Optimization analysis of dust field under comprehensive control of air outlet and exhaust air flow in fully mechanized excavation face

There is an urgent need to address the safety problems caused by unreasonable airflow distribution and seri⁃ ous dust accumulation in mine roadway. Therefore，this paper attempted to achieve an effective dust reduction via ana⁃ lyzing and determining the airflow state of roadway，and varying the airflow distribution. The four parameters were se⁃ lected，namely，the outlet diameter，the right angle of outlet，the exhaust vent diameter and the left angle of exhaust vent，as control variables. Taking the S1200 roadway in the Caragana mine as the research object，the paper combined the theory of gas-solid two-phase flow and used the Fluent software to establish a finite element model of the dust field with the integrated regulation of airflow at the air outlet and exhaust outlet of the hybrid ventilation. By simulating and analyzing the influence of single parameter control on dust distribution，the reasonable control range of each control parameter under mixed ventilation was determined. Based on the Box-Behnken，the research designed a response surface test for the dust field optimization，and then in terms of the driver’s position and the dust concentra⁃ tion in the pedestrian breathing zone on the return air side，an optimization model was established as the response in⁃ dex. Through the response surface analysis，the significant sequence of the influence of the four control variables on the dust concentration and the optimal airflow control plan for dust field optimization was determined. A 1 ∶ 5 simi⁃ lar experimental test system of the air outlet and exhaust airflow control was built to simulate the S1200 comprehen⁃ sive heading face. Using the test system，the best airflow control scheme was tested and verified，and the dust reduction effect analysis was carried out. The results indicate that when the air outlet is 5 m and 10 m away from the front，the dust concentration at the driver ’ s position was reduced by 46. 1% and 70. 2%， consistently， the average dust concentration in the pedestrian breathing zone on the return side was reduced by 53.8% and 60.5%. The error between the measured value obtained by the experimental test and the predicted value from the optimization mod⁃ el is within 6%，so it verifies the accuracy of the optimal air flow control scheme for the optimization of the dust field.