Tracer gas measurement and simulation of turbulent diffusion in mine ventilation airways

The effective diffusion coefficients in mine ventilation-flows had been obtained as 4 to 200 m²/s by matching the measured concentration-time curves with the advection-diffusion equation. The turbulent diffusion coefficients in the simple airways have good agreement with the equation proposed by Taylor. However, for complex airways in operating mines, the evaluated effective diffusion coefficients in the mines show higher values than that calculated by the Taylor's equation. A numerical simulation model using with movements of discrete particles dosed into ventilation flows has been developed to simulate diffusion phenomena of gas or dust in mine airways. Numerical simulations had been conducted on distribution of tracers in single airways with ordinary profiles of mean velocity, velocity fluctuations and Reynolds stress. As one of results, long band of diffused particles is obtained at the single airway of 600 m in length, and large effective diffusion coefficient is evaluated as 20 m²/s.