Abstract
A pipe-wall thinning phenomenon behind an orifice in a circular pipe is studied by measuring the mass transfer using the naphthalene sublimation method. An attention is placed on an asymmetric increase of local mass transfer behind the orifice, which is combined with the influence of swirling flow and the orifice bias. The present results indicate that the mass transfer is generally increased with an increase in swirl intensity. However, it becomes asymmetric by the combined effect of the orifice bias for the bias larger than 0.4% of the pipe diameter and the swirl intensity larger than approximately 0.2. The enhanced mass transfer is found on the shorter orifice side behind a biased orifice, and the maximum mass transfer is increased 40% in comparison with the case without swirl and orifice bias.
