阻塞比对氢-空预混火焰加速影响的可视化研究

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.