Research on the Mixing Uniformity of Coal Mine Methane Swirl Mixer Under Given Inlet Condition

The mixing uniformity of coal mine methane swirl mixer was numerically investigated under given inlet condition focusing upon the effects of swirl way and swirl intensity on the outlet uniformity of velocity and concentration distributions. The results show that, on condition that the flow mass and moment of inertia of outer tube gas are greater than that of inner tube, the swirl flow of outer tube gas dominates the velocity field at outlet and decrease the outlet velocity distribution uniformity. The swirl flow of inner tube gas sets up the reverse pressure gradient in radial and axial direction that leads to the creation of return flow region, which enhances the momentum and mass exchange of inner and outer tube gases and significantly improve outlet concentration distribution uniformity. With the increase of swirl intensity, the outlet velocity distribution uniformity decreases for swirl ways with outer tube gas swirling, while the mixing intensity strengthens in return flow region which contributes to the improvement of concentration uniformity for swirl ways with inner tube gas swirling.