Flow visualization of Butterfly valve is tested five cases(15°, 30°, 45°, 60° and 90°) of vlave opening angle. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics of butterfly valve about discharge of dam.. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated each cases. The results from flow visualization using PIV through the video which do not contain a cavitation phenomenon was confirmed in accordance with the valve opening. Performs valve opening and the flow properties of the Karman vortex generated by the frequency analysis is 90° was calculated the frequency of the butterfly valve applied to the actual dam. Butterfly valve for the emergency discharge valve is susceptible to cavitation caused by the valve opening 90° and repeat the cycle in the valve side of the vortex emission system is a high possibility of damage due to fatigue.

• 김동균(Member, an assosiate professor in the department of Mechanical engineering of Tongmyong university) | Dong-Kyun Kim Corresponding Author