Flow imbalance and Reynolds number impact on mixing in Confined Impinging Jets

On the 2D nature of flow dynamics in opposed jets mixers

“…Malguarnera and Suh studied the effect of the Reynolds number and the momentum ratio of the opposed jets on the flow, and they proposed that two conditions to obtain a better mixing of the two monomers (isocyanate and polyol) are: the Reynolds number should be larger than and the momentum of the opposed jets should be equal. Other authors have reached similar conclusions on the effect of the Reynolds and the jets’ momentum ratio effect on the flow . The abrupt increase of mixing quality is due to a flow regime transition, which is mainly based on the jets Reynolds number, and the jets impose a strong dimensionality to the flow in CIJs, making the strongest flow dynamics to occur mainly in the plane defined by the mixing chamber axis and the jets axis.…”

“…Downstream of the impingement point, vortices engulf this pancake like structure causing oscillations of the flow in the jets impingement point. These vortices form laminas of fluid from the opposed jets that are oriented in the perpendicular direction to the main flow direction toward the outlet as can be seen in Figure . The thickness of the laminas is around .…”

“…Other authors have reached similar conclusions on the effect of the Reynolds and the jets' momentum ratio effect on the flow. 27,[31][32][33][34][35][36][37][38][39][40][41][42][43] The abrupt increase of mixing quality is due to a flow regime transition, which is mainly based on the jets Reynolds number, and the jets impose a strong dimensionality to the flow in CIJs, making the strongest flow dynamics to occur mainly in the plane defined by the mixing chamber axis and the jets axis.…”

Experimental study of mixing enhancement of viscous liquids in confined impinging jets reactor at low jet Reynolds numbers

“…As the viscosity of fluid in micro/mini CIJR applied in the practical industry is large commonly (20~1000 mPa·s) (Macosko, 1989), the jet Reynolds number is low. The previous studies show that for low jet Reynolds number, the flow in CIJR displays a stable separated regime with poor mixing quality (Tucker and Suh, 1980;Unger et al, 1999;Santos et al, 2008;Fonte et al, 2015). As a result, how to improve the mixing in CIJR under low jet Reynolds numbers is the key issue.…”

“…Santos et al (2008) used the particle image velocimetry (PIV) technique to characterize the flow field in RIM, and results indicate that the mixing in RIM occurs for Re>120. Fonte et al (2015) studied the flow regimes and mixing performance in a confined impinging jets (CIJ) mixer with PLIF at 50<Re<600, and have found that the mixing scales in the flow become smaller and the mixing quality increases with the increase of Reynolds number. As the viscosity of fluid in micro/mini CIJR applied in the practical industry is large commonly (20~1000 mPa·s) (Macosko, 1989), the jet Reynolds number is low.…”