CN109779788B - Gas-liquid coaxial shear type nozzle based on lip sawtooth design - Google Patents
Gas-liquid coaxial shear type nozzle based on lip sawtooth design Download PDFInfo
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- CN109779788B CN109779788B CN201811528464.4A CN201811528464A CN109779788B CN 109779788 B CN109779788 B CN 109779788B CN 201811528464 A CN201811528464 A CN 201811528464A CN 109779788 B CN109779788 B CN 109779788B
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- 239000007788 liquid Substances 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 12
- 239000012530 fluid Substances 0.000 claims description 3
- 238000000889 atomisation Methods 0.000 abstract description 15
- 238000002485 combustion reaction Methods 0.000 abstract description 15
- 238000002156 mixing Methods 0.000 abstract description 14
- 239000000446 fuel Substances 0.000 abstract description 11
- 238000010008 shearing Methods 0.000 abstract description 7
- 238000002679 ablation Methods 0.000 abstract description 4
- 230000006872 improvement Effects 0.000 abstract description 4
- 230000009467 reduction Effects 0.000 abstract description 2
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- 239000007789 gas Substances 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 3
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- 238000001704 evaporation Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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- 238000007373 indentation Methods 0.000 description 1
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Abstract
The invention discloses a gas-liquid coaxial shear type nozzle designed based on lip sawteeth, which comprises: an outer nozzle and an inner nozzle; wherein, the outer nozzle is sleeved on the outer surface of the inner nozzle; the outer nozzle and the inner nozzle are coaxial; the lip of the inner nozzle is positioned inside the outer nozzle; the lip of the inner nozzle is provided with a plurality of sawteeth along the circumferential direction; the inner nozzle is used for circulating liquid, and gas is circulated between the outer nozzle and the inner nozzle. The invention solves the contradiction between the improvement of fuel atomization mixing efficiency and the improvement of combustion stability of the gas/liquid coaxial shearing nozzle and the reduction of nozzle ablation risk.
Description
Technical Field
The invention belongs to the technical field of liquid rocket engine gas generators or thrust chambers, and particularly relates to a gas-liquid coaxial shear type nozzle based on a lip sawtooth design.
Background
In a liquid rocket engine, the injection and atomization process of a propellant is very critical and mainly comprises the following steps: 1) the atomization and blending process determines the combustion efficiency; 2) the injection process acoustic response is an important link for the formation and maintenance of combustion instabilities. Therefore, how to reduce the sound vibration sensitivity of the injection process and improve the combustion stability on the basis of ensuring the combustion efficiency is a very much concerned problem in the current engineering.
The coaxial shear type nozzle is widely applied to a low-temperature liquid rocket engine and is the first choice injection form of a high-performance full-flow afterburning reusable liquid oxygen/methane engine in the future. The gas/liquid coaxial shear type nozzle realizes atomization and mixing of fuel mainly through flow shear effect between gas-liquid jet flows near an outlet, and the geometrical shape of the outlet of the inner nozzle is a key influence on the process. In engineering, the momentum ratio of inner jet flow and outer jet flow is improved by adopting a mode of conical divergent inner diameter of an outlet of an inner nozzle, so that a better atomization and mixing effect is realized. However, in some cases, pure internal nozzle taper does not always achieve the desired atomization and blending effect, even because the initial fuel jet shearing process is susceptible to combustor pressure oscillations, resulting in an increased likelihood of coupled resonance between downstream combustion heat release and combustor acoustic oscillations. Thus, in practice, the inner nozzle is usually retracted inwardly from the outlet to form a retraction chamber with the outlet of the outer nozzle.
However, the above conventional approaches still have some problems, mainly including: 1) the sound vibration sensitivity in the injection process is not reduced fundamentally, and the gas-liquid fuel jet flow shearing process is still influenced by the pressure oscillation of the combustion chamber; 2) the introduction of indentation makes the combustion stability very sensitive to the length of the combustion, and the stability under variable working conditions is difficult to ensure; 3) the indented section itself is prone to form a micro-combustor, causing nozzle erosion, which seriously threatens the reliability of the entire engine.
Disclosure of Invention
The technical problem solved by the invention is as follows: the defects of the prior art are overcome, the gas-liquid coaxial shear type nozzle based on the lip sawtooth design is provided, and the contradiction between the improvement of fuel atomization mixing efficiency and the improvement of combustion stability and the reduction of nozzle ablation risk of the gas-liquid coaxial shear nozzle is solved.
The purpose of the invention is realized by the following technical scheme: a gas-liquid coaxial shear nozzle based on a lip serration design, comprising: an outer nozzle and an inner nozzle; wherein, the outer nozzle is sleeved on the outer surface of the inner nozzle; the outer nozzle and the inner nozzle are coaxial; the lip of the inner nozzle is positioned inside the outer nozzle; the lip of the inner nozzle is provided with a plurality of sawteeth along the circumferential direction; the inner nozzle is used for circulating liquid, and gas is circulated between the outer nozzle and the inner nozzle.
In the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the inner diameter of the lip of the inner nozzle is DnThe outer diameter of the lip is DwThe number of the sawteeth is N, the tooth depth of the sawteeth is H, wherein the tooth depth H, the actual jet flow speed u and the jet flow self frequency fcThe relationship between them is:
wherein f isc＝fKH×N，fKHThe natural frequency of the jet process in the original state without teeth is determined by the Strahaha number St of the jet outlet according to the engineering fluid mechanics principle
In the gas-liquid coaxial shear type nozzle designed based on the lip sawtooth, the left deflection angle of the sawtooth is α1The right deflection angle of the sawtooth is α2Difference between left and right declination angles α1-α2Not less than 10.
In the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the thickness of the inner lip of the lip is H1The thickness of the outer lip of the lip is H2The relationship between the thickness of the inner lip and the thickness of the outer lip is as follows:
in the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the inner expanding angle α of the lip is3Is 45-70 degrees.
In the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the inner expanding angle α of the lip is3Is 30-45 degrees.
In the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the outward expansion angle α of the lip4Is 45-70 degrees.
In the gas-liquid coaxial shear type nozzle based on the lip sawtooth design, the outward expansion angle α of the lip4Is 30-45 degrees.
In the gas-liquid coaxial shear type nozzle designed based on the lip sawteeth, a plurality of sawteeth are uniformly distributed along the circumferential direction of the lip.
Compared with the prior art, the invention has the following beneficial effects:
1) the circumferential saw teeth are introduced at the outlet of the inner nozzle, so that the mixing of the fuel along the circumferential direction is enhanced, the mixing distance is shortened, and the mixing efficiency is improved;
2) the invention promotes the diameter of the atomized fuel droplets to be distributed along the circumferential direction, weakens the coupling condition of the fuel atomization and evaporation process and the sound vibration of the combustion chamber, thereby improving the combustion stability of the nozzle;
3) the invention can reduce the length of the retraction section of the inner nozzle after considering the nozzle outlet sawteeth, thereby reducing the risk of ablation in the retraction section and improving the reliability of the engine.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a schematic structural diagram of a gas-liquid coaxial shear nozzle based on a lip sawtooth design according to an embodiment of the present invention;
FIG. 2(a) is a schematic diagram of the atomization effect of the gas-liquid coaxial shearing nozzle before the tooth is added according to the embodiment of the invention;
FIG. 2(b) is a schematic diagram of the atomization effect of the toothed gas-liquid coaxial shearing nozzle provided in the embodiment of the present invention;
FIG. 3(a) is a schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 3(b) is another schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 3(c) is yet another schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 3(d) is yet another schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 4(a) is a further schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 4(b) is yet another schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
FIG. 4(c) is yet another schematic view of an inner nozzle provided in accordance with an embodiment of the present invention;
fig. 4(d) is another schematic view of an inner nozzle provided in an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Fig. 1 is a schematic structural diagram of a gas-liquid coaxial shear nozzle based on a lip sawtooth design according to an embodiment of the present invention. As shown in fig. 1, the gas-liquid coaxial shear type nozzle based on the lip serration design includes: an outer nozzle 1 and an inner nozzle 2; wherein,
the outer nozzle 1 is sleeved on the outer surface of the inner nozzle 2; the outer nozzle 1 and the inner nozzle 2 are coaxial; the lip 21 of the inner nozzle 2 is located inside the outer nozzle 1; the lip 21 of the inner nozzle 2 is provided with a plurality of saw teeth 22 along the circumferential direction thereof (as shown in fig. 3(b) and 4 (b)); the inner nozzle 2 is used for the circulation of liquid and the outer nozzle 1 and the inner nozzle 2 are used for the circulation of gas.
A plurality of serrations 22 are evenly distributed along the circumferential direction of the lip 21.
According to the jet atomization principle, the flow shearing action caused by the velocity difference of the inner jet and the outer jet can cause the gas-liquid interface to be unstable, and so-called K-H waves are formed. The K-H wave determines the downstream atomization frequency and consequently the main atomization particle size distribution, and therefore the frequency f of the K-H waveKHVery critical, fKHDetermined by the strouha number St of the jet itself, which is defined as:
wherein D is the outlet diameter and u is the actual jet velocity. On the basis, the patent considers that the frequency characteristic is changed by sawtooth along the circumferential direction of the lip, as shown in fig. 4, the specific way is to machine V-shaped teeth along the circumferential direction, and the basic design parameters (taking the tooth number N ═ 10 as an example) of the V-shaped teeth include:
lip inner diameter: dn
Lip outside diameter: dw
Number of teeth: n is a radical of
Tooth depth: h
The self frequency of the jet flow after the gear is added is changed into:
fc＝fKH×N
specific examples of the parameters are shown in fig. 3(a), 3(b), 3(c), and 3(d), and differences in atomization effects of the gas-liquid coaxial shearing nozzle before and after the addition of the teeth are shown in fig. 2(a) and 2 (b).
In the actual design, the final frequency f should be setcApart from the combustion chamber characteristic frequency, and in view of the control effect, the tooth depth should be kept as far as possible in the following range, namely:
the intensified mixing of the inner and outer jets is mainly achieved by considering the circumferential interaction of the outlet flow to the vortex, as shown in fig. 4(a), 4(b), 4(c) and 4(d), and the main basic design parameters (number of teeth N ═ 10) include:
angle of left declination α1
Angle of right declination α2
Inner expanding angle α3
Outer expanding angle α4
Inner lip thickness: h1
Thickness of outer lip: h2
In actual design, in order to ensure the best blending effect, the difference α between left and right deflection angles1-α2Not less than 10, in addition, the inner and outer lip thickness should be equal, and satisfy:
the inner and outer flaring angles should take into account the compressibility of the fluid, for gas α3Or α4Should be between 30 DEG and 45 DEG, and for liquid α3Or α4Should be between 45 deg. and 70 deg..
In the embodiment, the circumferential saw teeth are introduced at the outlet of the inner nozzle, so that the mixing of the fuel along the circumferential direction is enhanced, the mixing distance is shortened, and the mixing efficiency is improved; the embodiment promotes the diameter of the atomized fuel droplets to be distributed along the circumferential direction, weakens the coupling condition of the fuel atomization and evaporation process and the sound vibration of the combustion chamber, and thus improves the combustion stability of the nozzle; the length of the retraction section of the inner nozzle can be reduced after the nozzle outlet sawteeth are considered, so that the risk of ablation in the retraction section is reduced, and the reliability of the engine is improved.
The above-described embodiments are merely preferred embodiments of the present invention, and general changes and substitutions by those skilled in the art within the technical scope of the present invention are included in the protection scope of the present invention.
Claims (7)
1. A gas-liquid coaxial shear nozzle based on lip sawtooth design is characterized by comprising: an outer nozzle (1) and an inner nozzle (2); wherein,
the outer nozzle (1) is sleeved on the outer surface of the inner nozzle (2);
the outer nozzle (1) and the inner nozzle (2) are coaxial;
the lip (21) of the inner nozzle (2) is positioned inside the outer nozzle (1);
the lip (21) of the inner nozzle (2) is provided with a plurality of sawteeth (22) along the circumferential direction;
the inner nozzle (2) is used for circulating liquid, and gas is circulated between the outer nozzle (1) and the inner nozzle (2).
2. The lip serration design based gas-liquid coaxial shear nozzle of claim 1, wherein: the inner diameter of the lip (21) of the inner nozzle (2) is DnThe outer diameter of the lip is DwThe number of the sawteeth (22) is N, the tooth depth of the sawteeth (22) is H, wherein the tooth depth H, the actual jet flow speed u and the jet flow self frequency fcThe relationship between them is:
wherein f isc＝fKH×N，fKHThe natural frequency of the jet process in the original state without teeth is determined by the Strahaha number St of the jet outlet according to the engineering fluid mechanics principle
3. The gas-liquid coaxial shear nozzle based on lip serration design as claimed in claim 1, wherein the left-hand angle of the serration (22) is α1The right deflection angle of the sawtooth (22) is α2Difference between left and right declination angles α1-α2Not less than 10.
4. The lip serration based gas-liquid coaxial shear nozzle of claim 2, wherein: the inner lip of the lip (21) has a thickness of H1The thickness of the outer lip of the lip (21) is H2The relationship between the thickness of the inner lip and the thickness of the outer lip is as follows:
5. the gas-liquid coaxial shear nozzle based on lip serration design according to claim 2, characterized in that the inner flare α of the lip (21)3Is 45-70 degrees.
6. The gas-liquid coaxial shear nozzle based on lip serration design according to claim 2, characterized by the flared angle α of the lip (21)4Is 30-45 degrees.
7. The lip serration based gas-liquid coaxial shear nozzle of claim 2, wherein: the plurality of saw teeth (22) are uniformly distributed along the circumferential direction of the lip (21).
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| CN112345257A (en) * | 2020-12-02 | 2021-02-09 | 中南大学 | Test platform for rocket engine nozzle atomization test |
| KR102480591B1 (en) * | 2021-03-30 | 2022-12-22 | 충북대학교 산학협력단 | Shear coaxial injector of rocket engine |
| CN113339159B (en) * | 2021-07-06 | 2022-08-16 | 西安航天动力研究所 | Coaxial double-centrifugal injector based on 3D printing and liquid oxygen kerosene rocket engine |
| CN114876669B (en) * | 2022-03-31 | 2024-01-02 | 中国人民解放军战略支援部队航天工程大学 | Coaxial model engine for researching tangential unstable combustion of rocket engine |
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| US6253539B1 (en) * | 1996-09-24 | 2001-07-03 | Boeing North America Inc. | Convective and turbulent shear mixing injector |
| FR2972498B1 (en) * | 2011-03-07 | 2015-12-18 | Snecma | INJECTION ELEMENT WITH TRICOAXIAL STRUCTURE FOR MIXING TWO ERGOLS |
| CN106064122B (en) * | 2015-04-24 | 2019-12-24 | 苏州中尧节能环保设备有限公司 | Sawtooth jet type evacuator |
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