Flow pattern and coefficient of discharges: hydranlic characteristics in hybrid-type fishway (I)

摘要

The flow pattern and the coefficient of discharges were examined experimentally in the hybrid-type fishway(width B=0.8 m , slope I=1/10) consisted of a recutangular notch(b=0.2 m) at the center wall and a triangular type weir at the either wall (1:7). As regards to the flow pattern, when the value of L/PL(L=horizontal distance until the drop point of nappe, PL=horizontal pool length) becomes more than about 0.3, the central flow formed stream type in the case of PL/B=0.46. Regarding the pool type flow, the coefficient of discharge (C) in the case of flow over only on the notch tends to increase linearly in comparison with C=0.6 by the effect of approaching velocity, when the value of L/PL becomes above 0.3. On the other hand, the the flow over on the triangular type weir of the pool-type flow tends to be approximate to flow over a triangle weir and the experimental equation can be obtained in the pool type flow.