CIESC Journal ›› 2020, Vol. 71 ›› Issue (10): 4632-4641.doi: 10.11949/0438-1157.20200303

• Fluid dynamics and transport phenomena • Previous Articles     Next Articles

Chaotic mixing performance and mass transfer enhanced by rigid-flexible impeller with pulse jet

Zuohua LIU1,3(),Wei SUN1,3,Xia XIONG1,3,Changyuan TAO1,3,Yundong WANG2,Fangqin CHENG4   

  1. 1.School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
    2.Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
    3.State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
    4.Institute of Resources and Environment Engineering, Shanxi University, Taiyuan 030006, Shanxi, China
  • Received:2020-03-23 Revised:2020-07-10 Online:2020-10-05 Published:2020-08-15
  • Contact: Zuohua LIU


Conventional stirred reactors generally use rigid impeller for mechanical stirring, which leads to the easy creation of isolation mixing regions in the reactor and reduces the efficiency of fluid mixing. The use of multi-flow field coupling to induce chaos and promote more fluids into a chaotic state is one of the effective ways to improve fluid mixing efficiency. In this work, the largest Lyapunov exponent(LLE) and multi-scale entropy(MSE) are investigated with the Matlab compile pressure pulsation signals. The effects of duty ratio, paddle type, flexible paddle thickness, paddle height from the bottom and pulsed air jet flow rate on the chaotic mixing of fluids in a stirred reactor under different pulse periods are explored. In addition, the effects of different impeller types, jet types and air jet flow rate on the volume oxygen mass transfer coefficient KLa are compared and analyzed. When T=0.4 s and D=80%, the results show that the LLE of the rigid-flexible RT impeller compared with the rigid RT impeller increases 11.58% and the MSE of the rigid-flexible RT impeller is also larger than that of rigid RT impeller. It was showed that the pulsed jet rigid-flexible impeller system can better enhance fluid chaos, increase the fluid mixing efficiency and homogenize the system energy distribution. In addition, pulse jet coupling RF-RT impeller system enhances the turbulent characteristics of the fluid, promotes the reduction of the thickness of the liquid film, strengthens the mass transfer and increases the KLa value of the system. When power consumption per unit volume is 360 W/m3, the KLa of the PJ-RF-RT system compared with the PT-R-RT system increases 13.46%, and the KLa of the PJ-R-RT system compared with the SJ-R-RT system increases 11.86%.

Key words: chaos, pulse jet, rigid-flexible impeller, largest Lyapunov exponent, coefficient of mass transfer

CLC Number: 

  • TQ 028.8


Mixing experimental apparatus"


Jet types"


Impellers used in experiment"


Pulse electric signal waveform"


Effect of pulsed duty ratio on LLE"


Effect of impeller types on LLE"


Effect of thickness of flexible part on LLE"


Effect of impeller off-bottom clearances on LLE"


Effect of pulsed air jet flow rates on LLE"


Effect of impeller types on MSE"


Effect of thickness of flexible impeller on MSE"


Effect of pulsed air jet flow rates on MSE"


Effect of impeller types on KLa"


Effect of pulsed air jet flow rates on KLa"

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