(312g) Experimental Study of Turbulent Reactive Mixing in a Confined Rectangular Jet Reactor

A detailed understanding of the turbulent reactive mixing is crucial to the design and optimization of chemical reactors. While turbulent shear flows have been studied extensively through the years, the coupling between the mixing process and chemical reaction is far from being clearly understood. This limitation is due to a the lack of suitable experimental data. To address this shortcoming, The use of reactive planar laser-induced fluorescence (PLIF) combined with particle image velocimetry (PIV) can be a powerful technique for obtaining the simultaneous information of chemical reaction and velocity field for these reactive-diffusive flows. Using a combined reactive PLIV/PIV technique, experiments are being carried out in a liquid-phase confined rectangular jet reactor. A simple diffusion-limited acid-base reaction is employed in the reactive PLIF. A turbulent jet flow case with a 1:2:1 velocity ratio of three streams (acid/base/acid) is being investigated at a Reynolds number based on channel hydraulic diameter of 20,000. Disodium fluorescein, a dye whose fluorescence is strongly pH-sensitive, is uniformly premixed with both the acid and base solution. The fluorescence transition is made very sharp by carefully adjusting the concentration of acid and base solution. Hence, the acid/base region and reaction interface can be visualized and determined precisely down to a very small scale. The fluid flow is illuminated by a double pulsed Nd:YAG laser, and two 12-bit CCD cameras with a spatial resolution of 1024 x 1280 px2 are used, which capture PIV and reactive PLIF images simultaneously at the framing frequency of 1 Hz. The experimental findings are employed to validate the performance of computational fluid dynamics (CFD) models for chemical reactions in turbulent liquid flow.