پهنه‌بندی خطر کاویتاسیون در تنداب سرریز سد سورک با الگوریتم طبقه‌بندی نزدیک‌ترین همسایه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش‌آموخته کارشناسی ارشد، دانشکده فنی و مهندسی، دانشگاه خوازمی، تهران، ایران

2 استادیار، گروه عمران، دانشکده فنی و مهندسی، دانشگاه خوارزمی، تهران، ایران

چکیده

کاویتاسیون یکی از عوامل خرابی تنداب سرریزها است که جهت کنترل این پدیده پهنه‌بندی خطر آن ضرورت دارد. در این تحقیق برای دستیابی به روشی جهت پهنه‌بندی خطر کاویتاسیون، از اطلاعات سرریز سد سورک در استان چهارمحال بختیاری استفاده شد. در روند مدل‌سازی ابتدا مدل هندسی سرریز ساخته شد و پس از شبکه‌بندی و اعمال شرایط مرزی، تحلیل جریان انجام شد. شاخص کاویتاسیون با توجه به مقادیر پارامترهای سرعت، ارتفاع جریان، شیب شوت و دیگر پارامترهای لازم، در 18 مقطع محاسبه گردید. نتایج حاصله از نرم‌افزار Flow-3D برای سنجش کیفی وضعیت خطر کاویتاسیون در تنداب سرریز سد سورک از دقت مناسبی برخوردار است؛ به‌طوریکه خطای RMSE فشار 2-10×26/0 پاسکال و سرعت2-10× 23/0 متربرثانیه نسبت به نتایج آزمایشگاهی بدست آمد. همچنین پارامترهای تاثیرگذار بر کاهش کاویتاسیون از قبیل زبری و هوادهی مورد بررسی قرار گرفت. نتایج نشان می‌داد در فاصله 70 تا 95 متری از تاج سرریز احتمال وقوع کاویتاسیون و خسارات ناشی از آن وجود دارد. نتایج تحلیل حساسیت نشان داد که استفاده از زبری یکنواخت 5/2 میلی‌متری و هوادهی در طول شوت موجب افزایش شاخص کاویتاسیون می‌شود. در این زبری مناطق مستعد وقوع کاویتاسیون به مقاطع پایین دست شوت جابجا می‌شوند. در زبری یکنواخت 5/1 میلی‌متر در طول کل سرریز، نتایج الگوریتم نزدیکترین همسایگی در دو مقطع پایانی 75/99 و 105 متری و در زبری یکنواخت 5/2 میلی‌متر در طول کل سرریز در دو مقطع 42 و 25/89 متری از تاج سرریز نسبت مدل Flow-3D بحرانی‌تر است که به معنی آسیب‌پذیری بیشتر این نواحی در مقابل پدیده کاویتاسیون است.

کلیدواژه‌ها

عنوان مقاله [English]

Zonation of cavitation hazard in the chute spillway of Surk dam with Nearest Neighbor Classification Algorithm

نویسندگان [English]

  • Amir Hossein Asadian 1
  • Seyed Shahab Emamzadeh 2
1 MSc student, Department of Civil Engineering, Kharazmi University, Tehran, Iran
2 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran.
چکیده [English]

Cavitation is one of the failure factors of spillways, which requires risk zoning to control this phenomenon. In this research, to obtain a method for zoning the risk of cavitation, the spillway information of Surk dam in Chaharmahal Bakhtiari province  was used. In the modeling process, first, the geometric model of the overflow was constructed and after meshing and applying boundary conditions, flow analysis was done. The cavitation index was calculated in 18 sections according to the values of flow velocity and height, chute slope, and other necessary parameters. The results of Flow-3D software for qualitative assessment of the cavitation risk situation in Surk dam spillway are of appropriate accuracy; Thus, the RMSE error of pressure 0.26×10-2 pascal and velocity 0.23×10-2 m/s was obtained compared to the laboratory results. Also, parameters affecting the reduction of cavitation such as roughness and aeration were investigated. The results showed that there is a possibility of cavitation and damage caused at a distance of 70 to 95 meters from the crest of spillway. The results of the sensitivity analysis showed that the use of a uniform roughness of 2.5 mm and aeration during the chute increases the cavitation index. This roughness moves the cavitation areas to the downstream sections of the spillway. Also, by creating a roughness of 1.5 mm in two end sections 99.75 and 105  meters from  the crest of spillway, the results of the nearest neighbor algorithm (NNA) showed a more critical state than the Flow-3D model. By applying a roughness of 2.5 mm, in the two end sections of 42 and 89.25 meters from the crest of spillway, the NNA showed a more critical state than the Flow-3D model, which means that these areas are more vulnerable to the cavitation phenomenon.

کلیدواژه‌ها [English]

  • Surk Dam
  • Flow3D
  • Cavitation
  • Nearest Neighbor Classification Algorithm
  • Chute spillway

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تحقیقات آب و خاک ایران
دوره 53، شماره 10
دی 1401
صفحه 2445-2462

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