Effect of the opening of a butterfly valve on the dynamic evolution of cavitation

As the key control equipment for the transmission of fluid medium, processing valves are widely used in the transmission systems of fluid medium in energy, chemical industry, metallurgy and other fields, which play important roles in the stability and reliability of the system operation. When the flow cross-section is operated in a sudden change, the pressure decreases rapidly at the downstream, which leads to the cavitation in the processing valves. Cavitation makes serious erosion and damage on the valve core and pipeline surface, which makes the leakage and noise problems in processing valves. This seriously affects the regulation performance and lifetime of processing valves. In this article, numerical simulations were carried out to investigate the transient cavitation in a model butterfly valve. By considering effects of local pressure on formation of cavitation, a modified model for calculating the diameter of cavitation bubbles was derived. Effects of valve opening degree were investigated on the dynamic evolution of cavitation by analyzing formation, development and collapse of cavitation. The generation, development and collapse of single cavitation bubble was obtained and discussed in details to state the interaction between vortices and cavitation. Attached and quasi-periodic cavitation were observed and analyzed at different valve opening degrees in detail as well.