Hydraulic Analysis of Composite Hydraulic Structure Considering Existing of Pire

A composite hydraulic structure is used to solve the problems of sediment and floating materials, respectively. A pier (obstacle) is used at the downstream of the composite hydraulic structure to increase water depth, decrease flow velocity, and dissipate the flow energy. The paper deals with the effect of single pier and double piers on the hydraulic characteristics of the composite structure. Circular and square shapes are adopted in the study with different spacing measured from the downstream of the composite structure. The experiments reveal how the level of the hydraulic characteristics is changed due to the existence of the pier/piers as compared to without the existence of the pier/piers. The statistical data which is collected from the experiments shows the alteration in the average downstream water depth, discharge coefficient, Reynolds number, upstream Froude number and downstream Froude number regardless of pier shape and spacing. The alteration happens owing to a change in the separation zone of water flow along the pier circumference. Nonlinear water surface profile is appeared when the pier is located at the downstream, while linear water surface profile is appeared clearly when the downstream without pier. Also the interference between overflow velocity and underflow velocity will be reflected in the hydraulic characteristics.