摘要
提出采用多孔介质材料制作钝体火焰稳定器,旨在利用其通透和弥散性能改善钝体后燃空比,从而提高火焰稳定性.通过对实心钝体、平均孔径为1.27,mm和0.32,mm的多孔介质钝体尾迹冷态流场、钝体火焰及其稳定特性对比实验,发现基于来流速度和钝体特征长度尺度的雷诺数对实心和多孔介质钝体回流区产生特性影响较大.多孔介质钝体回流区出现在x/D=1,其长度为(0.8～1.0)D,回流强度35%;实心钝体产生的回流区紧贴钝体,长度为1.4D、回流强度为82%.当空气伴流速度为6.0,m/s时,实心钝体燃料流速度小于3.1,m/s时熄火,而平均孔径为1.70,mm和0.32,mm的多孔介质则分别在实心钝体燃料流速度小于1.6,m/s和0.9,m/s后才熄火.由于多孔介质渗透和弥散作用,钝体后燃料空气混合更好,可获得更宽的火焰稳定范围.当燃料速度相同时,多孔介质钝体熄火的空气伴流速度更大;当相同燃料和空气伴流条件时,多孔介质火焰刚性更强,燃烧更充分.
Due to permeability and diffusion, the porous media bluff body was proposed as flame holder to improve flame stability. By comparing of cold flow field, flame structure and flame stabilization of solid, 394 and 1 576 PPM （pores per meter） porous media blunt bodies, it was found that the back flow regions after different bluff bodies changed obviously with Reynolds numbers, which is based on free stream velocity and blunt body length scale. Compared with porous media bodies, the solid blunt body has bigger recirculation regions and stronger back flow intensity. For porous media blunt body, its back flow region occurs at x/D = 1, with about 0.8D---1.0D in length and 35% in back flow intensity. For solid blunt body, however, its back flow region is about 1.4D in length and 82% in back flow intensity. Due to virtual mixing of fuel and oxidant, the porous media flame holder has better flame sta- bilization. For a given fuel velocity, the porous media flame holder has bigger extinction velocity of air co-flow. For the same air and fuel velocities, the combustion after porous media bodies is more stable and effective.
出处
《燃烧科学与技术》
EI
CAS
CSCD
北大核心
2012年第2期111-116,共6页
Journal of Combustion Science and Technology
基金
国家自然科学基金资助项目(11172296
50936005)
