CONTROL OF TURBULENT MASS TRANSFER IN BACKWARDFACING STEP FLOW USING ACOUSTIC EXCITATION
Keywords:
Backward-facing step, turbulent control, acoustic excitation, mass transferAbstract
An acoustic excitation serves as a mean of turbulent control of an electrolyte flow in a backward-facing step channel equipped with electrochemical cells to improve convective mass transfer of an electrochemical process. Comprehensive experimental works were done on the effects of fluid dynamical and acoustics excitation parameters on the rate of mass transfer between electrodes. The solution of CuSO4 of 0.5 M (mol/l) was used as the electrolyte fluid. The rate of mass transfer was determined by measuring the local limiting current at mini cathodes placed in the electrochemical cell. Some results showed that the acoustic excitation altered the rate of mass transfer in the flow field. As the Reynolds number increases the influence of acoustics excitation on the enhancement of mass transfer rate becomes less significant and the maximum mass transfer coefficients tend to converge into a single value. Furthermore, there exists an optimum Strouhal number of excitation that will support an optimum rate of mass transfer which may be attributed to the existence of optimum effective forcing frequency to support the production of large scale vertical structure in the shear layer and vortex amalgamation process in a separating-reattached flow.References
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