Effects of forced-to-exhaust ratio of air volume on dust control of wall-attached swirling ventilation for mechanized excavation face

Wall-attached swirling ventilation is a new type of ventilation for the mechanized excavation face. The dust control effect of the wall-attached swirling ventilation is affected by the forced-to-exhaust air volume ratio. In order to investigate the influence of the air volume ratio on the dust control effect of mechanized excavation face, art experimental model of the wall-attachment swirling ventilation for mechanized excavation face was developed as a reduced scale representation of the D04 mechanized excavation face in Dong Huai Coal Mine of Guangxi Baise Baikuang Group Co., Ltd. Based on this model, the airflow field and dust control of mechanized excavation face at different forced-to-exhaust ratios was analyzed using the study equipment including particle image velocimetry (PIV) system, FCC-25 explosion-proof dust sampler, LS 13320 laser diffraction particle size analyzer, and etc. The analysis results showed that the air velocity at the front end of air supply tube in the wall-attached swirling ventilation was small, the disturbance to the dust production at the heading end by the air flow was weak, and the dust dispersion ability was weak at the front end. In the wall-attached swirling ventilation, both radial air curtain and axial air curtain were generated and pointing to heading end. The cooperation effect of both air curtains controlled dust in the heading area. Thus the operating area for the driver was kept clean and fresh when wall-attached swirling ventilation was running, which ensured a healthy working environment for the roadheader driver. The dust control effect of wall swirling ventilation depended on not only axial air curtain but also radial air curtain. If the forced-to-exhaust ratio was increased, on one hand, the disturbance on the flow field was larger and the intensity of the axial air curtain in the heading end area was weaker; on the other hand, the intensity of the radial air curtain and the dust separation ability were enhanced. When the forced-to-exhaust ratio was 0.8, the wall-attached swirling showed the best dust control effect, the concentration of both the full dust and the respiratory dust around the driver was the lowest, and the separation efficiencies for the full dust and respiratory dust were the highest, which were 93.64% and 98.18%, respectively.