علوم کاربردی و محاسباتی در مکانیک

علوم کاربردی و محاسباتی در مکانیک

شبیه سازی گردابه های بزرگ جریان خنک کاری لایه ای تک مجرا و مجموعه سوراخ خنک کاری

نوع مقاله : مقاله پژوهشی

نویسندگان
یاسر طاهری 1
مهران رجبی زرگرآبادی 1
مهدی جهرمی 2
1 دانشکده مهندسی مکانیک، دانشگاه سمنان.
2 دانشگاه صنعتی مالک اشتر
10.22067/jacsm.2022.78932.1140
چکیده
در این مطالعه جریان خنک­کاری لایه­ای بر روی یک صفحه تخت به منظور بررسی اثرات به‌کارگیری مجموعه سوراخ بر اثربخشی خنک­کاری لایه­ای با استفاده از رهیافت RANS و LES شبیه­سازی شده است. هندسه­های مورد مطالعه شامل تک سوراخ استوانه­ای با قطر mm 1/11 و یک مجموعه سوراخ با 14 سوراخ استوانه­ای 97/2 میلی‌متری می­باشند، به طوری که سطح مقطع خروجی لوله خنک­کاری در هر دو حالت یکسان است. این مجموعه سوراخ به شکل ذوزنقه­ای چیدمان شده است. شبیه­سازی عددی در نسبت چگالی 6/1، نسبت طول به قطر 4، زاویه 35 درجه و نسبت دمش 25/1 صورت گرفته است. نتایج به دست آمده نشان می­دهند که جایگزینی یک تک سوراخ با مجموعه سوراخ شکل داده شده، منجر به افزایش قابل توجهی در اثربخشی خنک­کاری لایه­ای در هر دو جهت طولی و عرضی می­گردد، به طوری که افزایش در حدود 94 درصدی در میانگین سطحی اثربخشی خنک­کاری لایه­ای را در پی دارد. این افزایش در پی تغییر در ساختار گردابه­ها حاصل می­گردد. در مجموعه سوراخ خنک­کاری، مقیاس گردابه­های سنجاقی شکل کوچکتر از گردابه­های تک سوراخ است و شکل­گیری آنها در مکانی دورتر از سوراخ خنک­کاری صورت می­گیرد. در ساختار مجموعه سوراخ جفت گردابه­های anti-jet تشکیل می­شوند که جهت چرخش این گردابه­ها بر خلاف جهت CRVP است.
کلیدواژه‌ها
خنک‌کاری لایه‌ای
مجموعه سوراخ
شبیه‌سازی گردابه های بزرگ
ساختارهای منسجم
موضوعات

عنوان مقاله English

Large eddy simulation of single and multi-holes of film cooling

نویسندگان English

Yaser Taheri 1
Mehran Rajabi Zargarabadi 1
Mehdi Jahromi 2
1 Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
2 Malek Ashtar University of Technology, Tehran, Iran
چکیده English

  In this research, numerical studies have been performed by Reynolds averaged Navier Stokes (RANS) and large eddy simulations (LES) to investigate the effect of a novel film cooling design multi-holes on the film cooling effectiveness over a flat surface. A single cylindrical hole with 11.1 mm diameter and multi-holes (14 holes with a diameter of 2.97 mm) with fan configuration are considered for simulations. Numerical simulations are performed at a fixed density ratio of 1.6, length-to-diameter of 4, an inclined angle of 35o and blowing ratio 1.25. The results of the present study show that replacing a single hole with multi-holes results in a considerable increase in film cooling effectiveness in both axial and lateral directions, so that leads to an increase of about 94 percent in the area-averaged film cooling effectiveness. In the fan-shaped configuration, the scale of hairpin vortices is smaller than the single cylindrical hole, and forming of the vortices occurs in farther regions downstream of the hole. A pair of anti-jet vortices is formed in the structure of the multi-holes and the rotation direction of these vortices is opposite to the CRVP direction.
 

کلیدواژه‌ها English

film cooling
multi-holes
large eddy simulation
coherent structures
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