Comparison of Flow Characteristics and Energy Dissipation in Vertical Drop Structures with Aerated and Non-Aerated Flow

Abstract ―​

Vertical drop structures, owing to their simple construction and effective performance, are common hydraulic features employed in irrigation networks, erodible waterways, and watersheds for managing flow energy. In these structures, the occurrence of a hydraulic jump downstream, a critical parameter for energy loss akin to most energy-consuming structures, significantly influences the overall waste of energy. The dissipation of energy transpires due to the flow's impact on the pond, along with alterations in flow lines and the turbulence generated in the pond beneath. Another crucial component contributing to energy loss is the jet, referred to as "jet energy loss" in this study. Properly sizing the slope-breaking structure in accordance with the hydraulic characteristics of the flow is crucial, with special attention to mitigating jet energy loss. The incorporation of continuous slope breakers in the flow path can notably reduce operational costs. This research investigates flow parameters by constructing vertical drop structures at two heights, namely 5.15 cm and 5.25 cm. The study focuses on flow conditions with non-aerated jets and compares the findings with similar studies conducted in aerated flow conditions by researchers such as Rajaratnam, White, Rand, and Moore. The results indicate variable dissipation levels dependent on the number of slope breakers, with higher dissipation observed in non-aerated states compared to aerated states. For the non-aerated state, the dissipation ranges from approximately 6.6% of total flow energy for Dn equal to 0.36 to 57% for Dn above 0.003.