تاثیر سیم اغتشاش ساز بر تنش برشی رینولدز و سرعت‌های نوسانی در سیلندر دایروی

نوع مقاله : علمی پژوهشی

نویسندگان

1 کارشناسی ارشد، گروه مهندسی مکانیک، دانشگاه حکیم سبزواری، سبزوار

2 دکتری، گروه مهندسی مکانیک، دانشگاه حکیم سبزواری، سبزوار

3 استاد، گروه مهندسی مکانیک، دانشگاه حکیم سبزواری، سبزوار

چکیده

بررسی جریان حول سیلندر دایروی از مسائل کلاسیک مکانیک سیالات به شمار می رود. نیرو‌‌های ناپایدار تشکیل شده در پشت سیلندر، ناشی از گردابه‌ های جدا شده از سطح آن است. کنترل شدت ریزش گردابه ‌‌ها منجر به کنترل شدت نیرو‌های ناشی از گردابه ‌‌ها می‌‌شود. یکی از نمونه تجهیزاتی که در کاهش نوسانات ناشی از گردابه ‌ها مورد استفاده قرار می‌گیرد، سیم اغتشاش ساز می ‌باشد. لذا در پژوهش حاضر، سرعت ‌های نوسانی، تنش برشی رینولدز و ضریب پسا حول سیلندر دایروی همراه با سیم اغتشاش ساز در اعداد رینولدز 3900 و 13692 و 27383 بررسی شد. بدین منظور قطر سیلندر مورد پژوهش 20 میلی متر و قطر سیم ‌های اغتشاش ساز نصب شده 25/0، 5/0، 75/0، 1 و 5/1 میلی ‌متر می‌‌باشد. سیم ‌های اغتشاش ساز در موقعیت‌ های140± و40  θ= ±درجه نصب شده‌‌ اند. نتایج حاصل نشان می‌ دهند که استفاده از سیم‌ اغتشاش ساز با قطر 25/0 میلی‌ متر منجر به کاهش 68%، 50% و 55% سرعت‌ های نوسانی   و کاهش 85% تنش برشی رینولدز نسبت به سیلندر صاف می‌ شود. همچنین وجود پیک در نمودارهای سرعت نوسانی بیانگر وجود گردابه‌ های بزرگ در پشت سیلندر می ‌‌باشد. تنش برشی رینولدز  با قطر سیم اغتشاش ساز رابطه مستقیم دارد.

کلیدواژه‌ها

موضوعات


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