封闭空间中不同压力下火焰过孔板加速机理研究

爆震或超级爆震发生时总会伴随着湍流火焰-冲击波相互作用，对其开展研究是揭示爆震或超级爆震机理的关键，研究火焰加速产生压力波的过程是火焰-压力波相互作用研究的基础性前提。基于自主设计的定容燃烧弹和Converge三维数值模拟方法，对封闭空间中火焰过孔板加速机理及影响因素开展了研究，讨论了初始压力对火焰过孔板加速的影响。依据火焰传播形态与速度，将火焰过孔板加速过程分为3个阶段:层流火焰阶段、射流火焰阶段和湍流火焰阶段。通过分析火焰过孔板过程中的流场情况，发现在火焰未到达孔板前，孔板附近存在强射流，火焰受强射流的驱动而急剧加速；但当火焰穿过孔板之后，火焰锋面前的流场速度沿着远离火焰的方向而逐渐下降，说明开始由火焰驱动未燃气体运动。比较不同压力下的火焰过孔板过程，发现湍流火焰传播速度和缸压振荡均随着初始压力的提高而升高。

Experimental and numerical investigations of flame acceleration after passing through a perforated plate in a confined space

Essentially, the engine knock or the super-knock is always accompanied by the interactions between the turbulent flame and the shock wave, with rapid chemical energy release. Thus, it is of great significance to investigate the interactions between the turbulent flame and shock waves which is the key to reveal the mechanism of the knock or super-knock. And the flame acceleration inducing pressure waves is the basic premise for the study of flame-shock interactions. Based on a self-designed constant volume chamber and 3-dimensional numerical simulation by Converge, the mechanism and impact factors of the flame acceleration after passing through the perforated plate are investigated. In addition, the influence of the initial pressure on the combustion phenomenon is discussed. According to the flame morphology and the flame tip velocity, the evolution of the flame acceleration is divided into three stages, which are the laminar flame stage, the jet flame stage and the turbulent flame stage. The flow field results show that there exists a strong jet flow at the perforated plate before the flame reaches, which drives the flame acceleration. However, after the flame passes through the perforated plate, the flow velocity downstream of the flame front decreases as it departs from the flame, which means the flow is driven by the flame. In addition, it is found that the turbulent flame velocity, pressure and pressure oscillation increase with the increase of the initial pressure.