بررسی هندسه آبشستگی در حوضچه مستهلک کننده پایین‌دست سرریز سیفونی

نویسندگان

دانشگاه آزاد اسلامی

چکیده

از جمله سازه‌های اقتصادی مستهلک کننده انرژی جریان عبوری از روی سرریز‌های بلند، پرتابه‌های جامی هستند که جریان ریزشی باعث وقوع آبشستگی در حوضچه پایین‌دست آنها می‌شود. در این تحقیق تغییرات بستر حوضچه بصورت حفره آبشستگی در پایین‌دست سرریز سیفونی همراه با پرتابه مورد بررسی قرار گرفته است. ابعاد و موقعیت به صورت آزمایشگاهی و تئوریکی آنالیز شدند. نتایج آزمایشگاهی نشان داد بیشینه عمق آبشستگی تابعی از شدت جریان و عمق پایاب است. هم‌چنین زاویه پرتاب باکت روی فاصله‌های پشته بالادست و کف حفره از لبه سرریز بیشترین تاثیر را داشت. طول حفره، فاصله انتهای پشته پایین‌دست تا لبه سرریز و فاصله بیشینه عمق آبشستگی تا لبه سرریز تابعی از شرایط هیدرولیکی بودند و کمترین تاثیر را از زاویه پرتابه و اندازه ذرات رسوبی بستر داشتند. ارتفاع پشته بالادست ضریب همبستگی زیادی با زاویه پرتابه دارا بود. ارتفاع پشته پایین‌دست متاثر از دبی و عمق پایاب بود. بر مبنای تحلیل تئوریکی و با استفاده از تئوری پی باکینگهام معادلات خطی سه متغیره برای پیش‌بینی خصوصیات ابعاد و موقعیت حفره و پشته‌ها بدست آمد. مقایسه نتایج حاصل از مقادیر پیش‌بینی و اندازه‌گیری شده موید دقت مناسب معادلات استخراج شده بود.

کلیدواژه‌ها


عنوان مقاله [English]

Scour Hole Geometry Surveying in Plunge-Pool Downstream of Siphon Spillway

نویسندگان [English]

  • Arash Khairollahi
  • mehdi fuladipanah
Department of civil engineering, ramhormoz branch, islamic azad university, ramhormoz, iran
چکیده [English]

One of the economical energy dissipater structures applying in high spillways is flip-bucket which falling flow causes scouring in plunge-pool at downstream. In this research, the bed variation as a scour hole at the downstream of a siphon spillway has been investigated. Dimensions and position of the scour hole were analyzed both experimentally and theoretically. The experimental results showed that the maximum scour hole depth was a function of discharge rate and downstream tail water depth. Also, flip-bucket angle had the most significant effect on distances of upstream hill and scour hole bottom from the spillway. It was found that the scour hole length, distances of downstream hill end point and maximum scour from the spillway were affected by the hydraulic conditions but they were less effected by the flip bucket angle and bed particle size. Also, it was seen that the flip bucket angle had a significant effect on upstream hill height. The height of downstream hill height was a function of flow discharge and tail water. Applying Buckingham π-theory, three variable linear equations were extracted to predict the dimension and situation of the scour hole and hills. The comparison between the measured versus the predicted values showed a good agreement between them.

کلیدواژه‌ها [English]

  • Dimensional Analysis
  • Flip Bucket
  • Plunge Pool
  • Sour Hole
  • Siphon Spillway
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