نوع مقاله : مقاله کامل پژوهشی
1 گروه مهندسی سیستمهای کشاورزی، واحد علوم و تحقیقات، دانشگاه آزاد اسلامی، تهران
2 گروه مهندسی و مدیریت منابع آب- عمران، واحد شهر قدس، دانشگاه آزاد اسلامی، تهران
عنوان مقاله [English]
Morning glory spillways are one of dam spillways. This type of spillway is so effective when there is no adequate space to build other types of spillways. The main problem with these spillways is the strong spiral vortices which will reduce efficiency of flood conveyance from the reservoir to downstream. Vortex breakers are attached on the crest spillway to reduce vortex negative functionality and increase efficiency of morning glory spillway and as a result it's discharge coefficient. In the present article, physical model of pyramidal vortex breakers has been undertaken. Number and characteristics of vortex breakers influence on the discharge coefficient of the morning glory spillway have studied. 165 experiments have been conducted in the Hydraulic Laboratory of SRBIAU, Tehran. Applying nonlinear regression analyses, emprical equations were obtained for estimating the discharge coefficient of morning glory spillway with pyramidal vortex breakers. Through comparsion of results of these new predictors and observed data, the determination coefficients of training and testing data was calculated as 0.917 in the crest control and 0.99 in the orifice control, respectively. The sensitivity analysis was also performed to investigate the effect of factors affecting the proposed predictors of the discharge coefficient. Finding show that pyramidal vortex breakers in group of six cause the discharge coefficient to be increased significantly. It is showed that the discharge coefficient due to triangular pyramidal vortex breakers existence is increased 50.97% in crest control and 11.80% in orifice control more than the non-vortex breakers in the morning glory spillway.