Stereoscopic PIV Visualization of Flow Characteristics on a Flapping-type Tidal Turbine

Abstract

The flapping type turbine is typically operated with a swing motion activated by a given pitch motion of the hydrofoils. The power is then extracted by the oscillatory swing motion. Thus, it is important to know an interrelationship among the key parameters of the oscillation such as a frequency, a swing-amplitude, a pitch angle, a load imposed for the power extraction and so on. Therefore, this study is focused on the analysis of flow characteristics of the flapping-type turbine with its oscillated movement. Flow fields around the flapping type turbine are explored by a visualization technique based on stereoscopic particle image velocimetry (SPIV) measurement over the oscillating zone of the hydrofoils. It is found throughout the experiment studies that the oscillating frequency, the pitch angle, and the imposed load are key factors in affecting on the power extraction as well as its controllability. Eventually, the flow analysis by the PIV visualization will be utilized for obtaining the optimal design of a large scale flapping-type tidal turbine.he key parameters of the oscillation such as a frequency, a swing-amplitude, a pitch angle, a load imposed for the power extraction and so on. Therefore, this study is focused on the analysis of flow characteristics of the flapping-type turbine with its oscillated movement. Flow fields around the flapping type turbine are explored by a visualization technique based on stereoscopic particle image velocimetry (SPIV) measurement over the oscillating zone of the hydrofoils. It is found throughout the experiment studies that the oscillating frequency, the pitch angle, and the imposed load are key factors in affecting on the power extraction as well as its controllability. Eventually, the flow analysis by the PIV visualization will be utilized for obtaining the optimal design of a large scale flapping-type tidal turbine.