摘要
颗粒运动特性是深入理解颗粒弥散和气固混合的关键,采用粒子图像测速仪(PIV)对不同收缩射流颗粒运动行为进行了研究;考察了喷嘴收缩角(α=20o,40o,60o,80o)和气体射流速度对颗粒轴向速度、径向速度和相干涡结构的影响。结果表明:与无收缩直管射流相比,喷嘴收缩效应使射流近场气固相间存在较大的轴向滑移速度,颗粒做加速运动。喷嘴收缩产生径向速度分量,使颗粒向射流轴线聚集,形成斜向撞击流,促进了射流动量由轴向向径向的转化。径向速度分量随喷嘴收缩角的增大而增大。气体射流速度增加,颗粒速度的滞后性和相间弛豫时间延长,加速区下移。喷嘴收缩加剧了射流剪切层的不稳定性,促使剪切层振荡卷起形成大尺度和高涡量的轴对称涡环。
The particle dynamics of the gas-particle two-phase contraction jets were investigated to understand the particles dispersion and gas-particle mixing using the particle image velocimetry(PIV). The effects of nozzle contraction angles(α=20o, 40o, 60o, 80o) and gas jet velocities on the axial and radial velocity components of the particles and coherent vortices structures were discussed in a confined reactor. Compared with the pipe jet(without contraction), the nozzle contraction effect was found to result in a considerable axial slip velocity between particle and gas phase, which in turn accelerated the movement of particles. The radial velocity component formed due to nozzle contraction and increased with the contraction angle, made particles gather towards the jet axis, forming a diagonal impinging stream, which enhanced the momentum transformation from axial to radial directions. With the increase of gas jet velocity, the lag of particle velocity and interphase relaxation time increased, and the acceleration region moved towards downstream. The nozzle contraction intensified the instability of the shear layers, which made the shear layer oscillate and roll up to form axisymmetric vortex rings with large-scale and high-vorticity.
作者
巴忠仁
贾风辉
赵建涛
聂伟
郝振华
房倚天
BA Zhong-ren;JIA Feng-hui;ZHAO Jian-tao;NIE Wei;HAO Zhen-hua;FANG Yi-tian(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Zi Bo School of Technology,Zibo 255100,China)
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2022年第5期656-664,共9页
Journal of Chemical Engineering of Chinese Universities
基金
山西省科技重大专项(20201102006)
山西省重点研发计划(201903D121018)
国家重点研发计划(2018YFC0808500)。
关键词
气固两相射流
喷嘴结构
气固混合
相干结构
粒子图像测速仪
gas-particle two-phase jet
nozzle configuration
gas-particle mixing
coherent structures
particle image velocimetry(PIV)
