Study on Turbulence Structure of Surface-Renewal Motion by using a Laser-Fluorescence and modelling of Gas-Absorption Mechanism

点击翻译按钮获取中文摘要

Mass transfer into a turbulent liquid across the gas-liquid interface in the absence of external interfacial shear was experimentally investigated in both open-channel water-flows with and without grid-generated turbulence. The frequency of the appearance of surface-renewal eddies and the scales of surface-renewal eddies were measured by conditionally processing the concentration signal of the tracer emitted from a point source; the mass-transfer coefficient on the liquid side was estimated through carbon-dioxide absorption experiments. The mass-transfer coefficient was significantly correlated with the frequency of the appearance of large-scale renewal eddies in both open-channel flows with and without turbulence grids. The results show that the large-scale eddies control the mass transfer across the gas-liquid interface into turbulent liquid flows in the absence of an external interfacial shear. Based on the results, mass transfer mechanism was modelled by using the surface-renewal concept.