Abstract:

Cylinder diameter is the core of cyclone separator size optimization, but different results are reported in the literatures on its effect on performance, and its flow field mechanism is rarely explored. In this study, under the conditions of controlling the inlet size of 145 mm × 63 mm, the inlet gas velocity of 27.5 m/s, and the other dimensions are proportional to the cylinder diameter, the effect of cylinder diameter on performance is investigated through performance tests; and the flow field mechanism is explored using computational fluid dynamics (CFD). The results show that the pressure drop decreases with increasing cylinder diameter, and the decrease in tangential velocity is the main cause. The separation efficiency increases and then decreases with the increase of cylinder diameter, and the optimum efficiency is about 410 mm. The flow field analysis shows that it is related to the following mechanisms: the tangential velocity and axial velocity of the airflow in the separator decrease with the increase of cylinder diameter, but the axial velocity decreases more, and the stagnation phenomenon occurs in a large cylinder diameter, and both of them work together to make the secondary separation capability of the internal cyclone for small particles increase with the increase of cylinder diameter. Therefore, the mixing escape rate is reduced. After increasing the cylinder diameter, the upward flow area expands, and the strong radial convergence at the exhaust pipe mouth has an impact on the upward flow, causing particles to escape by short-circuiting and at the same time also aggravating the escape of the particles held by the internal cyclone, and the amount of escape decreases with the increase of the cylinder diameter, and then increases, with the lowest at the optimal cylinder diameter. Increasing the cylinder diameter will make the exhaust pipe outside the formation of airflow barrier, particle short-circuit escape more difficult, but too much increase in the cylinder diameter will cause an increase in the short-circuit flow.

Key words: cyclone separator, two-phase flow, computational fluid dynamics, cylinder diameter, performance

摘要：

筒体直径是旋风分离器尺寸优化的核心，但关于其对性能的影响，文献报道了不同结果，且鲜有探讨其流场机制。在控制入口尺寸为145 mm×63 mm，入口气速为27.5 m/s，其他尺寸与筒径成一定比例的条件下，通过性能测试研究筒径对旋风分离器性能的影响；利用计算流体力学（computational fluid dynamics， CFD）探索流场机制。结果表明，压降随筒径增加而减小，切向速度的降低是主因。分离效率随筒径增加而先增后减，最佳效率筒径约410 mm。流场分析表明其与以下机制有关：分离器内气流切向速度和轴向速度随着筒径的增加而降低，但轴向速度降幅更大，且在大筒径中产生滞留现象，二者共同作用使内旋流对微小颗粒的二次分离能力随筒径增加而提高，返混逃逸率因此降低。筒径增大后，上行流区域扩张，排气管口较强的径向汇流对上行流产生影响，造成颗粒短路逃逸的同时也加剧了内旋流所持颗粒的逃逸，逃逸量随筒径增加而先减小后增大，最佳筒径处最低。增大筒径会使得排气管外形成上行流屏障，颗粒短路逃逸难度增大，但过分增加筒径会造成短路流量增加。

关键词: 旋风分离器, 两相流, 计算流体力学, 筒体直径, 性能