Experimental And Numerical Study Of Dynamic Characteristics Of Flow Field In Cyclone Separator

Cyclone separator is widely used in industrial production because of its simple structure,high separation efficiency and continuous operation.The flow field in cyclone is very complex and has obvious dynamic characteristics,which mainly shows swirling instability,that the flow field parameters change with time.The instability affects the particles diffusion,reduce the separation efficiency of the cyclone separator,and influence the performance of the device with cyclone.Therefore,it is of great significance to study the dynamic characteristics of the flow field in the cyclone separator for improving the performance of the cyclone.In this paper,the fluctuation of pressure at different positions of strong flow field in cyclone is investigated by means of experiment and numerical simulation.This study compares the prediction of two numerical simulation methods,probes into the source of the pressure fluctuation,depicts the trajectory of the vortex core center,and analyzes the influence of the change of the inlet velocity on pressure fluctuation in the flow field.The results show that the pressure fluctuation in the central region of the flow field is larger than that in external region.The pressure fluctuation has two main frequencies,one appears in the cone bottom center as well as the upper center area of the dust hopper,the other exists whole space in the flow field.The former,local frequency,is caused by the rotation of the vortex core center around the geometric center of the cyclone separator,which presents the characteristic of quasi periodic fluctuation.The latter,total space frequency,is also caused by the rotation of the vortex core center,but it does not necessarily revolve around the geometric center and is not synchronized with the rotation of the vortex core at the cone bottom.The higher the inlet velocity,the more intense the pressure fluctuation.The total space frequency doesn’t change with the inlet velocity,while the local frequency will increase linearly with the inlet velocity.At the same time,the distribution area of local frequency will be enlarged with the increase of the tone speed.These frequencies of flow field in cyclone separator are related to Reynolds number.The numerical calculation of the flow field shows that the prediction accuracy of the large eddy simulation is higher than that of Reynolds stress model in the flow field asymmetry,secondary vortices and pressure fluctuation.The results of the study further improved the understanding of the instability of the flow field in cyclone separator.