(712g) PIV Experimental Characterization of Fluid Dynamics Generated By a Rotating Inner Cylinder with Rough Surface in Taylor–Couette Reactors

The flow dynamics in Taylor-Couette reactor (radius ratio η=0.8, aspect ratio of 10) was experimentally characterized using a two-dimensional particle image velocimetry for a range of Reynolds numbers Re from 2000 to 20000, corresponding to turbulent vortex flow regime. The effect of the roughness of the surface of inner rotating cylinder on the velocity field and turbulent quantities in the Taylor-Couette reactor has been investigated. The roughness of inner cylinder wall is achieved by using a square hole perforated wire mesh firmly wrapped on the inner cylinder with a mesh number of 20 and a wire diameter of 1mm. The velocity field, the Reynolds stress, the turbulent kinetic energy and the turbulent dissipation rate were obtained from the PIV data. The experimental results acquired in the TC reactors adopting a rotating inner cylinder with rough surface were compared with that in a TC reactor using a same size rotating inner cylinder with smooth surface. It is found the Tylor – vortex was obviously deformed by using the inner cylinder with a rough surface when the Reynolds number exceeding 6000. The highest turbulent kinetic energy was found to occur at the position of outflow boundary of Taylor vortices for both TC reactors using inner cylinder with rough surface and inner cylinder with smooth surface. However, the overall turbulent kinetic energy of flow field generated by rough surface inner cylinder is significantly increased by almost 300% in comparison with that produced by smooth inner cylinder when Reynolds number is 6000. In terms of turbulent energy dissipation, only a part of total turbulent energy dissipation was resolved due to the limits of resolution of PIV method, so the direct evaluation and sub-grid-scale method were used to estimate the remaining unresolved turbulent dissipation rate. The results show that the maximum turbulent dissipation rate is also observed at the outflow boundaries of Tylor vortices, the overall turbulent dissipation rate of the fluid field generated by the smooth surface inner cylinder is greatly smaller than that of inner cylinder with rough surface.