摘要
根据二维非稳态层流的质量和动量守恒方程,研究强声波作用下煤颗粒周围气体的振荡流动特性.入射波的振幅远大于颗粒特征长度,声雷诺数小于20.根据通用微分方程的解,详细分析不同声雷诺数与斯特劳哈尔数下,颗粒壁面的流场分布、轴向压力梯度、切向应力及分离角的分布,发现在低频(~50 Hz)时,颗粒壁面轴向压力梯度、切向应力及流动分离角的分布主要受曲率效应影响,其变化规律与振荡速度的幅值变化相对应;在高频时(~5 000 Hz),颗粒壁面轴向压力梯度、切向应力及流动分离角的分布同时受到曲率效应和流动加速度的影响.为进一步研究强声波强化煤颗粒燃烧提供理论基础.
To study flow field distribution characteristics around a pulverized coal particle in high intensity acoustic field with sonic frequencies, two-dimensional unsteady mass and momentum conservations for laminar flow in spherical coordinates were developed with actual parameters of power plant boiler. Displacement amplitude of incident sound wave is greater than characteristic length of particles, and acoustic Reynolds number is less than 20. Velocity field, axial pressure gradient, shear stress and flow separation angle around particle were analyzed at different acoustic Reynolds numbers and Strouhal numbers. It is found that axial pressure gradient, shear stress and separation angle are proportional to magnitude of sound at low frequency （ - 50Hz）. However, they are different due to combined effects of curvature and flow acceleration at high frequency （ -5 000 Hz）. It provides theoretical foundation for further research on acoustic enhancement of heat and mass transfer in power plant boiler.
出处
《计算物理》
CSCD
北大核心
2017年第4期425-436,共12页
Chinese Journal of Computational Physics
基金
国家自然科学基金(11474091
11674093和11274111)
河北省自然科学基金(A2015502077)
中央高校基本科研业务费专项资金(2015XS105)资助项目
关键词
强声波
振荡流
煤颗粒
流动分离
high intensity sound
oscillating flow
coal particle
flow separation
