CN112879949B - Backflow cover for air inlet hole in wall surface of combustion chamber of micro turbojet engine - Google Patents
Backflow cover for air inlet hole in wall surface of combustion chamber of micro turbojet engine Download PDFInfo
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- CN112879949B CN112879949B CN202110067267.2A CN202110067267A CN112879949B CN 112879949 B CN112879949 B CN 112879949B CN 202110067267 A CN202110067267 A CN 202110067267A CN 112879949 B CN112879949 B CN 112879949B
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 110
- 239000002737 fuel gas Substances 0.000 claims description 6
- 230000001502 supplementing effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
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Classifications
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- 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
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- Engineering & Computer Science (AREA)
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- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a backflow cover for a wall surface air inlet of a combustion chamber of a micro turbojet engine, which comprises a first backflow cover arranged on a cold side wall surface of an outer ring of the combustion chamber and a second backflow cover arranged on a hot side wall surface of the outer ring of the combustion chamber; the first backflow cover wraps the front half part of the main combustion hole along the incoming flow direction, and the second backflow cover wraps the rear half part of the main combustion hole along the incoming flow direction; when the airflow reaches the wall surface of the combustion chamber, the airflow climbs along the first backflow cover at a fixed angle and enters the main combustion hole, and part of the airflow flows along the second backflow cover in the direction opposite to the direction forming a certain angle with the incoming flow to form a backflow area. The invention can form a part of backflow zone near the main combustion zone for supplementing combustion, thereby greatly improving the problems of short combustion residence time and insufficient combustion caused by small overall size of the combustion chamber of the micro turbojet engine; meanwhile, the uniformity of combustion in the combustion chamber is improved, the overall combustion efficiency is improved, and the more excellent overall performance of the micro turbojet engine is obtained.
Description
Technical Field
The invention belongs to the field of combustion of a micro turbojet engine, and particularly relates to a backflow cover for an air inlet hole in the wall surface of a combustion chamber of the micro turbojet engine.
Background
The miniature turbojet engine has the advantages of small volume, small mass, large thrust-weight ratio and the like, and is widely applied to military and civil fields. For the aviation field, the unmanned aerial vehicle of small-size intelligent development plays more and more important effect in aspects such as national security, real-time reconnaissance, long-range survey, calamity prevention, and miniature turbojet engine is also paid more and more attention as its power source. In addition, the micro engine can also be used as a power source of missiles, target planes and the like and an auxiliary power device of a large airplane, and has a very wide application market in the field of aviation. Meanwhile, the micro turbojet engine has the characteristics of relatively simple structure, short research and development period and low cost, and also contains core technologies of various aspects of the gas turbine, so that the micro turbojet engine can be used as a verification platform of various new concepts and technologies, can quickly accumulate research and development experiences, synchronously applies the related technologies to medium and large engines or transplants the related technologies into a ground gas turbine, and is used in the fields of distributed energy systems, military vehicle auxiliary power and the like. The overall performance of the engine is limited by the performance of the single component, wherein the combustion chamber is the most important high-temperature component, and the working condition is also extremely poor. Under the action of high-temperature and high-pressure combustion flame, the combustion chamber is subjected to high-intensity thermal load and thermal shock load, and is accompanied with a certain degree of mechanical vibration load. Meanwhile, the overall size of the micro turbojet engine is small, and the size of the combustion chamber is correspondingly reduced, so that the problems of insufficient combustion residence time, insufficient combustion sufficiency and the like in the combustion chamber are often caused. Therefore, in order to improve the combustion efficiency of the combustion chamber and prolong the service life of the combustion chamber, and further improve the overall performance of the micro turbojet engine, it is necessary to reasonably optimize the problems of insufficient combustion of the combustion chamber and the like.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a backflow cover for an air inlet on the wall surface of a combustion chamber of a micro turbojet engine, which can effectively improve the overall combustion efficiency and the combustion uniformity of the combustion chamber by forming partial backflow near a main combustion area of the combustion chamber for afterburning, thereby improving the performance of the overall turbojet engine.
The technical scheme is as follows: the invention comprises a first reflow cover arranged on the cold side wall surface of the outer ring of the combustion chamber and a second reflow cover arranged on the hot side wall surface of the outer ring of the combustion chamber; the first backflow cover wraps the front half part of the main combustion hole along the incoming flow direction, and the second backflow cover wraps the rear half part of the main combustion hole along the incoming flow direction; when the airflow reaches the wall surface of the combustion chamber, the airflow climbs along the first backflow cover at a fixed angle and enters the main combustion hole, and part of the airflow flows along the second backflow cover in the direction opposite to the direction forming a certain angle with the incoming flow to form a backflow area.
The first backflow cover and the second backflow cover are spherical backflow covers, backflow afterburning is formed, and meanwhile, aerodynamic loss is greatly reduced due to the spherical radian surfaces.
Spherical included angle theta of first backflow cover1The range of the secondary combustion hole is 30-60 degrees, the diameter of the spherical surface is the same as the aperture of the main combustion hole, and the secondary combustion effect is optimal in the range.
Spherical included angle theta of the second backflow hood2The range of the secondary combustion hole is 30-60 degrees, the diameter of the spherical surface is the same as the aperture of the main combustion hole, and the secondary combustion effect is optimal in the range.
The spherical center of the first backflow cover coincides with the circle center of the upper surface of the main combustion hole, the spherical center of the second backflow cover coincides with the circle center of the lower surface of the main combustion hole, and the circle centers of the upper surface and the lower surface of the main combustion hole are located on the same central axis.
The rotation central axis of the first return flow cover is vertical to the air flowing direction, and the extending direction of the spherical surface of the first return flow cover is the same as the air flowing direction.
The rotation central axis of the second backflow cover is perpendicular to the flowing direction of the high-temperature fuel gas, and the extending direction of the spherical surface of the second backflow cover is opposite to the flowing direction of the high-temperature fuel gas.
Has the advantages that: compared with the prior art, the invention has the beneficial effects that: (1) partial backflow can be formed near the main combustion area of the combustion chamber for afterburning, so that the overall combustion efficiency and the combustion uniformity of the combustion chamber are effectively improved; (2) the backflow cover adopts a spherical surface shape, so that backflow afterburning can be formed, the aerodynamic loss is greatly reduced due to the spherical radian surface, and the overall total pressure loss of the combustion chamber is not greatly influenced; (3) the spherical diameter with the same aperture as the main combustion hole is adopted, the size of the backflow cover is reduced while the main combustion hole is wrapped to the maximum extent, and the influence of overlarge size on the main combustion structure is avoided.
Drawings
FIG. 1 is a block diagram of a micro turbojet engine combustion chamber with the present invention in use;
FIG. 2 is a schematic cross-sectional view taken along A-A of FIG. 1;
FIG. 3 is an enlarged view of a portion of FIG. 2;
FIG. 4 is an annotated cross-sectional view of the present invention;
FIG. 5 is a vector diagram of the central section of an original model without the reflow mask of the present invention;
FIG. 6 is a central cross-sectional vector diagram of the model with the reflow mask of the present invention disposed;
FIG. 7 is an air intake flow diagram of the main burner holes of the original model without the return flow cover of the present invention;
FIG. 8 is a schematic view of the inlet flow of the primary burner ports in the model after placement of the reflow housing of the present invention;
FIG. 9 is a front-rear comparison diagram of various main evaluation parameters of a combustion chamber after the backflow hood is arranged.
Detailed Description
The invention is described in further detail below with reference to specific embodiments and the attached drawings.
As shown in FIG. 1, the backflow hood of the invention is arranged around the second row of main combustion holes for the air inlet hole on the combustion chamber wall surface of the micro turbojet engine, and the backflow hood comprises a first backflow hood arranged on the cold side wall surface of the combustion chamber outer ring and a second backflow hood arranged on the hot side wall surface of the combustion chamber outer ring. The first backflow cover wraps the front half part of the main combustion hole in the incoming flow direction, and the second backflow cover wraps the rear half part of the main combustion hole in the incoming flow direction.
As shown in fig. 2 and 3, the first reflow hood and the second reflow hood are spherical reflow hoods. In this embodiment, the rotation central axis of the first reflow cover is perpendicular to the air flowing direction, and the extending direction of the spherical surface of the first reflow cover is the same as the air flowing direction. The rotation central axis of the second backflow cover is vertical to the flowing direction of the high-temperature fuel gas, and the extending direction of the spherical surface of the second backflow cover is opposite to the flowing direction of the high-temperature fuel gas. When the airflow reaches the wall surface of the combustion chamber, the airflow firstly climbs a certain angle along the first backflow cover, and after entering the main combustion hole, part of the airflow flows along the second backflow cover in the direction opposite to the direction forming a certain angle with the incoming flow direction to form a backflow area. Meanwhile, the spherical center of the first backflow cover coincides with the circle center of the upper surface of the main combustion hole, the spherical center of the second backflow cover coincides with the circle center of the lower surface of the main combustion hole, and the circle centers of the upper surface and the lower surface of the main combustion hole are located on the same central axis.
As shown in FIG. 4, the spherical angle θ of the first reflow mask1The range of the spherical surface is 30-60 degrees, the diameter of the spherical surface is the same as the aperture of the main burning hole, and the general diameter D is 2-5 mm. Spherical included angle theta of second backflow hood2The range of the spherical surface is 30-60 degrees, the diameter of the spherical surface is the same as the aperture of the main burning hole, and the general diameter D is 2-5 mm. First and second reflow hoods having a spherical angle theta1And theta2The consistency is not necessarily kept, and the adjustment can be specifically carried out according to different working conditions. Through simulation verification, the spherical angle theta1And theta2The design is between 30 and 60 degrees, the effect of generating partial backflow zone for afterburning is best, the backflow zone generated by an excessively small spherical angle is not obvious, and an excessively large spherical angle can cause certain influence on a main combustion structure.
As shown in the figures 5 and 6, the comparison shows that a certain backflow area can be generated in the areas before and after the air intake of the second row of main combustion holes by adopting the spherical backflow cover around the outer ring main combustion holes of the combustion chamber of the micro turbojet engine, so that the combustion residence time is increased, the combustion sufficiency is improved, and the overall combustion efficiency of the combustion chamber is further improved.
As shown in fig. 7 and fig. 8, it is obvious from comparison that the intake air in the original model enters the main combustion zone for mixing combustion and then flows towards the downstream outlet, after the spherical backflow cover model is arranged, the intake air reversely enters the main combustion zone at a certain angle for mixing combustion, and a backflow zone appears in a local area, and the streamline of the whole backflow zone gradually flows towards the downstream outlet in a spiral shape, so that the combustion residence time is greatly increased, and the mixing combustion in the main combustion zone is further enhanced.
As shown in fig. 9, after the spherical backflow hood is arranged, the overall combustion efficiency of the combustion chamber is obviously improved from 95.2% of the original model to about 97%. The overall total pressure loss of the combustion chamber is basically unchanged, but an excessive spherical angle may have a certain influence on the total pressure loss. Compared with the original model, the OTDF of the combustion chamber outlet is slightly reduced from 0.42 of the original model to 0.37, which shows that the backflow zone generated by the spherical backflow cover model improves the temperature distribution of the downstream outlet to a certain extent due to further improving the combustion sufficiency. The overall performance of the micro turbojet engine is enhanced.
Claims (7)
1. The utility model provides a backward flow cover that is used for miniature turbojet engine combustion chamber wall inlet port which characterized in that: the first backflow hood is arranged on the cold side wall surface of the outer ring of the combustion chamber, and the second backflow hood is arranged on the hot side wall surface of the outer ring of the combustion chamber; the first backflow cover wraps the front half part of the main combustion hole along the incoming flow direction, and the second backflow cover wraps the rear half part of the main combustion hole along the incoming flow direction; when the airflow reaches the wall surface of the combustion chamber, the airflow climbs along the first backflow cover at a fixed angle and enters the main combustion hole, and part of the airflow flows along the second backflow cover in the direction opposite to the direction forming a certain angle with the incoming flow to form a backflow area.
2. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 1, wherein: the first backflow cover and the second backflow cover are spherical backflow covers.
3. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 2, wherein: spherical included angle theta of first backflow cover1The range of the spherical surface is 30-60 degrees, and the diameter of the spherical surface is the same as the aperture of the main burning hole.
4. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 2, wherein: spherical included angle theta of the second backflow hood2The range of the spherical surface is 30-60 degrees, and the diameter of the spherical surface is the same as the aperture of the main burning hole.
5. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 2, wherein: the spherical center of the first backflow cover coincides with the circle center of the upper surface of the main combustion hole, the spherical center of the second backflow cover coincides with the circle center of the lower surface of the main combustion hole, and the circle centers of the upper surface and the lower surface of the main combustion hole are located on the same central axis.
6. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 2, wherein: the rotation central axis of the first return flow cover is vertical to the air flowing direction, and the extending direction of the spherical surface of the first return flow cover is the same as the air flowing direction.
7. The reverse flow cover for an intake port in a combustion chamber wall surface of a micro turbojet engine as claimed in claim 2, wherein: the rotation central axis of the second backflow cover is perpendicular to the flowing direction of the high-temperature fuel gas, and the extending direction of the spherical surface of the second backflow cover is opposite to the flowing direction of the high-temperature fuel gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110067267.2A CN112879949B (en) | 2021-01-19 | 2021-01-19 | Backflow cover for air inlet hole in wall surface of combustion chamber of micro turbojet engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110067267.2A CN112879949B (en) | 2021-01-19 | 2021-01-19 | Backflow cover for air inlet hole in wall surface of combustion chamber of micro turbojet engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112879949A CN112879949A (en) | 2021-06-01 |
| CN112879949B true CN112879949B (en) | 2022-04-05 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202110067267.2A Active CN112879949B (en) | 2021-01-19 | 2021-01-19 | Backflow cover for air inlet hole in wall surface of combustion chamber of micro turbojet engine |
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Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2929689B1 (en) * | 2008-04-03 | 2013-04-12 | Snecma Propulsion Solide | GAS TURBINE COMBUSTION CHAMBER WITH SECTORIZED INTERNAL AND EXTERNAL WALLS |
| US9982890B2 (en) * | 2013-11-20 | 2018-05-29 | Pratt & Whitney Canada Corp. | Combustor dome heat shield |
| CN104676650B (en) * | 2015-01-30 | 2017-01-11 | 北京航空航天大学 | Reverse flow combustor allowing wider range of stable running |
| CN108561896B (en) * | 2018-03-15 | 2020-04-10 | 西北工业大学 | Take doublestage guide vane's miniature engine flame tube |
| CN108758690B (en) * | 2018-05-31 | 2020-08-21 | 广州珠江天然气发电有限公司 | Combustion chamber for a gas turbine |
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