天然气/空气三维火焰传播特性与胞状不稳定性数值模拟

王麒骄; 郑玮琳; 王娇; 曾文

doi:10.13224/j.cnki.jasp.20230670

天然气/空气三维火焰传播特性与胞状不稳定性数值模拟

doi: 10.13224/j.cnki.jasp.20230670

沈阳航空航天大学航空发动机学院，沈阳 110136

基金项目: 辽宁省教育厅项目面上项目（LJKMZ20220537）

详细信息

作者简介:
王麒骄（1999-），女，硕士生，主要从事碳氢燃料基础燃烧特性研究

通讯作者:
郑玮琳（1989-），女，副教授，博士，主要从事燃烧室流动与反应动力学研究。E-mail：wlzheng@sau.edu.cn

中图分类号: V231.2；TK401
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出版历程
- 收稿日期: 2023-10-21
- 网络出版日期: 2025-07-13

Numerical simulation of three-dimensional flame propagation characteristics and cellular instability of natural gas/air

School of Aero-engine，Shenyang Aerospace University，Shenyang 110136，China

摘要

摘要:
为系统研究天然气/空气层流预混火焰传播特性与不稳定性，采用自适应网格细化的三维瞬态大涡模拟方法，对不同初温、初压和当量比下的天然气/空气球形火焰开展了高精度数值模拟。首先，验证了常温常压下的仿真数据，火焰发展形态与实验相比较为吻合，临界火焰半径与理论预测趋势相同；其次，分析不同初始工况下天然气/空气火焰的关键参数，揭示了初始条件对火焰固有不稳定性的主导机理；最后，基于旋转切面的快速傅里叶变换开展了火焰结构的扰动分析，揭示了扰动与拉伸速率的复杂相互作用。结果表明：改变初温对火焰形态影响甚微；而升高初压会加剧火焰锋面的裂纹分裂、增加细胞数量，使火焰厚度减薄更显著，对火焰稳定性的影响更为突出。此外，还会增强波数介于 4～15 范围内的短波扰动能量，促使不稳定波长向短波方向拓展；而初温和当量比对扰动波数范围的影响较小。
- 天然气 /
- 大涡模拟 /
- 火焰传播 /
- 不稳定性 /
- 扰动分析
Abstract:
To systematically study the flame propagation characteristics and flame instability of natural gas/air premixed flames at different initial temperatures, initial pressures, and equivalence ratios, high-precision numerical simulations were carried out by using a 3D, transient large eddy simulation method with adaptive mesh refinement modeling. Firstly, simulation results at atmospheric temperature and pressure were validated. The simulated flame morphology was in good agreement with experimental data, and the simulated critical flame radius was also in good agreement with that obtained by theoretical prediction. Secondly, key parameters of natural gas/air flames under different initial conditions were analyzed, revealing the dominant mechanism by which initial conditions influenced the inherent instability of flames. Finally, perturbation analysis of the flame structure was conducted based on the Fast Fourier Transform of cross-sections, revealing the complex interaction between perturbations and stretch rates. The results indicated that different initial temperatures had little effect on the flame morphology, but as the initial pressure increased, the crack splitting on the flame front gradually intensified, and the number of cells on the flame surface increased. Increasing the initial pressure had a greater effect on the reduction of flame thickness, while the density ratios were not sensitive to changes of initial pressure. Therefore, the initial pressure had a more significant effect on the flame stability. The disturbance energy of the wave numbers ranging from 4 to 15 increased significantly with initial pressure, and the disturbances with smaller wavelengths developed consequently. By contrast, the initial temperature and equivalence ratio had little effect on the wave number range of disturbances.
- nature gas /
- large eddy simulation /
- flame propagation /
- instability /
- perturbation analysis

HTML

图 1 球体计算域与初始网格划分

Figure 1. Spherical computing domain and initial meshing

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图 2 自适应网格动态加密示意图

Figure 2. Schematic diagram of dynamic adaptive mesh refinement

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图 3 不同时间步长下球形火焰半径与火焰传播速度的变化规律

Figure 3. Variation of flame radius and flame propagation speed under different time steps

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图 4 天然气/空气球形火焰传播过程仿真图与实验纹影图对比

Figure 4. Comparison between simulated contour image and the experimental schlieren image of natural gas/air spherical flame propagation

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图 5 火焰半径与火焰传播速度模拟结果与实验结果对比（T=300 K，p=0.1 MPa，ϕ=1.0）

Figure 5. Comparison of flame radius and flame propagation speed of simulated and experimental results （T=300 K，p=0.1 MPa，ϕ=1.0）

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图 6 不同初始条件下天然气/空气球形火焰的火焰形态

Figure 6. Flame morphology of natural gas/air spherical flame under various initial conditions

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图 7 初始条件对天然气/空气混合气体火焰传播的影响

Figure 7. Effect of initial conditions on flame propagation of natural gas/air mixtures

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图 8 不同初始条件下天然气/空气混合气体的半岛结构曲线

Figure 8. Peninsula structure of natural gas/air mixtures under various initial conditions

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图 9 不同条件下天然气/空气混合气体的密度比变化

Figure 9. Calculated density ratio (σ) of natural gas/air mixtures under various initial conditions

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图 10 不同初始条件下天然气/空气混合气体的临界火焰半径

Figure 10. Comparison of critical flame radius of calculated and simulated value of natural gas/air mixtures under various initial conditions

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图 11 不同条件下天然气/空气混合气体的火焰面厚度变化

Figure 11. Variation in flame thickness of natural gas/air mixtures under various initial conditions

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图 12 火焰锋面胞状结构与局部流线分布（T=300 K，p=0.5 MPa，ϕ=0.8）

Figure 12. Cellular structure of flame front and local streamline distribution （T=300 K，p=0.5 MPa，ϕ=0.8）

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图 13 天然气/空气预混火焰锋面扰动的演变特性（ϕ=1.0）

Figure 13. Evolution of disturbances of natural gas/air premixed flame （ϕ=1.0）

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图 14 不同条件下的天然气/空气预混火焰拉伸的演变

Figure 14. Flame stretch of natural gas/air premixed flame under various initial conditions

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表 1 计算工况设置

Table 1. Computational case setup

工况	初始条件
工况	温度T/K	压力p/MPa	当量比$ \phi $
A1	300	0.5	0.8
A2	300	0.5	1.0
A3	300	0.5	1.2
B1	300	1.0	0.8
B2	300	1.0	1.0
B3	300	1.0	1.2
C1	350	0.5	0.8
C2	350	0.5	1.0
C3	350	0.5	1.2
D1	350	1.0	0.8
D2	350	1.0	1.0
D3	350	1.0	1.2
E1	400	0.5	0.8
E2	400	0.5	1.0
E3	400	0.5	1.2
F1	400	1.0	0.8
F2	400	1.0	1.0
F3	400	1.0	1.2

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