عنوان مقاله [English]
One of the most common energy dissipator structures, is the hydraulic jump-type stilling basins, in which the flow excess kinetic energy is dissipated by generation of a hydraulic jump, changing the flow regime from super- to subcritical flow. Due to the extensive use of stilling basins in hydraulic systems and irrigation and drainage networks, their study was the focus of several investigations. For the hydraulic design of stilling basins, three parameters, including the length, sequent depth and head loss of the jump, are the major parameters having great effects on designing economical stilling basins.
In the present study, analytical and experimental investigations were performed to study the profile of circular hydraulic jumps on slopped beds with adverse slope. The study mainly focused on the conjugate depth ratio, relative head loss and relative length. In the analytical model, we applied a series of reasonable assumptions and used integral equations governing the fluid dynamics to derive relationships for the conjugate depth ratio and the relative head loss, which are applicable for both classical and circular hydraulic jumps. Experimental study was carried out in a cubic reservoir, in which a circular bed of 2 m in diameter was applied as the circular bed in its center. In the experimental study, flow discharge, initial and secondary depth and length of the jump were measured. According to the results, by increasing the ratio of the conjugate radius (Ro) and the bed slope (So), the ratio of the conjugate depth and jump length decrease and the relative head loss increases. The accuracy of the analytical relationships compared to the experimental was checked, applying four error functions including R2, NRMSE, WQD and EF, showing a relatively good correlation between the experimental and the analytical results. Furthermore, using the experimental data, the length of the circular hydraulic jump were investigated. Results show that in this type of jump, the length of the hydraulic jump is approximately half the classical hydraulic jump.