非等温边界层中相间相互作用实验研究

Investigation of interactions between phases in gas-solid temperature boundary layer by experiments

应用三维粒子动态分析仪 ( PDA) ,测量了水平流动非等温边界层中气固两相间相互作用的特性 .结果表明 ,颗粒使气流温度边界层变薄 ,强化了壁面与气流间的传热 ;颗粒质量流率对相间作用有较大影响 ,随颗粒流率的增加 ,颗粒对气流平均速度和湍流的影响增大 .颗粒和气流相互作用在不同方向上呈各向异性 ;颗粒对气流垂直方向的脉动影响较大 ;颗粒改变了气流雷诺应力在壁面附近的分布 ,对湍流的拟序结构产生了较大的影响 .

The interactions between air flow and particles have been investigated with a three dimensional particle dynamics analyzer(PDA) for the gas solid two phase flow in a horizontal temperature boundary layer. Effects of introduction particles with nominal diameter of 230 μm at two different particle mass loading ratio on the air flow boundary layer were examined. The turbulence modification due to the addition of particles was compared at different cross sections along the flat plate. The experimental results show that the particles have significant effects on the statistic characteristics of the boundary layer. Though the mean velocity of the air flow was not distinguishably changed, augments in the root main squared fluctuation velocity were observed in both directions, the streamwise and the vertical direction. As the particle mass loading ratio is increased, the modification effects on turbulence in the boundary layer are more significant. In the case of high load ratio, the change of turbulence in the vertical direction is more considerable than that in the streamwise direction. The Reynolds stress profile near the wall is also changed due to the particles, therefore the imitate order of turbulence is influenced.