摘要
利用CFD技术模拟研究了排气管结构对矩形进口方形旋风分离器的阻力和分离特性的影响机理。其中气相模型采用雷诺应力湍流模型(RSM),颗粒相采用随机轨道模型。首先将计算结果与实验数据作对比,表明模型计算结果可靠。结果表明,分离器内部排气管和分离器壁面间的区域为强旋湍流区,靠近分离器壁面和排气管壁面的区域旋流强度较弱。方形的排气管结构使方形旋风分离器的效率提高而阻力降低。其原因是改变排气管的结构影响分离器内的流动特点和湍动能的分布,从而影响了分离效率和阻力损失。排气管下方的分离器锥体区域出现回流,排气管为圆管时回流的范围和速度较大,导致小颗粒易于随气流向上运动进入排气管逃逸,使分离效率较小;且排气管为圆管时分离器内的湍流动能也较大,是造成阻力损失较大的原因。合理设计分离器的出口结构以改变分离区的湍动能分布是减小能量损失的着眼处。
In this paper, we are going to present a CFD numerical simulated model on the effect of gas exhaust configuration on the pressure drop and separation efficiency of a square-type cyclone separator. In conducting our research, we applied Reynolds Stress Model （RSM） to simulate the turbulent flow of gas phase and a random trajectory model to simulate the particle motion. Comparing the numerical results on velocity, grade separation efficiency and pressure drop with the experimental data, the present model and the numerically simulated method are beth fit for the simulation of the separator. The numerical results also show that the flow field in the cyclone includes a strong swirling region between the exhaust exit and the separating wall with a weak swirling region near the separator wall. The results of our experiments also indicate that the separation efficiency could be increased with the pressure drop decreased when the gas exhaust configuration changed from a circular tube to a square duct with the same cross section. The chief cause leading to the change is that the gas exhaust configuration did influence the distribution of the reirculation and the local turbulent kinetic energy of the gas phase remains below the gas exhaust inlet inside the cyclone. When the gas exhaust configuration is a round tube, the re-cireulation would take more space and the upward velocity tends also to be higher than those when the gas exhaust configuration is a square duct, which made the small particles move up to the gas exhaust exit and then run out into the open air. The local turbulent kinetic energy of the gas phase also proves higher for a circular gas exhaust than that for a square-shaped outlet exhaust. Since the turbulent movement takes up the energy from the main air current, it would lead to the drop of the pressure. Therefore, a reasonable design of the gas exhaust configuration is the key to achieving a square cyclone separator with low pressure drop and high separation efficiency.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2009年第4期32-37,共6页
Journal of Safety and Environment
关键词
热能工程
循环流化床
方形旋风分离器
出口结构
thermal engineering
circulating fluidized bed
square cyclone separator
gas exhaust configuration
