【作者】 许胜；

【导师】 刘明侯；

【作者基本信息】 中国科学技术大学 ， 热能工程， 2011， 硕士

【摘要】 在航空涡轮及火箭冲压发动机、回转窑等燃烧室中,由于来流空气速度较大,导致火焰不稳定。工程中常用V型实心钝体形成稳定的回流区来稳定火焰。然而大量的研究和应用表明,V型实心钝体火焰稳定器可导致燃烧室内较大流动损失,且火焰稳定边界相对较窄,燃烧效率不高,还容易出现振荡燃烧。本文提出用多孔材料代替实心钝体制作多孔介质火焰稳定器。其多孔空间结构,大比热容及大比表面积,可有效减少流动损失,有助于火焰稳定。本文主要对比试验研究多孔介质钝体与实心钝体尾迹差异,探究用多孔介质钝体稳定火焰的可能性。主要工作包括:(1)在低速条件下用DPIV(Digital Particale Image Velocimetry)系统实现了对粒子的速度分布测量功能。由相同工况钝体尾迹速度矢量图,流函数图,以及涡量场可直观观测到实心钝体和多孔介质钝体尾迹流场的差异。(2)回流区的大小和位置决定了钝体下游高温燃气预热新鲜燃料和空气混合的能力,本文利用二维热线测量相同工况下不同钝体尾迹平均速度场,雷诺应力等,进一步探索钝体尾迹回流区结构。并在冷态流场中测量不同钝体的流阻损失。(3)用丙烷作燃料观测不同钝体随着工况变化火焰高度,火焰结构演变过程,测试钝体对熄火极限的影响,以及通过火焰图像进行温度定量化处理来研究钝体火焰燃烧静态特性。基于上述比较,得出结论如下:(1)实心钝体回流区靠近钝体,回流区范围和回流强度较大;多孔介质钝体回流区状况与孔密度有关,总的来说其回流区范围以及回流强度较实心钝体弱,回流区的位置与向下游移动。(2)在大堵塞比燃烧室内,采用多孔介质钝体可在大大降低流阻。(3)实心钝体堵塞尾迹强剪切可强化混合,但易导致熄火。多孔介质火焰稳定器的通透与弥散性能通过改变钝体后燃空比可拓宽火焰熄火极限。更多还原

【Abstract】 In aviation turbine engines, rocket ramjet, rotary kiln and other combustion chambers, the high-speed air flow frequently cause flame instability. V-solid bluff body was used to form a stable recirculation zone to stabilize the flame in the actual application. However, a lot of research and application show that, in combustion chamber, this kind of flame stabilizer can lead to large flow loss and narrow the flame stability boundary, decrease the combustion efficiency, prone to generate oscillating combustion. In this paper, the porous media was investigated to make flame holder instead of solid bluff body. The special space structure, large specific heat and specific surface area of porous media can reduce the flow loss effectively, stabilize the flame.Based on the comparative trials of porous media and solid bluff body, the possibility of using porous media bluff-body to stabilize flame was reseached. The main research works of this paper are focused on following areas:(1) In low-speed flows, a DPIV(Digital Particale Image Velocimetry)system was used to measure the velocity distribution. At the same flow condition, the differences of wake flow of porous medium and solid bluff body can be observed by average velocity field, stream function graph and vorticity field.(2) The size and position of recirculation zone depend on the capability of preheating fresh fule and air mixing by high-temperature fuel in the downstream of bluff body.更多还原