عنوان مقاله [English]
In this study,, two Ogee Spillways with elliptical crest and USBR were simulated in both vertical upstream face state and inclined one with slope 3H:3V for three different heads He / Hd = 0.5, He / Hd = 1 and He / Hd = 1.33. and the results of changes in effective parameters such as flow rate, velocity and pressure were evaluated.
In this study, the results of Maynard’s Experimental model have been used to simulation and validate numerical results. The average errors of computed discharge compared with Maynard’s experimental data were less than 3%. Evaluation of the pressure field showed that at the head equal to the design head (He / Hd = 1), the pressures are close to atmospheric pressure and no negative pressure is created on the ogee crest, but at the head more than the design head there will be negative pressure on the overflow. the study of the pressure field showed that the amount of negative pressure in the USBR crest is higher than the amount of negative pressure in the elliptical crest, which is due to the lack of coherence in the crest and more separation of flow lines from it. The Ogee spillway with the elliptical crest has a relatively better performance in passing the flow and in these spillways, it is possible to pass more discharge with higher safety. Also inclining upstream face of spillway causes a change in the discharge coefficient and finally the flow rate through the spillway.