THE EFFECTS OF DIFFUSER SHAPE OF TIDAL CULLENT GENERATION IN TSUGARU STRAIT ON ACCELERATION EFFECT

Abstract

 In exploring the feasibility of small-scale tide and ocean current power generation with the gradual extended diffuser with flanges in the Tsugaru Strait, the shape of the diffuser specialized for the local flow conditions are optimized through model experiments and numerical simulations. The each dimensions of the flange length (h), the opening angle (θ) and the diffuser length (L) are altered experimentaly. The mechanism of increasing the internal passing velocity of the diffuser are verified by comparing with the each dimension cases. The results of experiments from the variation of h and L show that the traction of the negative pressure region due to the generation of the vortex behind the flange is one of factors of the acceleration mechanism, and the variation of θ show that the lifting force working in the direction of the diffuser's outer edge is also the factor of the acceleration. The analysis shows that the increase of the vortex scale and the turbulence behind the diffuser, respectively in case of h and L changes largely and decrease in pressure reduction effect in case of θ changes largely inhibit the development of the accelerating region.