Application of Enthalpy Deficit Flamelet Model in Spray Combustion Simulation
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摘要: 基于OpenFOAM的求解器，使用大涡模拟结合纯气相火焰面生成流形方法进行了喷雾燃烧模拟，并采用简单的扣焓处理来考虑蒸发热损失.该求解器首先借助悉尼乙醇喷雾火焰标模EtF7进行了验证.预测的气相平均温度和液滴统计数据与实验数据吻合良好，精度与喷雾火焰面模型接近.湍流-化学反应相互作用建模处理可能对模拟精度有更大影响.然后，对一个真实的航空发动机折流燃烧室进行了两组工况的数值模拟.仿真结果合理展现了两种工况下喷雾火焰燃烧的不同特征，并且预测的总压损失值接近于测量值.
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关键词:
- 喷雾燃烧 /
- 大涡模拟 /
- 火焰面生成流形 /
- 航空发动机折流燃烧室
Abstract: An OpenFOAM-based solver for spray combustion simulation with the large eddy simulation (LES) and the flamelet generated manifold (FGM) method, was developed. A simple reduction of the temperature was employed to account for the evaporative heat loss. The solver was firstly validated against the Sydney piloted ethanol spray flame benchmark EtF7. The predicted mean gas temperature and droplet statistics correspond well with the experimental data and have similar accuracy to the spray flamelet model. The turbulence-chemistry interaction modeling may have a larger influence on the simulation accuracy. Then a realistic gas turbine slinger combustor was simulated with 2 sets of operating conditions. The simulation results reveal different flame characteristics of the 2 working conditions. The predicted total pressure losses are close to the measured values.-
Key words:
- spray combustion /
- large eddy simulation /
- flamelet generated manifold /
- gas turbine slinger combustor
1) (我刊编委王利坡来稿) -
图 2 悉尼喷雾燃烧室计算域及网格
Figure 2. The computation domain and mesh of the Sydney spray combustor
图 4 不同网格预测得到在轴向位置x/D=30处的气相平均温度T、液滴Sauter平均直径Smd和液滴轴向平均速度Ux的径向分布
Figure 4. Predicted radial profiles of mean gas temperature T, Sauter mean droplet diameter Smd and axial mean droplet velocity Ux at x/D=30 with different meshes
图 5 y=0截面的瞬时和平均速度场、温度场、混合分数场
注 为了解释图中的颜色，读者可以参考本文的电子网页版本，后同.
Figure 5. Instantaneous and mean velocity magnitude, temperature and mixture fraction distributions at section y=0
图 6 预测气相平均温度与实验值在不同轴向位置的径向分布
Figure 6. Predicted radial profiles of the mean gas temperature with the experimental data in 3 different axial positions
图 7 预测液滴Smd与实验值在不同轴向位置的径向分布
Figure 7. Predicted radial profiles of spray droplets Smd with the experimental data in 6 different axial positions
图 8 预测液滴轴向平均速度与实验值在不同轴向位置的径向分布
Figure 8. Predicted radial profiles of the axial mean droplet velocity with the experimental data in 6 different axial positions
图 11 y=0截面的预测瞬时速度分布和流线图
Figure 11. Predicted velocity distributions and streamlines at section y=0
图 12 y=0截面的预测瞬时和平均总温分布
Figure 12. Predicted instantaneous and mean total temperature distributions at section y=0
图 13 温度测量截面的预测瞬时和平均总温分布
Figure 13. Predicted instantaneous and mean total temperature distribution at temperature measurement section
表 1 液相引起的源项表达式
Table 1. Expressions of liquid source terms
source term expression Sρ $ -\frac{1}{V_c} \sum\limits_p \dot{m}_p N_p$ Su, i $ \frac{1}{V_c} \sum_p m_p N_p\left[\left(U_{p, i}^{t_n+\Delta t}-U_{p, i}^{t_n}\right) / \Delta t-g_i\right]-\frac{1}{V_c} \sum\limits_p \dot{m}_p N_p U_{p, i}^{t_n}$ 
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表 2 两组不同工况的测量数据
Table 2. Measured data in 2 working conditions
index working condition 1 working condition 2 air inlet mass flow rate ṁair/(kg·s-1) 2.313 2.707 fuel inlet mass flow rate ṁfuel/(g·s-1) 13.8 31.7 fuel air mass ratio (F/A)/% 0.596 6 1.171 7 air inlet temperature Tair/K 300 300 fuel inlet temperature Tfuel/K 300 300 air inlet total pressure Pt, air/kPa 305.103 408.172 total pressure loss ΔPt/kPa 50.912 74.861
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表 3 进程变量源项在不同燃烧区域的条件均值
Table 3. Conditional means of progress variable source terms in different combustion zones
working condition ωY/(kg·m-3·s-1) ξ=-1 ξ=+1 working condition 1 5.03 4.44 working condition 2 13.82 7.03
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