Study On Cavitation Characteristics Of Irregularities Offset Away From Flow And Optimization Study Of Hydrodynamic Cavitation Reactor

This thesis has included two main parts: (1) Experimental study on testing flow field of offset away from flow with PIV (2) Study on optimum design of hydrodynamic cavitation equipment by using Flow-3D numerical simulation software.The first part is to reduce cavitation erosion as a starting point. The aerated behaviours in cavitation region of high velocity flow through the non-circulating water tunnel are investigated by using the advanced experimental facilities in the hydraulics laboratory at Zhejiang University of Technology. By measuring the change of velocity in the cavitaition region, the 2D-structure of the cavitation region and the extent of cavitation are investigated through comparing two different specimens(abrupt and sloping offset away from flows) with different aeration rates, and flow characteristics are also analyzed. Experimental results show that offsets away from flows are characterized by smaller cavitation cloud, lower-resolution, lower intensity, less obvious cavitation phenomenon, and aeration can efficiently reduce the cavitation which is induced by offset away from flow. As the same height , the cavitation phenomenon casued by sloping offset away from flows much slighter than abrupt offset away from flows. Therefore, in actual projects, as the irregularities on overflow surface in spillway tunnel is inevitable, in order to prevent the erosion due to the irregularities, an effective measure is to substitute any other kinds of irregularities for sloping offset away from flows.The second part is to use the cavitation phenomenon as a starting point. Based on hydraulic principles, an experimental setup of hydrodynamic cavitation has been established and different kinds of hydrodynamic cavitation elements have been presented. In order to find best element which can enhance the cavitation phenomenon, the cavititon region has been analysed by using Flow-3D numerical simulation software. the theoretical and experimental results are compared to further verify the findings. This study not only has the important theoretical significance in explore the mechanism of cavitation, but also of certain guidance significance to the optimal design of hydrodynamic cavitation elements and further experiment. hydrodynamic cavitation elements can be used as a new technology in wastewater treatment.