Mixing characteristics of HEV static mixer with different tab gaps and tab wing(the distance between the last tab and the outlet)were studied experimentally and numerically.The most widely used measure for the uniformity is the coefficient of variation(CV).Smaller CV value means more uniform mixture.The volume fraction of tracer fluid was measured at the outlet

and the results were compared with standard k-ε equation

RNG k-ε equation

realizable k-ε equation

SST k-ω equation and standard k-ω equation

based on which the most suitable equation was obtained.Using this model

the CV of tracer fluid with different tab wing was studied when the tab gap was from 0.8D to 2.0D

where D is the inner dimeter of HEV static mixer. The CV of the tracer fluid at different spacing at the same benchmark section was also studied.The results showed that RNG k-ε turbulent model was in a good agreement with the experimental results with the relative error of 3.37%.It was also found that the CV decreased rapidly as the tab gap increased when tab gap≤1.7D and increased as the tab gap increased when tab gap≥1.7D.The optimum tab gap is 1.7D.The attenuation of CV was fast as tab wing increased in a certain distance

and then became comparatively slow.