Swirling addition to the stream is beneficial for the fluid mixing. This work aims to study the mixing process intensification in a conventional T-jets mixer by the swirling addition. After experimental verification by the planar laser-induced fluorescence technique

large eddy simulation with the dynamic kinetic energy sub-grid stress model is used to predict how the swirling strength (in terms of swirling number

S

w

) and swirling directions affect the mixing performance

e.g

. the tracer concentration distribution

mixing time

and turbulent characteristics in the T-jets mixers. Predictions show that the swirling strength is the key factor affecting the mixing efficiency of the process. The overall mixing time

τ

90

can be significantly reduced by increasing

S

w

. Vortex analysis shows that more turbulent eddies appear in the collision zone and the turbulent kinetic energy dissipation rate increases obviously with the swirling addition. When

S

w

is kept constant

the mixing process can be accelerated and intensified by adding swirling to only one stream

to both streams with the opposite swirling directions

or to both streams

with the same swirling directions. Amplification of the mixing process by enlarging the mixer size or increasing the flow rates is also optimized. Thus

this work provides a new strategy to improve the mixing performance of the traditional T-jets mixers by the swirling addition.