Research and experiment on dust control device with external pneumatic vortex mist curtain for road-header

To effectively control the dust pollution caused by the road-header cutting head rotary breaking,based on the motion law of the high-pressure spray in the vortex gas jet and the secondary atomization fragmentation characteristics, a new type of dust control device with external vortex air mist screen for road-header has been developed,which can prevent high concentration dust dispersion in underground mining area. A scale model of a pneumatic vortex mist cur- tain dust control device including a tunneling system was drawn. Through the numerical simulations,the wind flow field migration law and droplet particle motion law of the device were obtained by using CFD software. An experimental platform was established based on the simulation results,and the atomization performance and dust control performance were obtained by experiment. The simulation results show that a complete rotating air curtain was formed at the front of the ring-mounted air duct. The outer high-pressure spray was impacted by the high-speed vortex rotating airflow,which aggravated the droplet breakage,diffusion and dust-collecting performance of the spray field. The atomization perform- ance experiment results show that the main performance of the mist curtain is determined by the velocity difference be- tween the gas jet and the high pressure spray. When the spray angle is between 45°-75°,the velocity difference be- tween phases is great,and influence of gas jet velocity on atomization performance is dominant. When the spray angle is greater than 75°,the interphase interference decreases and the spray pressure dominates. With the increase of the distance along the direction of flow,the fast attenuation of wind speed leads to the stabilization of droplet motion. The dust-collecting performance experimental results shows that when the spray pressure and the spray angle are constant, when raising the jet velocity alone,the dust collection in front of the vortex mist curtain is poor,and the average dust- collecting rates of dust and respiratory dust are 21. 21% and 26. 24% respectively. At rear of the mist screen,the dust collection rates at different wind speeds are 84. 98% ,87. 88% ,and 90. 70% respectively. The respiratory dust collec- tion rates are 83. 89% ,87. 87% ,and 88. 71% respectively,which shows a better dust control performance than that of traditional high pressure spray.