Numerical Simulation Of Flow And Mixing Characteristics In The Venturi Mixer

The venturi mixer is one of static mixing device that efficiently and quickly mixes many strands of fluid in proportion and delivers them.The current researches about effect of structural parameters and operating conditions on flow and mixing characteristics in the venturi mixer are not comprehensive and in-depth enough,which result in lacking of support of data and theory in the design and operation of the venturi mixer.Therefore,effect of structural parameters and operating conditions on flow and mixing characteristics in the venturi mixer were investigated in this work.In this work,simulations were verified by experiments,which confirmed accuracy and applicability of numerical simulation method.Effects of contraction ratio,throat length-diameter ratio,convergent angle,divergent angle,orifice-throat ratio,angle of ejection segment,position ratio of ejection segment,number of ejection segment, and velocity ratio on velocity distribution,pressure distribution,concentration distribution,throat pressure,pressure lose coefficient,vacuum conversion coefficient,pressure difference of inlet and outlet,ejection ratio and mixing strength were explored.The optimal structural parameters and operating conditions of the venturi mixer were obtained.In this work,it is found for structural parameters that,the greatest effect is contraction ratio and the smallest is throat length-diameter ratio on flow characteristics of the venturi,the greatest effect is orifice-throat ratio and number of ejection segment and the smallest is position ratio of ejection segment on flow and mixing characteristics of the venturi mixer.Among structural parameters of the study,the optimal structural parameters are contraction ratio of 0.71,throat length-diameter ratio of 0.8,convergent angle of 28 °,divergent angle of 8 °,orifice-throat ratio of 0.3,angle of ejection segment of 150 °,position ratio of ejection segment of 0.1,number of ejection segment of 4.The performance of the optimized venturi mixer is improved,including a 61.6 % reduction in pressure loss coefficient,a44.1 % increase in vacuum conversion coefficient,an 85.6 % reduction energy consumption per unit ejection ratio in ejection ratio and a 4.8 %increase in mixing intensity.For operating conditions,in the venturi,increasing is beneficial to its performance,in the passive venturi mixer,increasing reduces its performance,and in the active venturi mixer,increasing velocity ratio is conductive to the improvement of performance.The active operating condition is superior to the passive operating condition in the term of mixing.In this work,the flow and mixing characteristics in the venturi mixer were further understood,which provided reference and help for the design and operation of the venturi mixer.