Abstract:

Particle precipitation in duct flow is important in particle industry and HAVC. There are various duct geometries in industry, but most experiments in the literatures were conducted on smooth ducts. In the present study, a rectangular duct with a series of staggered baffles being installing inside was set up. Power plant ash and CaCO₃ particles were sprayed into the air flow through the duct. The measurement showed that the baffles significantly increased the particle precipitation by orders of magnitude, which was consistent with the modeling results in the literatures. By greasing the baffle surfaces, the reflection of particles on the surfaces were repressed and thus precipitation was enhanced by a limited amount. The results showed that the baffle structures have critical influence on the fine particle deposition while the baffle surface property may not be a significant factor.

Key words: fine particle, turbulence, precipitation, wall, baffled flow

摘要：

微细颗粒物在管内的沉积现象发生于各类颗粒输运、通风系统、烟气管道积尘过程。实际过程中有各类复杂的管道情况，然而现有研究多针对的是光滑管道。对带有扰流挡板的管道内微细颗粒物沉积进行实验探究。搭建了带有系列扰流挡板的湍流管道系统，研究粉煤灰和碳酸钙颗粒在各类条件下的沉积情况。实验获得带扰流挡板的管道的沉积效率，发现其数量级高于光管，与文献中的模型研究结果一致。实验进一步在挡板涂抹油脂，发现其抑制颗粒物在壁面上的反弹，使得沉积效率得以少量提高；同时也说明，限制微细颗粒沉积的主要瓶颈在于其流场跟随性强从而无法有效到达挡板壁面，而不是其在壁面上的反弹。实验结果证明管道中的挡板结构对颗粒物沉积产生重要影响，挡板壁面属性为次要因素，结论可为相关积尘、除尘工业管道设计提供重要参考。

关键词: 细颗粒物, 湍流, 沉积, 壁面, 扰流