摘要
根据二维轴对称、非稳态、层流的质量、动量和能量守恒方程,研究了强声波作用下夹带在烟气中单颗粒煤粉的传热特性.分析了声压级为145~167dB,频率f分别为50 Hz、1 000 Hz和5 000Hz时,颗粒壁面的温度场、局部努塞尔数、表面平均努塞尔数及时间-空间平均努塞尔数的分布.结果表明:当f=50Hz时,颗粒壁面流场主要受到曲率效应的影响,努塞尔数随着振荡速度幅值的增大而增大;随着频率的增大,流动加速度的作用逐渐加强,当f=5 000Hz时,热边界层与流场之间出现了相位迟滞;不同频率时颗粒的努塞尔数相差不大,时间-空间平均努塞尔数的最大差值比为2.82%;当声压级为167dB,f=5 000Hz时,颗粒的时间-空间平均努塞尔数是无声场时的1.78倍.
Heat transfer characteristics around single coal particles entrained by flue gas under the action of high intensity acoustic field were studied based on two-dimensional,unsteady and laminar equations for mass,momentum and energy conservation and transport,so as to analyze the temperature field,local Nusselt,surface-averaged Nusselt and space-and time-averaged Nusselt numbers around the coal particles at the sound pressure level（SPL）varying in 145-167 dB and at frequencies of 50 Hz,1 000 Hz and 5 000 Hz,respectively.Results show that at 50 Hz,the flow field around coal particles is mainly affected by curvature effects,and the Nusselt number increases with the rise of amplitude of oscillation velocity;with the rise of frequency,the effect of flow acceleration increases,and phase lag would appear between the thermal boundary layer and the oscillating flow field at 5 000Hz;the combined effects of curvature and flow acceleration result in the maximum difference of 2.82% in the space-and time-averaged Nusselt number at dif-ferent frequencies,i.e.little difference of Nusselt number;the space-and time-averaged Nusselt number is 1.78 times of that without acoustic field at 167 dB and 5 000 Hz.
作者
许伟龙
姜根山
安连锁
刘月超
XU Weilong JIANG Genshan AN Liansuo LIU Yuechao(School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China Department of Mathematics and Physics, North China Electric Power University, Baoding 071003, Hebei Province, China)
出处
《动力工程学报》
CAS
CSCD
北大核心
2017年第10期788-795,共8页
Journal of Chinese Society of Power Engineering
基金
国家自然科学基金资助项目(11474091
11674093
11274111)
河北省自然科学基金资助项目(A2015502077)
关键词
强声波
传热特性
局部努塞尔数
表面平均努塞尔数
时间-空间平均努塞尔数
相位迟滞
high intensity acoustic wave
heat transfer characteristics
local Nusselt number
surface-averaged Nusselt number
space-and time-averaged Nusselt number
phase lag
