颗粒粒径对旋流燃烧器出口流场作用的实验研究  

Experimental study on the effect of particle size on the exit flow field of a swirl burner

作　　者：王卫良[1] 崔凯[1] 张海[1] 汤根土[1] 杨海瑞[1] 吕俊复[1] 

机构地区：[1]清华大学热能工程系热科学与动力工程教育部重点实验室,北京100084

出　　处：《中国科技论文在线》2010年第11期840-845,共6页

基　　金：国家高技术研究发展计划(863计划)资助项目(2007AA05Z303);日本IHI公司的资助

摘　　要：经由燃烧器送入锅炉炉膛的煤粉具有一定的粒度分布,并常发生变化,了解粒径对燃烧器出口流场的作用,对设计和运行燃烧设备有重要意义。在旋流燃烧器的冷态实验台上,观察固体的浓度分布,并且使用激光粒子成像测速仪(PIV)测量了不同示踪粒子粒径下燃烧器出口速度场。试验结果表明,颗粒粒径可以明显地影响燃烧器出口流场特性,小颗粒对应的浓度场湍动度大,一次风中的颗粒容易被二次风卷吸而后向外扩散。随着颗粒粒径加大,颗粒受到旋流二次风的作用减弱,相反主流气流受颗粒径向运动的干扰增强,旋流强度减弱,中心回流区向下游推移,主流气流卷吸炉膛烟气的能力减弱。颗粒粒径增大时,同一出口平行截面的气体轴向和径向速度均有所增加,对轴向速度的变化作用较对径向速度的强,在试验范围内射流扩展角基本不变。Since the coal particles sent into the furnace of a boiler through the burner are of a size distribution and often vary in a certain size range during operation,understanding the particle size effect on the flow field is significant for burner design and operation.Experimental studies were carried out in a cold rig equipped with a swirl burner.The particle concentration field was observed by a CCD camera and the velocity field out of the burner exit was measured by a particle image velocimetry（PIV）,under different seeding particle sizes.Experimental results show that the particle size can remarkably affect the gas-solid two-phase field outside the burner.The smaller particles easily follow the main gaseous flow stream and thus intensively mix into the secondary air and expand the main flow mixture with intensive turbulence.The larger particles,with larger inertia,more intend to keep the initial motion and are less influenced by the strongly swirling secondary air.On the other hand,the influence of solid phase of larger particles on the main flow stream becomes stronger when the particles pass through the swirling secondary air,reducing the swirling intensity of the secondary air.As a result,the recirculation zone becomes smaller,and its center moves further downstream.With the increment of particle size,both the axial velocity and the radial velocity slightly increase.Within the experimental circumstance,the effect on axial velocity is slightly stronger while expanding angle of the secondary air keeps nearly the same.

关 键 词：多相流动 颗粒粒径作用 PIV测量 旋流燃烧器 出口流场 

分 类 号：TK223.23[动力工程及工程热物理—动力机械及工程]