Particle Image Velocimetry of a Swirling Fluidized Bed at Different Blade Angles

The particle motion within a stable swirling operation regime of a fluidized bed is investigated. Particle image velocimetry was used to elaborate the hydrodynamics of multi‐sized particles fluidized at different air distributor blade angles. The experimental results revealed that the superficial velocity is the most prominent aspect affecting the hydrodynamics of a swirling fluidized bed (SFB) followed by the bed weight, particle shape, and blade inclination angle. Particles of different sizes and shapes fluidized well in the SFB which emphasizes its superiority over contemporary techniques. The slug‐wavy regime in the SFB is promising and has considerable potential, especially for diffusion‐controlled reactions and processes in the industry. The particle velocity increased with air flow rate at shallow bed height but decreased with bed weight.     

Effect of Particle Image Velocimetry Setting Parameters on Local Velocity Measurements in an Agitated Vessel

Although they are obtained under the same conditions, results on the flow field in an agitated vessel achieved using particle image velocimetry (PIV) may vary due to differences in the PIV conditions. The influence on turbulence characteristics of the main PIV setting parameters, i.e., PIV spatial resolution, sampling frequency, and recording time, was investigated. Tests were performed with three different liquids in a developed turbulent field for a Rushton turbine impeller using two‐dimensional time‐resolved PIV. To obtain the relevant velocity gradients, a minimum recording time is needed. No effect of sampling frequency was observed if the sampling frequency was higher than approximately 17 times the impeller frequency, which is about three times the impeller blade frequency.     

T型撞击流混合器内流动特性的PIV研究

采用粒子图像测速技术对入射管直径为3 mm、混合腔直径为16 mm的T型撞击流混合器内的流动特性进行了研究,考察了不同流速比和撞击轴线上方空间条件下混合腔内的速度和湍流动能分布. 结果表明,在相同入射管直径和流速下,撞击驻点位于混合腔中心处,无因次化的速度和湍流动能分布趋势基本一致. 高湍流动能区主要集中在撞击点附近区域,其无因次化数值是传统Rushton涡轮搅拌槽叶端处的3倍. 流速比对撞击驻点位置影响显著;减小撞击轴线上方空间可增加高湍流动能分布区域,利于物料混合.