Aerodynamic scale model for simulations of methane control at the return end of longwall retreat coal faces

The control of methane gas in coal mines can be aided by predictions of the consequences of various changes in mining conditions or systems. In principle, such predictions can be made by computer simulations; however, in practice the solution of the equations for the flows and gas dispersion rely on various approximations and numerical solutions. therefore, there is a role for physical small scale model simulations with the flow characteristics scaled so that the model performs aerodynamically just like the full scale system. The flow properties which have to be preserved include the turbulent dispersion on the face, the formation of layers due to gas density, the division of the ventilation flow between the main flow through the face and seepage flow through the waste, and dispersion of gas in the waste. Specifications are identified which ensure that the flows in the small scale model are similar to those in the full scale. A physical scale model which meets these specifications is described. Results are presented from simulations of various locations of the sources of gas emission in the waste and the consequent effects on gas concentrations near the return end of a retreat coal face. 49 refs., 6 figs., More>>