掺氢对微尺度空间内预混层流火焰转捩爆燃特性的影响

Effects of Hydrogen Blending Ratio on the Characteristics of Deflagration Transition for Laminar Premixed Flame in a Micro-Scale Space

针对基于燃烧的微小型动力装置存在燃烧效率低、火焰传播速度慢的问题,设计了一个可视化的、特征间距仅为0.45 mm的微尺度定容燃烧室,实验比较了0~1的掺氢比例下,丙烷/氢气/空气预混火焰在该燃烧室内的传播以及加速过程.实验发现没有掺氢时,丙烷/空气预混火焰需要在0.25 MPa初始压力下才能够传播;当掺氢比例为0.2时,火焰在传播过程中会发生从缓燃到爆燃的转变,这种燃烧模态的转变可以大幅缩短燃烧室内火焰传播时间,极大提升火焰传播速度.实验还发现掺氢比例以及初始压力的提升均能使得微尺度火焰传播速度提升.

Aimed at the problems of low combustion efficiency and low flame propagation speed in micro-scale power devices which utilize combustion,a visualized constant-volume combustion chamber was fabricated,of which the characteristic length was as small as 0.45 mm.Propane/hydrogen/air mixture was adopted in the experiments and the hydrogen blend ratio was changed from 0 to 1.The flame propagation behavior and the flame acceleration were investigated.The experimental results show that the propagation of propane/air flame required an initial pressure of at least 0.25 MPa.When the hydrogen blending ratio was 0.2,the transition from slow combustion to deflagration occurred in the process of flame propagation.The conversion of the combustion mode greatly shortened the flame propagation time in the combustion chamber and remarkably increased the flame propagation speed.Moreover,the increase of hydrogen blending ratio and the initial pressure were significantly beneficial to the enlargement of flame propagation speed.