بررسی آزمایشگاهی اثر محل قرارگیری مانع متخلخل پیوسته سه بعدی در کف پله سرریز پلکانی بر مشخصات جریان عبوری
محورهای موضوعی : مقالات برگرفته از پایان نامه
سید امین اصغری پری
1
(دانشیار گروه عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی خاتم الانبیاء بهبهان، بهبهان، ایران .)
آذین رزمخواه
2
(دانشجوی کارشناسی ارشد مهندسی عمران آب، سازه‌های هیدرولیکی، دانشکده فنی و مهندسی، دانشگاه صنعتی خاتم الانبیاء بهبهان، بهبهان، ایران.)
سید علی اصغری پری
3
(استادیار گروه عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی خاتم الانبیاء بهبهان، بهبهان، ایران.)
مجتبی کردناییج
4
(مدرس گروه عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی خاتم الانبیاء بهبهان، بهبهان، ایران .)
کلید واژه: سرریز پلکانی, مانع متخلخل سه بعدی, استهلاک انرژی, تکنیک BIV,
چکیده مقاله :
چکیده مقدمه: در تحقیق حاضر به بررسی اثر محل قرارگیری و ارتفاع مانع متخلخل سه بعدی (دارای تخلخل در هر سه بعد) که بهصورت پیوسته در عرض فلوم بر روی کف پله قرار گرفته است و همچنین اثر تعداد پلههای دارای این نوع مانع متخلخل بر روی سرریز پلکانی پرداخته شده است. روش: شیب سرریز 1:2 و دارای 8 پله، ارتفاع کلی 87 سانتیمتر و عرض فلوم 1.2 متر بوده است. ابزارهای اندازهگیری در تحقیق حاضر عمق سنج، تکنیک پردازش تصویر و مشاهدات زمان انجام آزمایش بوده است. یافته ها: در مانع متخلخل سه بعدی پیوسته با توجه به ارتفاع نسبی، محل قرارگیری و تعداد پلههای دارای مانع، مرزهای شروع جریان قرارگیری نسبت به حالت شاهد تغییر میکند بهطوریکه با افزایش فاصله نسبی مانع از لبه پلکان و کاهش تعداد پلههای دارای مانع متخلخل پیوسته، تمایل جریان به گسترش در محدوده بالایی جریان انتقالی (همسایگی با جریان رویهای) افزایش مییابد. نتیجه گیری: در رژیم جریان ریزشی قرارگیری مانع متخلخل سه بعدی برای متغیرهای تحقیق حاضر سبب افزایش استهلاک انرژی تا 5 درصد بیشتر نسبت به حالت شاهد میگردد. برای رژیمهای جریان انتقالی و رویهای در اکثر موارد قرارگیری مانع متخلخل پیوسته اثر استهلاکی مثبت ندارد. همچنین با توجه به اندازههای ناحیههای شکل گرفته حاصل از BIV میتوان بیان کرد که در شرایطی که ناحیه اختلاط اندازهگیری شده در دو پله متوالی نسبت به حالت شاهد دارای مقدار بیشتری بوده است، استهلاک انرژی نیز افزایش یافته است.
Abstract Introduction: In the present study, we investigated the effect of the location and height of a three-dimensional porous obstacle (with porosity in all three dimensions) which is located on the bottom of the steps in the width of the flume and the number of steps with this type of obstacle has been investigated on a stepped spillway. Methods: The slope of the spillway was 1: 2 and had 8 steps, the total height was 87 cm and the width of the flume was 1.2 m. The measuring instruments in the present study were point gage, image processing technique and observations of the experiment. Findings: In a continuous three-dimensional porous obstacle, according to the relative height, location and number of steps with an obstacle, the starting flow boundaries of the placement change compared to the flat step, so that by increasing the relative distance of the obstacle from the edge of the steps and decreasing the number of steps with continuous porous obstacle. The tendency of the flow to expand in the upper range of the transition flow (neighborhood with the skimming flow regime) increases. Conclusion: In the nappe flow regime, the placement of a three-dimensional porous obstacle for the variables of the present study increases the energy dissipation by up to 5% more than in the flat step (control). For transitional and skimming flow regimes, in most cases, continuous porous obstacle placement has no positive depreciation effect. In addition, according to the size of the areas formed by BIV, it can be said that in conditions where the mixing area measured in two consecutive steps was more than the flat step, energy dissipation has also increased.
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