材料期刊网

在低速射流的预混火焰和扩散火焰中都存在火焰闪烁现象。对扩散火焰,其机理已比较明确,是由于浮力诱导引起的一种水力学不稳定性。而对预混火焰闪烁现象则存在水力学不稳定性和热驱动不稳定性两种观点。本文根据水力学不不稳定性观点,把预混火焰的闪烁现象看成是包围火焰锋面的已燃混气层中内、外区间在垂直方向上的相对脉动,应用Kelvin-Helmholtz不稳定性机理进行了分析,获得了火焰闪烁频率与重力和压力的关系式,并与已有的结果作了对比。

Low-speed jet flames are known to flicker at a low frequency. This oscillationsoccur in both premixed and diffusion flames. For diffusion flames the origin andcause of this low-frequency instability are known to be the hydrodynamicinstability induced by the unstable motion of the outer large-scale structuressurrounding the flame front driven by buoyancy effects. But in the case ofpremixed flames, some other views have been proposed, including thehydrodynamic instability as well as heat-driven instability. This paper presentsresults of the hydrodynamic instability analysis for the flicker of premixedflames. Theoretical prediction of the instability frequency as a function ofgravity and ambient pressure has been obtained and is in good agreement withthe experimental results.