FLOW – COMPOSITE HYDRAULIC STRUCTURE – LONGITUDINAL OBSTACLE INTERACTION

Abstract

A composite hydraulic structure can be described as a discharge structure constructed inside a river or an open channel. This experimental study is targeted at investigating the performance of the composite hydraulic structure in consideration of the existence of the longitudinal obstacle in the downstream region of the composite hydraulic structure. This study adopts two different lengths of the longitudinal obstacle. In addition, three different cross-sectional areas of the obstacle in the lateral direction are adopted. Also, the gate of a composite structure has a half-ellipse shape, while the weir of a composite structure has rectangular, triangular, and parabolic shapes, respectively. Seven cases are investigated experimentally. Here, six cases included the longitudinal obstacle, while the last case was without it. The influence of downstream Froude number on the average downstream water depth, downstream flow velocity, upstream Froude number, Reynolds number, and actual discharge is investigated. Also, the relationship between Reynolds number and downstream flow velocity, actual discharge and downstream flow velocity, discharge coefficient and upstream Froude number, discharge coefficient and Reynolds number, discharge coefficient, and actual discharge is investigated, respectively. The results illustrated that the longitudinal obstacle has a moderate influence on the hydraulic characteristics of the composite hydraulic structure regardless of the obstacle length and the obstacle cross-section area. Finally, the hypothesis test is performed to demonstrate the feasibility of the longitudinal obstacle.