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Dynamics of direction-specific friction probes for the electrodiffusion diagnostics of flow in rheologically complex liquids

  • Identification: GA104/04/0826 - Grant Agency of the Czech Republic
  • Duration: 2004 - 2006
  • Principal investigator: Prof. Ing. Ondřej Wein DrSc. (Institute of Chemical Process
    Fundamentals ASCR)
  • Co-investigator: Doc. RNDr. Petr Štern CSc.

Subject of research

Electrodiffusion (ED) sensors work on the polarographic principle. Depending on the operation mode, they detect either concentration/diffusivity of the depolarizer (oxygen, quinon, triiodide, ferricyanide) or a local kinematics of surrounding liquid. Depending on actual construction, they monitor local velocity (anemometers) or velocity gradient (friction probes). Multi-segment ED friction probes, in addition, monitor also the varying flow direction. Unfortunately, their safe use is still limited to slowly varying flows and to homogeneous liquids. In the suggested project, we intend to improve their function by using our knowledge of the single-segment probe dynamics. The computer-aided calibration and control of multi-segment ED probes would be improved by (i) including the effect of insulating gaps on dynamics (essential in fast changing flows), (ii) including the effect of longitudinal diffusion (essential in slow flows, low Peclet numbers), (iii) including the dynamic (voltage-step)

 

Research Goal

An automated experimental set-up was built for testing of direction-specific (multi-segment) electrodiffusion (ED) probes under dynamic conditions (time-dependent harmonically superposed shear flow, potentiostatic transient process). The software package