Research on the dynamic evolution law of gas and quadratic programming of air volume under the Y-shaped ventilation with three inlets and one return

In order to investigate the dynamic evolution of the gas field in the working face and goaf under the Y-shaped ventilation system with three inlets and one return and to explore the optimal air quantity distribution in the intake airway, a porous medium model is established for the 31002 working face in a coal mine in Shanxi province.The numerical simulation of the gas flow field in the working face and goaf is implemented using Ansys Fluent.The study analyzes the basic distribution patterns of gas concentration, air pressure, and air flow in the gas flow field of Y-shaped ventilation system with three inlets and one return, as well as the evolution of gaseous species concentration under different air quantity ratios in the three intake airways.Thirty sets of sample data are generated through simulation, and a multivariate nonlinear regression function for air volume and upper corner gas concentration is fitted.Based on the prior rules obtained from numerical simulation, a quadratic programming solution is applied to the objective function, ultimately determining the optimal air volume ratio.The research reveals that near the working face area, vortex flow occurs when the airways 2 and 3 are close, leading to gas accumulation to some extent.When the air quantity in intake airway 1 exceeds the sum of the that in the other two airways, the gas accumulation area in the working face ranges from 90 m to the upper corner, and the gas concentration accumulation area in the goaf near the working face is from 90 m to 220 m. Changing the air quantity ratio between airways 2 and 3 results in an average decrease in gas concentration of approximately 0.19%.Under the constraints of the prior rules obtained from numerical simulation, the optimal air volume ratio for the three intake airways is determined to be 1.08∶1.23∶1.23.This study provides theoretical support for the control of gas over limit in the working face and the prevention of gas disasters in coal mines.