The Influence of Turbulence on Mass Transfer From Cylinders

Abstract

This paper describes new local mass-transfer measurements from two cylinders, coated with a layer of paradichlorobenzene (p-C6H4Cl2), to air. The cylinders were placed in cross flow, and measurements were performed at three nominal values of the Reynolds number (75, 100, 125 × 103) as well as at varying levels of turbulence intensity. In the range where the boundary layer is laminar, the effect of turbulence intensity is always to increase the transfer rate, approximately by a constant factor φ which depends on the turbulence intensity as well as the Reynolds number. Across the turbulent boundary layer and wake the influence is not systematic, as both increases and decreases are observed. The data for the stagnation line are compared with other measurements. They can all be correlated against the single parameter TuRe1/2, as suggested by a semiempirical theory due to Smith and Kuethe. However, the global correlation equation (a second-degree polynomial) differs from the originally proposed linear relationship, and the uncertainty is one of ±8 percent.