Abstract:

Based on WALE model and Zimont premixed combustion model, a large eddy simulation(LES) had been applied to study the characteristics of flame of gasoline-air mixture explosions in a closed narrow-long space with an inner size of 0.187 m×0.187 m×2 m. The results of large eddy simulation and RNG k-e model were compared to experimental data and the comparisons confirmed that LES is capable to simulate gasoline-air mixture explosions in closed narrow-long space. The conclusions show that:(1) LES accurately reproduced the formations of flame structure throughout propagation. (2) Two kinds of symmetrical vortices in opposite direction were created in the burned region after the flame front. The kind of symmetrical vortices near the pipe surface contributes to the formation of Tulip flame and the opposite symmetrical vortices that come after the flame further propagation contributes to the collapse of Tulip flame. (3) At the normal concentration of gasoline-air mixture explosion, the gas flow remains positive in the unburned zone and the explosion overpressure, the flame propagation speed and the flame structure have significant coupling relation.

Key words: closed space, gasoline-air mixture, numerical simulation, overpressure, flame characteristics

摘要：

基于WALE模型和Zimont预混火焰模型对横截面尺寸0.187 m×0.187 m，长2 m的狭长密闭空间内汽油-空气混合物爆炸火焰特性进行了大涡模拟。将大涡模拟与RNG k-e湍流模型计算结果及实验结果进行对比，验证了大涡模拟对于狭长密闭空间中汽油-空气混合物预混爆炸计算的适用性。结果表明：（1）大涡模拟准确再现了火焰传播过程中的形态变化；（2）火焰锋面后已燃区壁面两侧和中轴线两侧涡旋结构分别对Tulip形火焰的形成和消散有显著影响，且形成及消散前的两种涡旋结构方向相反；（3）当量比浓度下汽油-空气混合物爆炸未燃区气体流动始终保持正向传播，且爆炸超压、火焰传播速度和火焰传播形态三者间存在显著的耦合性。

关键词: 密闭空间, 油气, 数值模拟, 超压, 火焰特性