旋风分离器内颗粒轨迹的数值模拟

采用数值模拟的方法研究旋风分离器内的颗粒运动:对单相流场采用湍流各向异性的雷诺应力模型,对气、固两相流场采用相间耦合的随机轨道模型;通过描述颗粒的运动轨迹,揭示了颗粒在旋风分离器中运动的物理机制.结果表明:颗粒的运动轨迹比较复杂,且带有很大的随机性;尤其是小粒径颗粒,受气流湍动影响显著,即使是粒径、入射位置相同,其运动轨迹也各不相同,最终的位置也不同;小粒径颗粒更容易受二次涡流影响,从而降低分离器的效率;另外,还模拟出了上灰环、排气管短路流及排尘口返混等影响分离效率的几种现象,为进一步研究旋风分离器的分离机理理论及实验研究打下基础.

Numerical Simulation of the Paticles' Track in a Cyclone Separator

The movement of particles in a cyclone separator has been studied by numerical simulation. We adopt the Reynolds stress model for the single-phase and the coupling discrete random walk model for the two-phase. The physical mechanism for the movement of particles in a cyclone separator is revealed by describing the particles' tracks. The results show that the particles' movement is more complex and random. The small particles are easily influenced by turbulence, and their tracks and finally positions are different even if their diameters and first positions are the same. The small particles are more easily influenced by the second vortex so that they reduce the separating efficiency. We have also predicted the phenomena affecting the separation efficiency--the up ash loop, the short circuit of exhaust duct and the return confusion of eject dust duct. All this makes for a better understanding of the separation mechanism of cyclone separator, and forms the basis for the further theory and experiment study on the cyclone separator.