The turbulent behavior of novel free triple-impinging jets with large jet spacing by means of particle image velocimetry

doi:10.1016/j.cjche.2016.04.022

Abstract

Abstract: A novel reactor that achieves rapid liquid-liquid mixing via free triple-impinging jets (FTIJs) is developed to improve mixing efficiency at unequal flow rates for liquid-liquid reactions. The flow characteristics of FTIJs were investigated using particle image velocimetry (PIV). The instantaneous and mean velocities data at different Reynolds numbers (Re) were analyzed to provide insights into the velocity distributions in FTIJs. The effect of jet spacing on the stagnation points, instantaneous velocity, mean velocity, profiles of the x- and y-components of mean velocity, and turbulent kinetic energy (TKE) distributions of FTIJs were investigated at Re=4100 with a volumetric flow rate ratio of 0.5. The characteristics of the turbulent flows are similar for all jet spacings tested. Two stagnation points are observed,which are independent of jet spacing and are not located in the center of the flow field. However, velocity and TKE distributions are strongly dependent on the jet spacing. Decreasing jet spacing increases the expansion angle and the values of TKE, leading to strong turbulence, improving momentum transfer and mixing efficiency in FTIJs. The present study shows that optimization of the operating parameters is helpful for designing FTIJs.

Key words: Expansion angle, Free triple-impinging jets, Turbulent kinetic energy, PIV

摘要： A novel reactor that achieves rapid liquid-liquid mixing via free triple-impinging jets (FTIJs) is developed to improve mixing efficiency at unequal flow rates for liquid-liquid reactions. The flow characteristics of FTIJs were investigated using particle image velocimetry (PIV). The instantaneous and mean velocities data at different Reynolds numbers (Re) were analyzed to provide insights into the velocity distributions in FTIJs. The effect of jet spacing on the stagnation points, instantaneous velocity, mean velocity, profiles of the x- and y-components of mean velocity, and turbulent kinetic energy (TKE) distributions of FTIJs were investigated at Re=4100 with a volumetric flow rate ratio of 0.5. The characteristics of the turbulent flows are similar for all jet spacings tested. Two stagnation points are observed,which are independent of jet spacing and are not located in the center of the flow field. However, velocity and TKE distributions are strongly dependent on the jet spacing. Decreasing jet spacing increases the expansion angle and the values of TKE, leading to strong turbulence, improving momentum transfer and mixing efficiency in FTIJs. The present study shows that optimization of the operating parameters is helpful for designing FTIJs.

关键词: Expansion angle, Free triple-impinging jets, Turbulent kinetic energy, PIV

Jun Zhang, Youzhi Liu, Ying Luo. The turbulent behavior of novel free triple-impinging jets with large jet spacing by means of particle image velocimetry[J]. Chin.J.Chem.Eng., 2016, 24(6): 757-766.

Jun Zhang, Youzhi Liu, Ying Luo. The turbulent behavior of novel free triple-impinging jets with large jet spacing by means of particle image velocimetry[J]. Chinese Journal of Chemical Engineering, 2016, 24(6): 757-766.

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