Visualization and numerical simulation of hydrodynamic cavitation in single hole orifice plate
1. School of Energy and Power Engineering, Jiangsu University, Zhenjiang， Jiangsu 212013, China; 2. Institute for Energy Research, Jiangsu University, Zhenjiang， Jiangsu 212013, China
Abstract：As a simple hydrodynamic device,the single hole orifice plate was used to intensify liquid-liquid heterogeneous macromixing for preparing biodiesel or emulsified diesel.A flow visualization experiment system was set up with transparent hydrodynamic cavitation reactor to investigate the cavitation in the orifice plate and the outlet of the orifice plate.A high resolution and speed CCD equipped with long distance microscope device was used to acquire flow images of different ambient pressures. The effects of back pressure and cavitation number on the change of hydrodynamic cavitation were investigated.The results show that the cavitation inception hysteresis phenomenon is observed for fixed back pressure.When the back pressure reaches certain level, the flowing loss at high back pressure is smaller than that at low back pressure. Some cavity bubbles merge into large-scale bubbles and exist in the downstream region of orifice plate to cause choking flow. The cavitation in orifice plate has great impact on the outlet of orifice plate. Compared the numerical simulation results with the experimental results measured by high speed camera,it is found that LES model can well predict the cloud cavitation and the re-entrant jet which is central to the process of cloud cavitation shedding.With the development and collapse of cloud cavitation,the length of cavity changes periodically.
2017, Vol. 38 
