Document Type : Research Paper
Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, East Azarbaijan, iran.
M.sc graduate, Department of civil engineering, Faculty of engineering, University of Maragheh, Maragheh, Iran
M.sc student, Department of civil engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran
The present study investigates for the first time the hysteretic behavior of a supercritical flow that can occur in a channel near additional structures such as a sill in an experimentally. For this purpose, three sills with cylindrical, rectangular cubic, and pyramidal geometries have been used. In this study the discharges used are in the range of 250 to 600 liters per minute. First the discharge enters the laboratory flume increasingly in the primary flow and then decreasingly in the secondary flow. Possible flow regimes near the sill are classified based on the relative depths in sections 1 and 2 as a function of the Froude number under the gate. The results showed that by increasing the flow discharge and then decreasing it, in the same discharges, two different flow behaviors are observed in the same laboratory conditions. The results also showed that the relative depth values of y1/y0, y2/y0, and the Froude numbers of sections 1 and 2 were greatly increased, while the hydraulic jump efficiency for the relative energy dissipation parameter at the rectangular cubic sill was higher than the other sills. The efficiency of hydraulic jump at the rectangular cube sill is higher than other sills, which is a relative increase of 72%. So that in the primary flow, the amount of these depths indicates the subcritical regime and in the secondary stream, with the formation of the phenomenon of hysteresis in some discharges, it indicates the supercritical regime.