Influence of cage lifting piston effect on drift airflow in main intake shaft

In this study,aiming at the piston wind effect caused by cage lifting in main air intake shaft and its influence on air flow in transportation roadway,based on the SST k-ω turbulence model,the dynamic mesh is used to simulate the air fluid during the cage running in the shaft and the simulation data is verified by field measurement. The structural change of the airflow field in the transportation roadway under the influence of the piston wind in the shaft and the turbulence characteristics of the airflow in the roadway are studied. The results show that the piston wind generated by the operation of the cage in the shaft will cause the transient change of the airflow in the flat roadway,leading to the disorder of the airflow field distribution in the roadway and the large disturbance to the local airflow. The trend of probability density curve of wind speed in roadway under the influence of piston wind is a normal distribution. The trend of turbulence intensity along the longitudinal distribution under the influence of piston wind is self-similar,and the overall distribution is exponential. The wind turbulence intensity along the transverse distribution is symmetrically distributed along the roadway center line under the influence of piston wind. In the local position of the roadway,the maximum value of the wind turbulence kinetic energy along the longitudinal distribution is E_max=0.249 m²/s²,and the maximum value of the wind turbulence kinetic energy along the transverse distribution is E_max=0.503 m²/s². The turbulent kinetic energy value is large,which is easy to cause local high and low-speed airflow,eddy current and entrainment of surrounding airflow in the roadway. The mine ventilation system is affected by the unstable factors in the mine,which may lead to the disorder of the local air use location or the whole air flow system. A series of additional effects caused by the frequent lifting of the cage in the main air intake shaft will have a big impact on the ventilation effect of the transportation roadway. The study of the influence of the cage lifting piston effect on the air flow in the roadway provides a reference for supplementing the mine local ventilation theory.