阻塞比对氢-空预混火焰加速影响的可视化研究

Visual Research on Effect of Blockage Ratio on Premixed Hydrogen-Air Flame Acceleration

在顶置点火定容燃烧弹内布置网孔板,通过火焰传播路径上的孔板诱导实现火焰加速。利用纹影法和压力采集系统,研究了阻塞比对氢-空预混气孔板诱导火焰加速的影响规律。试验结果表明:阻塞比的增加可增大孔板对火焰的扰动,使火焰传播速度大幅增加;任意初始工况下均存在一个最佳阻塞比使燃烧持续期达到最短,在试验范围内,较低初始压力、较小当量比和较高初始温度的最佳阻塞比为0. 90,其余工况的最佳阻塞比均在0. 84;孔板诱导燃烧加速的效果非常显著,在试验工况范围内,各阻塞比孔板诱导下的燃烧持续期均缩短45%以上。

Flame acceleration was to be induced by an orifice plate located on the flame propagation path. A set of orifice plates with different blockage ratios was arranged one for each time in a constant volume combustion chamber with a spark at the top;with Schlieren and a pressure acquisition system the influence was experimentally analyzed of different blockage ratios on the flame acceleration when premixed hydrogen-air flame traversed an orifice plate. The results show that an orifice plate with increased blockage ratio can enhance the disturbance of flame;as a result the flame propagation speed is dramatically promoted. There is an optimal blockage ratio at any initial condition, with which the combustion duration is shortest. In the testing range, the optimum blocking ratio at low initial pressure, low equivalent ratio and high initial temperature is 0.90, while the optimum blocking ratio at other conditions is 0.84. The effect of an orifice-plate on the flame acceleration is extremely remarkable. Within the experimental conditions, the combustion durations with orifice plates of different blockage ratios are shortened by more than 45% compared with those without an orifice plate.