بررسی عددی شرایط هیدرولیکی جریان در مستهلک‌کننده‌های جامی و تاثیر نوع جریان ورودی و شکل هندسی بر آن

یکی از روش های کاستن انرژی آب در صنعت سد سازی، استفاده از سازه‌های مستهلک کننده مانند پرتاب کننده‌های جامی شکل است. در این پژوهش رفتار جریان آب در جام سد آزاد با استفاده از نرم‌افزار flow-3d با در نظر گرفتن عدم اختلاط آب و هوا مدل‌سازی شد و پس از انتخاب مدل‌های آشفتگی مختلف، مدل k-ε با خطای پارامترهای فشار، سرعت و عمق به ترتیب 1.52، 1.5 و 1.58 درصد انتخاب گردید و پس از آن اعداد فرود 2 تا 7 در مقطع ورودی به جام ایجاد گردید. نتایج مربوطه با نسبت‌های بی‌بعد عدد فرود و x/r در مرکز و کناره‌ها مقایسه شده که سرعت در طول جام به‌طورکلی روندی افزایشی کمی داشته و در انتهای آن به حداکثر خود می‌رسد و با افزایش اعداد فرود روندی معکوس دارد، عمق در طول تقریباً ثابت بوده و در انتها به حداقل خود می‌رسد و با افزایش عدد فرود کاهش می‌یابد. فشار در طول جام روندی کاهشی داشته و با افزایش عدد فرود کاهش می‌یابد. محدوده اعداد فرود ماقبل نهایی ورودی به پرتاب‌کننده (که تنداب قادر است تولید نماید) نقطه عطف تغییر شرایط هیدرولیکی جریان است که این مهم باید در طراحی این سازه مدنظر قرار گیرد. نهایتاً می‌توان گفت که آسیب-پذیرترین منطقه پرتاب‌کننده محدوده 0/3

the numerical investigation of hydraulic condition on flip bucket spillways and effect of inlet flow and shape on it

introductionsince beginning of the dam construction industry, one of the challenges that engineers have always been involved with, is how to reduce the enormous energy of water when it overflows from dams for which, many plans and ideas have been presented so far. one of these ideas is to utilize the energy dissipater structures among which, the flip buckets are well-known. since the flip bucket is one of the most important components of a dam, whose destruction disrupts the normal performance of the dam, the engineers have always tried to enhance the efficiency of this component by investigating into the hydraulic conditions such as pressure, depth and velocity. accordingly, it is of paramount significance to comprehensively study the hydraulic performance and condition of the flip bucketsmethodologyin this study, behavior of the fluid in the flip bucket of a dam has been modeled using flow-3d software. the obtained results in froude number, were compared with the data derived from an existing physical model. after determining the error percentage and selecting the turbulence model etc., using the continuity and motion equations in the fluid dynamics and finite volume method, a model was built and through a trial-and-error process, froude numbers ranging from, 2 to 7 were chosen. the results pertained to the velocity, static pressure and depth were captured and compared with geometric characteristics of the bucket and incoming flow condition. to efficiently employ the results, the produced graphs were normalized using a similitude analysis. the comparisons have been made with the non-dimensional ratios of froude number and x/r (x: distance from the bucket and r: bucket radius) in the middle as well as right and left sidesresults and discussionin order to choose the turbulence model (k-ε, k-ω and rng turbulence models were used to compare the results of various models according to previous studies), after analyzing and optimizing the computational error between the numerical and the physical models, the k-ε model with the minimum rate of error was selected as the best practice. it needs to be noted that the error rate of pressure, velocity and depth are 1.52%, 1.5% and 1.58%, respectively. the results indicated that the velocity changes along the length of the bucket, generally have a slight increasing trend and reach their maximum value at the end of the bucket. in addition, velocity changes have an inverse trend as the froude number increase. moreover, it was observed that the depth changes are almost constant along length of the bucket and reach their minimum value at the end and decrease with the depth as the froude number increases. pressure changes also have a decreasing trend along the length of the bucket and also, decrease with increase in the froude number. the situation of the above parameters in the sides is generally similar to the middle axis, but with a greater intensityconclusionit can be generally stated that the most vulnerable zone of the flip bucket is where 0.1