“…As growing number of butterfly valves are required in various application fields, valves of higher quality are also demanded for. In order to improve the performances of butterfly valves, increasing studies have been carried out, focusing on several hot topics, including the flow characteristics [1][2][3][4][5][6][7], contact pressure distribution [8], cavitation phenomenon [9][10][11], pressure loss [1,2,5,7,12,13], as well as drive characteristics [6,14,15]. All these studies have brought insights for the design of butterfly valves and contributed to the development of butterfly valve industry.…”