Numerical simulation of gasoline-air thermal ignition induced by continuous hot wall
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摘要: 为了对油气在持续热壁下热着火发生过程进行数值模拟,耦合化学动力学模型、流体动力学模型及辐射传热模型,建立了油气热着火的统一模型。基于实验工况,模拟了受限空间中油气在持续热壁条件下热着火发生过程,并分析了温度、压力流场的演变特征,以及不同位置处温度、压力、层流速度、湍流速度和组分质量分数的变化曲线。通过模拟,发现油气热着火过程存在3个阶段,分别为加热初始阶段、加热中间阶段和热着火发生阶段。不同阶段存在的主要原因是化学反应和流动的主导作用不同。Abstract: In order to simulate the thermal ignition process of gasoline-air in continuous hot wall, the chemical kinetic model, hydrodynamic model and radiation heat transfer model were coupled to establish a unified model of gasoline-airthermal ignition. According to the working condition of the experiment, the occurrence process of gasoline-air thermal ignition was simulated under the conditions of high temperature induced by continuous hot wall in confined space. Flow field evolution characteristics of the temperature and the pressure were analyzed. The variation curves of temperature, pressure, flow velocity, turbulent velocity and group concentration were obtained at different positions. By simulation, it is found that there are three stages in the process of gasoline-air thermal ignition, namely, the initial heating stage, the heating intermediate stage and the thermal ignition stage. The main reason for the existence of different stages is that the leading roles of chemical reaction and flow are different.
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Key words:
- gasoline-air /
- unified model /
- thermal ignition /
- continuous hot wall /
- chemical kinetic /
- hydrodynamic /
- radiation heat transfer
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表 1 初始组分
Table 1. Initial components
初始组分 质量分数 摩尔分数 摩尔浓度/(mol·cm-3) CH4 0.01 0.018 2 7.45×10-7 C2H6 0.01 0.009 7 3.98×10-7 C3H8 0.01 0.006 6 2.71×10-7 C4H10 0.01 0.005 0 2.05×10-7 n-C7H16 0.01 0.002 9 1.19×10-7 i-C8H18 0.01 0.002 6 1.04×10-7 O2 0.21 0.192 1 7.85×10-6 N2 0.73 0.763 0 3.12×10-5 表 2 热着火过程的6个时间点的基本参数
Table 2. Basic parameters of the thermal ignition process at 6 time points
时间点 t/ms n Tmax/K pmax/Pa vx, max/(m·s-1) vy, max/(m·s-1) I/% No.1 100.09 10 000 452.12 10 484.3 4.93 4.76 280.551 No.2 413.06 63 000 581.78 92 218.8 66.89 52.59 2 435.931 No.3 413.53 64 800 844.91 127 912.0 109.51 55.40 2 812.672 No.4 413.53 80 000 872.86 144 851.9 100.20 42.66 2 266.638 No.5 413.53 100 000 914.99 179 834.6 99.01 40.38 2 195.186 No.6 414.06 587 200 1271.99 381 857.6 306.55 142.44 14 418.030 -
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