Journal of Xi'an Jiaotong University

Large Eddy Simulation of Mixing Effect in the Tubular Static Mixer with Different Tab Structures
Zhang Hongyan¹,Chen Xiaochun¹,Wang Yuan²
(1.School of Environmental and Municipal Engineering,Xi'an University of Architecture and Technology, Xi'an 710055,China;2.The Center for Environment and Modern Agriculture Engineering,Xi'an Jiaotong University,Xi'an 710049,China)

Abstract:Flow structure and concentration fields in the tubular static mixer with rows of tabs were investigated by means of large eddy simulation (LES).Flow mixing effect and static pressure distribution along the axis of the tubular static mixer with big tabs,small tabs, and long tabs were compared. The numerical results show that the mixer with small tabs exhibits the lowest resistance(ξ_s=0.52) but the mixing effect is the worst. However,the mixer with long tabs has a better mixing effect and also a lower resistance down to 67% of that with big tabs(ξ_l=2.31;ξ_b=3.41).For the tubular static mixer with long tabs,two anticlockwise vortices are formed behind the tabs,resulting in larger velocity gradient,significant shear stress, and intensified turbulent intensity in the center of mixer. This flow structure induced by long tabs can efficiently drive the high concentration flow to move from center to the region near the wall of the mixer and thus greatly increase the contact area between the high concentration flow and the low concentration flow.It can be concluded that long tabs are good candidates to improve mixing effect in the tubular static mixer.
Keywords:tubular static mixer;tabs;mixing effect;large eddy simulation