The effects of inflow conditions on reactive–diffusive mechanism in a shear mixing layer at low Reynolds number

• Reactive–diffusive mechanism in a shear mixing layer with a fast chemical reaction at low Reynolds number is investigated.
• Promotion effects of trip wires and a grid on mixing and reaction are quantitatively shown.
• This research would contribute to optimization in designing mixers and reactors.

The effects of inflow conditions on the reactive–diffusive mechanism in a liquid shear mixing layer are experimentally investigated. Trip wires and a turbulence-generating grid are installed at the entrance to the test section not only to develop the mixing layer but also to promote scalar mixing and chemical reaction. Instantaneous streamwise and vertical velocities and concentration are simultaneously measured using a combination of a laser-Doppler velocimeter and a laser-induced fluorescence technique. The results show that both the trip wires and the grid increase disturbances at small scales, and scalar mixing and chemical reaction are significantly enhanced. The grid promotes chemical production more effectively than the trip wires under the condition that the mass diffusion is at the same level between the two flows. This is attributed to the fact that the grid enhances both mass diffusion and substitution of the unreacted reactant with the reacted reactant at the fluid interfaces, whereas the chemical product is entrained by the coherent eddies and stays in the interfacial region in the mixing layer with the trip wires.

Graphical AbstractFigure optionsDownload as PowerPoint slide