Experimental and numerical assessment of impingement and mixing of urea-water sprays for nitric oxide reduction in diesel exhaust

The findings suggest that at low cross-flow conditions two counter-rotating kidney vortices are formed which entrain reflected droplets of the spray impinging on the channel floor, which leads to improved mixing. Vapor concentrations increase close to the side walls and reflected droplets lead to film-formation on the side walls. At higher cross-flow velocities, vortex formation is not evident and spray-wall interaction is less pronounced - impairing mixing and leading to a reduction in concentration uniformity at down-stream locations. Film formation and high vapor concentrations are restricted to the bottom channel centerline.