second flow path 122 is formed by the second cavity wall 120b of the lower blunt body 112 and the other side wall of the stopper 130.
The front end of the stop member 130 is provided with an arc-shaped groove 131, the arc-shaped groove 131 is recessed from the front end of the stop member 130 to the rear end of the stop member 130, and the arc-shaped surface of the arc-shaped groove 131 is opposite to the gap 113. The air flow ejected from the slit 113 of the V-shaped blunt body 110 forms a jet flow, the jet flow diverges after impinging on the arc-shaped groove 131 of the stopper 130, a part of the jet flow can flow along the arc-shaped groove 131 in a deflection way, and in the process, part of the jet flow drives part of air in the arc-shaped groove 131 to rotate to form a first vortex 141, and the other part of the jet flow can flow along the arc-shaped groove 131 in a deflection way, and in the process, drives the other part of air in the arc-shaped groove 131 to rotate to form a second vortex 142, and the spiral directions of the first vortex 141 and the second vortex 142 are opposite. At the same time, the jet accumulated in the arc-shaped groove 131 may flow out of the first flow channel 121 and/or the second flow channel 122 to form a jet, and the jet may reach the wake area of the blunt body.
In addition, since the fluid has instability in the flowing process, the jet formed by the fluid ejected from the slit 113 also has instability, and the proportion of the upward deflection or the downward deflection of the jet is continuously changed, the volume and the density of the formed first vortex 141 and the volume and the density of the formed second vortex 142 are correspondingly changed, so that the first vortex 141 and the second vortex 142 also have instability.
The flow change of the jet will be described in detail with reference to fig. 3.
As shown at a in fig. 3, the jet stream from the slit 113 forms a first vortex 141 and a second vortex 142 in opposite directions within the arcuate recess 131.
As shown at b in fig. 3, the size of the first and second vortices 141 and 142 formed varies due to instability of the jet, and a large amount of jet is deflected upward when the second vortex 142 occupies a larger volume in the cavity of the arc-shaped groove 131 than the first vortex 141 occupies in the cavity of the arc-shaped groove 131.
As shown in fig. 3 c, after the jet deflects upward, the space under the jet is further increased, so that the volume and intensity of the second vortex 142 are continuously increased, and the space occupied by the second vortex 142 is gradually moved to a position close to the center, during which the angle of upward deflection of the jet is continuously increased, the size of the cavity of the arc-shaped groove 131 occupied by the first vortex 141 is further compressed, the cavity area of the arc-shaped groove 131 occupied by the first vortex 141 is continuously reduced, and the first vortex 141 is further pushed to gradually move toward the inlet of the first flow channel 121. When the first vortex 141 moves to the inlet of the first flow channel 121, the first vortex 141 will block the first flow channel 121, so that only a small part of the jet can flow out of the first flow channel 121, but a large part of the jet cannot flow out of the first flow channel 121, so that the jet flow is accumulated near the inlet of the first flow channel 121, the air pressure of the upper half part of the arc-shaped groove 131 is increased, the jet flow newly ejected from the gap 113 is induced to deflect downwards, the space above the jet flow is increased, the first vortex 141 extruded to the inlet of the first flow channel 121 is released, the volume and the intensity of the first vortex 141 are gradually increased, the jet flow is pushed to the central position, the jet flow is gradually deflected to the central position, and the jet flow returns to the middle position as shown at d in fig. 3.
As shown at e in fig. 3, as the first vortex 141 continues to increase, the jet will be pushed downward, deflecting the jet downward.
As shown at f in fig. 3, after the jet deflects downward, the space above the jet is further increased, so that the volume and intensity of the first vortex 141 are continuously increased, the space occupied by the first vortex 141 is gradually moved to a position close to the center, during this process, the downward deflection angle of the jet is continuously increased, the size of the cavity of the arc-shaped groove 131 occupied by the second vortex 142 is further compressed, the cavity area of the arc-shaped groove 131 occupied by the second vortex 142 is continuously reduced, and the second vortex 142 is further pushed to gradually move toward the inlet of the second flow passage 122. When the second vortex 142 moves to the inlet of the second flow channel 122, the second vortex 142 seals the second flow channel 122, so that only a small part of the jet can flow out of the second flow channel 122, but most of the jet cannot flow out of the second flow channel 122, so that the jet is accumulated near the inlet of the second flow channel 122, the air pressure of the lower half part of the arc-shaped groove 131 is increased, the jet newly sprayed out of the gap 113 is induced to deflect upwards, the space below the jet is increased, the second vortex 142 extruded to the inlet of the second flow channel 122 is released, the volume and the intensity of the second vortex 142 are gradually increased, the jet is pushed to the central position, the jet is gradually deflected to the central position until the volume occupied by the second vortex 142 in the cavity of the arc-shaped groove 131 is larger than the volume occupied by the first vortex 141 in the cavity of the arc-shaped groove 131, and the jet is deflected upwards.
After the jet deflects upward, the jet repeatedly undergoes the flow changes a-f in fig. 3, so that the first vortex 141 and the second vortex 142 are continuously changed, and the jet generates high-frequency self-oscillation through the cooperation of the V-shaped blunt body 110 and the stopper 130. The jet from the slit 113 is alternately deflected upward and downward, so that the jet is switched between flowing out of the first flow channel 121 and flowing out of the second flow channel 122, and the jet flowing out of the first flow channel 121 and the second flow channel 122 forms a jet with high-frequency self-oscillation, so that the jet reaching the wake area behind the blunt body forms periodic self-oscillation. The flow characteristic of the blunt body wake zone can be effectively modulated due to the injection wake zone of the self-oscillation high-frequency jet flow, so that the length of the back flow zone of the blunt body flame stabilizer 100 is increased, the mixing of fluid and fuel is promoted, the residence time of the fluid and fuel in the back flow zone is increased, the control of the combustion process is realized, the more efficient combustion effect and stability are realized, and the engine has better economy and reliability.
Preferably, the width dimension d of the slit 113 is 3mm, and when the width is smaller than this dimension, the fluid is not likely to enter the slit 113 to form a jet, and when the width of the slit 113 is larger than this dimension, the self-oscillation phenomenon is not likely to be formed or the generated oscillation is not likely to be sustained.
Further, the slit 113 is disposed along a center line of the V-shaped blunt body 110 such that the upper blunt body 111 and the lower blunt body 112 are symmetrically disposed. And the slit 113 is a straight slit 113 to reduce resistance to the air flow into the slit 113 so that the jet ejected from the slit 113 has a higher velocity.
Preferably, the stop 130 is also disposed along the center line of the V-shaped blunt body 110, so that the arc-shaped grooves 131 on the stop 130 are symmetrically disposed along the center line of the V-shaped blunt body 110, and thus self-oscillation can be generated more stably after the jet enters the arc-shaped grooves 131.
Further, the arc groove 131 is a minor arc groove or a semi-circular arc groove, so that the limit of the two sides of the arc groove 131 to the first vortex 141 and the second vortex 142 is reduced, when the second vortex 142 extrudes the first vortex 141, the first vortex 141 can stably move to the first flow channel 121, and similarly, when the first vortex 141 extrudes the second vortex 142, the second vortex 142 can stably move to the first flow channel 121, and then high-frequency self-oscillation jet flow is stably generated.
Further, as shown in fig. 4, a circular arc transition portion 132 is disposed at the connection between the arc-shaped groove 131 and the side wall of the stop member 130. To reduce flow losses during the flow of the jet from the circular arc groove into the first flow passage 121 and/or to reduce flow losses during the flow of the jet from the circular arc groove into the second flow passage 122.
Preferably, the radius R of the arc transition portion 132 can be adjusted according to the radius R of the arc groove 131, and in this embodiment, the ratio of R/R is 5% -12%. When the ratio is greater than this range, the end formed between the arc-shaped groove 131 and the side wall of the stopper 130 is too sharp, which may cause an obstruction to the flow bypass of the jet. When the ratio is smaller than this range, the end formed between the arc-shaped groove 131 and the side wall of the stopper 130 is too gentle to form self-oscillation.
Of course, in some alternative embodiments, the transition portion 132 may not be provided, so that the two ends of the arc-shaped groove 131 form the tip portion 133 as shown in fig. 5, so that, although self-oscillation can be generated, the tip portion 133 can generate a certain resistance to the jet flow, and the fluidity of the jet flow is affected, so that the generated self-oscillation may be unstable.
If the wall surface of the slit 113 is directly connected to the wall surface of the cavity 120, that is, the first slit wall 113a is directly connected to the first cavity wall 120a, and the second slit wall 113b is directly connected to the second cavity wall 120 b. When the air flow is ejected from the slit 113, the air flow flows along the wall surface of the cavity 120 due to the coanda effect, so that the first vortex 141 and the second vortex 142 cannot be generated, and the jet cannot generate self-oscillation in the arc-shaped groove 131. Therefore, in this embodiment, the connection wall 114 is disposed between the wall surface of the slit 113 and the wall surface of the corresponding cavity 120, and the included angle between the connection wall 114 and the wall surface of the corresponding slit 113 is greater than 45 °, so that a sufficiently large inclination angle is formed between the connection wall 114 and the wall surface of the slit 113, thereby avoiding the attachment of the air flow flowing through the slit 113 to the connection wall 114, and enabling the jet to be injected into the arc-shaped groove 131.
Fig. 6 shows a schematic view of a structure of the slit 113 and the connecting wall 114, in which the slit 113 is a straight slit 113, and the first slit wall 113a and the second slit wall 113b forming the slit 113 are parallel, on the basis of which the connecting wall 114 is rectangular. The right-angle side of the connection wall 114 provided between the first slit wall 113a and the first cavity wall 120a is perpendicular to the corresponding first slit wall 113a, and the right-angle side of the connection wall 114 provided between the second slit wall 113b and the second cavity wall 120b is perpendicular to the corresponding second slit wall 113 b. The right angle connecting wall 114 is provided with a right angle groove, and the right angle groove can effectively avoid the wall attachment phenomenon.
Of course, in some alternative embodiments, the slit 113 may be a non-straight slit 113, that is, the first slit wall 113a and the second slit wall 113b forming the first slit 113 are not parallel, as shown in fig. 7, the slit 113 has a reduced structure, and the distance between the first slit wall 113a and the second slit wall 113b is gradually reduced from the front end to the rear end of the V-shaped blunt body 110, so that the fluid flowing through the slit 113 can be accelerated. Meanwhile, the connecting wall 114 is in a straight line, the deflection angle α between the connecting wall 114 disposed between the first slit wall 113a and the first cavity wall 120a and the corresponding first slit wall 113a is greater than 45 °, and the deflection angle α between the connecting wall 114 disposed between the second slit wall 113b and the second cavity wall 120b and the corresponding second slit wall 113b is also α, which is greater than 45 ° and can avoid the coanda effect to some extent.
Further, the tail end of the stop member 130 in the embodiment is a plane, and the tail end of the stop member 130 is perpendicular to the center line of the V-shaped blunt body 110, so as to avoid interference of the tail end of the stop member 130 to the radiation.
Preferably, the rear end of the upper blunt body 111, the rear end of the lower blunt body 112, and the rear end of the stopper 130 are located on the same plane.
Fig. 8 to 10 show time-averaged velocity flow diagrams of the blunt flame stabilizer 100 of different structures. The structure of the blunt flame stabilizer 100 shown in fig. 8 includes only the V-shaped blunt body 110, and the V-shaped blunt body 110 is a closed structure, and no slit 113 is provided. The structure of the blunt body flame stabilizer 100 shown in fig. 9 includes only the V-shaped blunt body 110, and the V-shaped blunt body 110 has an open structure provided with a slit 113. Fig. 10 illustrates the bluff body flame holder 100 provided in the above embodiment, and the structure of the bluff body flame holder 100 includes a V-shaped bluff body 110 and a stopper 130.
As can be seen by comparing fig. 8, 9 and 10, the bluff body flame holder 100 of the present embodiment of fig. 9 is optimally designed, in which the momentum and mass mixing effect of the wake zone is enhanced due to the injection of the self-oscillating high-frequency jet in the wake zone, and the length of the wake zone average velocity streamline is elongated in the axial direction, as compared with the closed bluff body flame holder 100 of fig. 8 and the V-shaped bluff body flame holder 100 of fig. 9 with the front end open. Compared to the closed blunt flame stabilizer 100 of FIG. 8, the length of the recirculation zone was increased by 0.5X/W and the length of the recirculation bubble was increased by 0.25X/W. Compared to the open-front blunt flame holder 100 of fig. 9, the return bubbles of the return zone are symmetrical about the central axis, increasing the lateral maximum width by 0.2Y/W. With respect to the blunt flame stabilizer 100 of fig. 9, which is open at the front end, the jet stream deflected upward by the fluid passing through the slit is not symmetrical to the central axis.
Compared with the conventional blunt flame control technology, the blunt flame stabilizer 100 with the stop piece 130 provided in this embodiment can increase the length of the wake zone of the V-shaped blunt body 110, increase the residence time of high-temperature fuel gas and fuel in the back flow zone, increase the residence time of main flow and fuel in the back flow zone, and improve the fuel blending and combustion efficiency.
Based on the blunt flame stabilizer 100 described above, another blunt flame stabilizer 100 is also provided in the embodiments of the present application. The structure of the bluff body flame holder 100, as shown in fig. 11, includes a V-shaped bluff body 110 and a stopper 130, and is different from the bluff body flame holder 100 described above in that a first baffle 116 is provided at the rear end of an upper bluff body 111 constituting the V-shaped bluff body 110, a second baffle 117 is provided at the rear end of a lower bluff body 112 constituting the V-shaped bluff body 110, and the entire stopper 130 is disposed in a cavity defined by the upper bluff body 111, the first baffle 116, the second baffle 117, and the lower bluff body 112 in common. The first barrier 116 and the second barrier 117 are spaced apart from each other along the front end to the rear end of the V-shaped blunt body 110, and the rear end of the first barrier 116 and the rear end of the second barrier 117 are gradually close to each other so that a necking structure is formed between the first barrier 116 and the second barrier 117. The jet from the first flow channel 121 is guided and collected by the first baffle 116, and the jet from the second flow channel 122 is guided and collected by the second baffle 117, so that the two jet streams are more fully mixed in the tail region of the blunt body, and the mixture formed after fully mixing is ejected from the gap between the first baffle 116 and the second baffle 117.
It should be noted that by adjusting the dimensions and deflection angles of the blunt body first baffle 116 and the second baffle 117, the lateral and longitudinal swirling motion can be changed, thereby promoting the diffusion and convection of fluids, increasing the contact area between fluids, and enhancing the effective mixing of different fluids. The dimensions of the first baffle 116 herein refer to the length L and thickness D of the first baffle 116 and the dimensions of the second baffle 117 refer to the length and thickness of the second baffle 117. The deflection angle of the first baffle 116 refers to the angle θ between the first baffle 116 and the flow direction of the main flow, and the deflection angle of the second baffle 117 refers to the angle γ between the second baffle 117 and the plane in which the trailing end of the blunt body is located.
Further, in the present embodiment, in the case where the upper blunt body 111 and the lower blunt body 112 are symmetrical, the first baffle 116 and the second baffle 117 are also symmetrically disposed to achieve a better mixing effect. At this time, the angle θ is equal to the angle γ.
Based on the blunt flame stabilizer 100, the present application further provides an aeroengine combustion assembly, which has a structure as shown in fig. 1, and comprises a diffuser section 200 disposed upstream of a combustion chamber 400, a fuel nozzle 300 and a nozzle 500 disposed downstream of the combustion chamber 400, wherein the fuel nozzle 300 is disposed at the tail end of the diffuser section 200, and the blunt flame stabilizer 100 is disposed between the fuel nozzle 300 and the combustion chamber 400. The high pressure gas is diffused by the diffuser section 200 and mixed with the fuel sprayed from the fuel nozzle 300 to form a mixture, the mixture is fully doped and mixed after passing through the blunt flame stabilizer 100, and then the mixture enters the combustion chamber 400 to be combusted, and flame generated by combustion is sprayed from the spray pipe 500. The blunt flame stabilizer 100 can make the mixture produce self-oscillation so as to improve the mixing of air flow and fuel, thus the combustion of the aeroengine combustion assembly is more sufficient, more efficient combustion effect and stability are realized, and the engine has better economy and reliability.
Further, in the above-described combustion assembly, the diffuser 200, the fuel nozzle 300, the bluff body combustion stabilizer, the combustion chamber 400, and the nozzle 500 are all located in the main flow path of the engine. Also, the number of blunt body combustion stabilizers may be one or more. When the number of the bluff body combustion stabilizers is plural, the plural bluff body combustion stabilizers are arranged at intervals in the radial direction of the main flow passage.
The windward blocking area of the V-shaped blunt body 110/the sectional area of the combustion chamber 400 is an overall blocking ratio of 14% to 20%. In the overall blocking ratio in this range, it is possible to ensure that the cavity 120 of the V-shaped blunt body 110 can accommodate the stopper 130, and at the same time, it is also possible to avoid flow loss and flow field instability caused by an excessively large blocking ratio.
It should be noted that the windward blocking area of the V-shaped blunt body 110 refers to the projected area of the V-shaped blunt body 110 in the radial direction of the combustion chamber 400 in the main flow passage. When the number of the blunt body combustion stabilizers is one, the windward blocking area of the V-shaped blunt body 110 is the projected area of the V-shaped blunt body 110 in the radial direction of the combustion chamber 400 in the main flow channel; when the number of the bluff body combustion stabilizers is plural, the windward blocking area of the V-shaped bluff body 110 is the sum of the projected areas of the V-shaped bluff body 110 in the radial direction of the combustion chamber 400 in the main flow passage. The cross-sectional area of the combustion chamber 400 refers to the area of the combustion chamber 400 in the radial direction of the corresponding position of the main flow path.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Further, one skilled in the art can engage and combine the different embodiments or examples described in this specification.
Claims (10)
1. A blunt flame stabilizer comprising:
the V-shaped blunt body (110), wherein a cavity (120) is formed at the tail end of the V-shaped blunt body (110), a gap (113) is formed at the front end of the V-shaped blunt body (110), and the gap (113) is communicated with the cavity (120);
the stop piece (130), the stop piece (130) is arranged in the cavity (120), the front end of the stop piece (130) is provided with an arc-shaped groove (131), the arc-shaped groove (131) is opposite to the gap (113),
the stop piece (130) and the V-shaped blunt body (110) are arranged at intervals, a first flow channel (121) and a second flow channel (122) which are distributed on two opposite sides of the stop piece (130) are formed between the stop piece (130) and the V-shaped blunt body (110), and jet flows entering the cavity (120) from the gap (113) are impacted to form jet flows alternately from the first flow channel (121) and the second flow channel (122) after impacting the arc-shaped groove (131) so as to form high-frequency self-oscillation jet flows.
2. A bluff body flame holder according to claim 1, wherein the slit (113) is arranged along the centre line of the V-shaped bluff body (110) and parallel to the centre line of the V-shaped bluff body (110).
3. A blunt flame stabilizer as claimed in claim 1, wherein the arc-shaped groove (131) is a minor arc groove or a semicircular arc groove.
4. A blunt flame stabilizer as claimed in claim 1, characterized in that a transition (132) of circular arc is provided between the groove wall of the groove opening of the arc-shaped groove (131) and the side wall of the stop (130).
5. A blunt flame stabilizer according to claim 1, characterized in that a connecting wall (114) is arranged between the wall of the slit (113) and the wall of the corresponding cavity (120), the angle α between the connecting wall (114) and the wall of the slit (113) being larger than 45 °.
6. A blunt flame stabilizer as claimed in claim 5, wherein the slit (113) is a straight slit (113), the connecting wall (114) is at right angles, and the connecting wall (114) is perpendicular to the corresponding slit (113).
7. A blunt flame stabilizer according to claim 5, wherein the slit (113) is a pinch slit (113), the connecting wall (114) is a straight line, and an angle between the connecting wall (114) and a wall surface of the slit (113) is formed.
8. A blunt body flame stabilizer according to claim 1, wherein the V-shaped blunt body (110) comprises an upper blunt body (111) and a lower blunt body (112) which are arranged at intervals, the gap (113) is defined between the upper blunt body (111) and the lower blunt body (112), a first baffle (116) is connected to the tail end of the upper blunt body (111), a second baffle (117) is connected to the tail end of the lower blunt body (112), the first baffle (116) and the second baffle (117) are arranged at intervals along the front end to the tail end of the V-shaped blunt body (110), and the tail end of the first baffle (116) and the tail end of the second baffle (117) are gradually close.
9. An aircraft engine combustion assembly comprising: a combustion chamber (400) and a diffuser (200) placed upstream of the combustion chamber (400), a fuel nozzle (300) placed at the tail end of the diffuser (200) and a nozzle (500) placed downstream of the combustion chamber (400), wherein the blunt body flame stabilizer (100) according to any of claims 1-8 is placed between the fuel nozzle (300) and the combustion chamber (400).
10. An aircraft engine combustion assembly according to claim 9, characterized in that the V-shaped bluff body (110) has a total blocking ratio of the windward blocking area/the cross-sectional area of the combustion chamber (400) of 14-20%.
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| CN202311076695.7A CN117109029B (en) | 2023-08-25 | 2023-08-25 | Blunt body flame stabilizer and aeroengine combustion assembly |
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| CN202311076695.7A CN117109029B (en) | 2023-08-25 | 2023-08-25 | Blunt body flame stabilizer and aeroengine combustion assembly |
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| CN117109029B (en) | 2024-02-02 |
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