Investigations of gas-flow patterns within a cylindrical glass tube having dimensions identical with those of a graphite furnace atomizer under the influence of forced convective flow

Abstract

Gas-flow patterns within a cylindrical glass tube having the same dimensions as a typical graphite furnace atomizer were investigated by introducing two streams of argon gas seeded with a light-scattering medium of TiO₂ particles into the open ends of the tube and viewing the scattering profiles of the particles. By placing a sample of iodine solution near the centre or ends of the cylindrical glass tube, further insight into gas-flow patterns is gained by examining the spatial distributions of the iodine vapour under the influence of convective flow. The TiO₂ particle and iodine spatial profiles suggest that at room temperature the argon streams follow a laminar-flow pattern in the bulk-flow region between the ends of the cylindrical tube and the sample introduction hole; however, at the junction region where the two argon streams converge and discharge from the dosing hole, local turbulences or eddies may be generated owing to abrupt changes in gas-flow velocity and direction in the vicinity of an area (boundary layer) directly beneath the dosing hole.