Multiparametric experimental analysis of the pin disc rotational cavitation generator

Abstract

The alarming increase in water pollution is driving research into novel, environmentally friendly treatment solutions such as hydrodynamic cavitation. This study is part of the research on the pin disc rotational generator of hydrodynamic cavitation, which utilises the low pressure wake behind the rotor pins to induce cavitation and the short gap between the rotor and stator pins to enhance cavitation cloud fluctuation. Due to the lack of understanding of the effects of cavitation treatment, a laboratory device was built to investigate the mechanisms of cavitation generation and the effects of various geometric features such as the diameter, number, and shape of the rotor pins and the gap size between the rotor and stator pins. Using simultaneously measured pressure fluctuations and high-speed visualisation, a method was developed to quantify the extent of cavitation, and it was found that throttling the high-pressure side had an order- of- magnitude smaller effect on cavitation than the number of rotor pins. It was found that a smaller number of rotor pins with large downstream area produced the most aggressive cavitation conditions. The weak spectral response and lower mean vapour cloud area, as well as the lower fluctuation in the case without stator, demonstrated the key role of the stator in the onset and aggressiveness of cavitation.

Keywords

• Hydrodynamic cavitation pinned disc reactor
• Cavitation dynamics
• Flow visualization
• Multiparametric analysis