Instabilized Fluid Flow at Interface of Chemical Reaction in Liquid Phase

Abstract

Evolution of chemically reacting flow has been studied experimentally using Hele-Shaw Cell.Neutralizaftion reaction of HCl+NaOH with different pH indicators is adapted for the chemical reaction. Low density liquid (HCl) and high density liquid (NaOH with different pH indicator) pour into upper layer in the cell and lower layer in the cell, respectively. In HCl+NaOH with 10% Bromothymol Blue (BTB) system, although some small proturbulences form and disappear repeatedly at a reaction front, flow patterns are stable and the front moves almost parallel to a horizontal line with time elapses. The higher initial concentration of reactants hastens the chemical reaction. On the other hand, in HCl+NaOH with 10% phenolphthalein (PP) system, unstable flow patterns are visualized, the chemical reaction is higher than that in the HCl+NaOH with BTB system. By the chemical reaction, temperature increases locally in the cell and density of product is smaller than that of HCl. It seems that the local temperature difference and density difference bring on the unstable flow patterns.