低热值气体燃料掺氢火焰稳定性的研究

Study on flame stability of hydrogen blended low calorific value gases

基于直接数值模拟方法和详细化学反应机理研究了流体动力学不稳定性和热-质扩散不稳定性共同作用下的低热值气体燃料掺氢胞状火焰的发展和演变过程.建立了多组分气体燃料燃烧控制方程,获得了不稳定性作用下的低热值气体燃料掺氢胞状火焰的多种演变形式:胞的分裂、局部熄灭、二次熄灭和再燃.研究结果表明随着燃料中H2的增加,胞状火焰出现的时间提前,火焰胞的幅值增加.随着燃料中CO2的增加,火焰的不稳定性受到抑制.低热值气体燃料掺氢火焰在不稳定时会出现火焰胞的分裂、局部熄灭和再燃等3种动力学形态.胞的二次熄灭只发生在热-质扩散不稳定性较强的稀燃H2/空气火焰中.

The development and evolution of the cellular flames of H2 blended low calorific value（LCV）gas under coupled hydrodynamic and diffusional-thermal instabilities were investigated based on the direct numerical simulation（DNS）approach and the detailed chemical mechanisms.The governing equations of gas fuel combustion including multiple species diffusion factors were established.The regimes of cellular flame of LCV gas under the influence of instabilities were obtained,including cell splitting,local extinction,secondary extinction and reburning.The results show that an early onset of cellular flames is observed,and the amplitudes of cellular flame front increase with the increase of H2 in fuel/air mixtures.The cellular instability is suppressed with the increase of CO2 in fuel/air mixtures.Cell splitting,local extinction and reburning of cellular flames occur in LCV gas fuel with high H2 fraction under the influence of instabilities.The secondary extinction of cellular flames only occurs in lean H2/air flames under strong diffusionalthermal instability.