Experimental flow visualizations and velocity measurements are used jointly with numerical simulations to investigate the mixing and monitor the reaction progress in the periodic flow regimes occurring in a T-shaped microreactor. We considered the effects of different kinetic constants, with very different characteristic chemical time scales resulting in a wide range of Damköhler numbers.

A remarkable agreement between experiments and simulations is found both in terms of flow pattern and reaction progress. Two different flow regimes are present for increasing Reynolds number. The first is the periodic asymmetric regime, characterized by the shedding of vorticity-blobs along the mixing channel leading to a further increase of the mixing performance compared to the steady engulfment regime. The second regime is the periodic asymmetric one, which is mainly a poorly mixed segregated regime with periodic oscillation at the interface between the two reactants. The mixing degree significantly increases in the unsteady asymmetric regime, whereas it predictably drops down in the unsteady symmetric regime. In the periodic asymmetric regime the reaction yield follows the same function of the Damköhler number, describing the residence to chemical time-scale ratio, and of a non-dimensional kinetic constant, taking into account also fluid properties, previously proposed for the steady vortex and engulfment regimes. In the periodic symmetric regime, the reaction yield is found to depend only on the Damköhler number, with the same dependence previously highlighted for the steady segregated regime.

实验流动可视化和速度测量与数值模拟结合使用，以研究混合并监测在 T 形微反应器中发生的周期性流动状态中的反应进程。我们考虑了不同动力学常数的影响，具有非常不同的特征化学时间尺度，导致范围广泛的 Damköhler 数。

在流动模式和反应进程方面都发现了实验和模拟之间的显着一致性。存在两种不同的流动状态以增加雷诺数。第一个是周期性不对称状态，其特征是涡流团沿混合通道脱落，与稳定吞没状态相比，混合性能进一步提高。第二种方案是周期性不对称方案，主要是混合不良的分离方案，在两种反应物之间的界面处具有周期性振荡。混合度在不稳定不对称状态下显着增加，而在不稳定对称状态下它可以预见地下降。在周期性不对称方案中，反应产率遵循 Damköhler 数的相同函数，描述了驻留与化学时间尺度比，以及无量纲动力学常数，还考虑了流体特性，之前提出的稳定涡旋和吞没状态。在周期性对称状态下，发现反应产率仅取决于 Damköhler 数，与之前强调的稳定分离状态相同的依赖性。