Numerical investigation on the hydrodynamic performance with special emphasis on the cavitation intensity detection in a Venturi cavitator

Abstract

Venturi is one of the structures that have been frequently adopted for the generation of hydrodynamic cavitation, which is now a promising technology and method in wastewater treatment. Despite the wide spread application, insight into the characteristics of cavity dynamics and cavitation intensity to optimize cavitation performance remains lacking. This paper presents computational investigation of the cavitation performance with emphasis on cavitation intensity prediction inside a Venturi cavitator, through a robust modeling approach. Particularly, a new physical model as the criterion to account for the evaluation of cavitation intensity was developed. The predictions gave satisfactory agreement with published data for acoustic bubble dynamics, and experimental results for typical cavitation characteristics of the Venturi. Further investigations analyzed the size oscillations, collapse pressure and collapse temperature of bubbles, as well as the cavitation intensity during its dynamic behavior of the hydrodynamic cavitation in this cavitator. The results showed that the bubbles originally generated near the wall of the Venturi had the strongest oscillations for cavity dynamics. The normalized average bubble collapse pressure was consistent with the distributions of the cavitation intensity within the whole flow domain. Besides, the rear part of the attached cavity at the stage of developing cavitation showed the strongest intensity of cavitation, while the chocking cavitation had no advantage for this issue. This research provides an available and useful criterion to effectively compare and evaluate the bubble dynamics and cavitation intensity in the multiphase flow of cavitational reactors.