912 Evaluation of Mass Transfer Coefficient Behind an Orifice with Allowable Orifice Bias in a Pipe Flow : Effect of Swirling Flow

In the present paper, the mass transfer phenomenon behind an orifice in a pipe flow is studied by measuring the mass transfer coefficient along the pipe wall using naphthalene sublimation method. An attention is placed on the asymmetrical pipe-wall thinning behind an orifice under the influence of swirling-flow intensity and allowable orifice bias. The present measurement indicates that the mass transfer coefficient becomes asymmetric about the pipe axis by the combined effect of swirling flow and allowable orifice bias. It is found that the enhancement of mass transfer coefficient is observed on the shorter side of the orifice plate and the reduction is found on the opposite side. This phenomenon is found to be consistent with the flow-field observation in the previous study.