مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی عددی جذب انرژی از امواج نامنظم غیر خطی توسط استوانه بریستول

نویسندگان
1 دانشگاه فردوسی مشهد
2 دانشگاه صنعتی قوچان
3 دانشگاه فردوسی
چکیده
در این پژوهش رفتار استوانه جاذب انرژی امواج به عنوان یکی از سامانه‌های جذب انرژی تجدیدپذیر در برابر امواج نامنظم غیر خطی به صورت عددی و با استفاده از حل کامل معادلات ناویر-استوکس شبیه‌سازی شده است. برای این منظور از روش حجم کنترل و ترکیب آن با روش حوزه حل مجازی برای شبیه‌سازی و ردیابی جسم جامد در محیط سیال و از روش گام زمانی جزئی دو مرحله‌ای برای جداسازی معادلات پیوستگی و مومنتوم استفاده شده است. نتایج این پژوهش نشان می‌دهد که با وجود جذب انرژی توسط استوانه بریستول در دو راستای عمودی و افقی، راندمان جذب انرژی توسط این استوانه در امواج نامنظم غیر خطی حدود 8 درصد می‌باشد. با توجه به بررسی صورت گرفته بر روی ثابت فنر و ضریب میرایی در سیستم جذب انرژی این استوانه مشخص شد که کاهش راندمان جذب انرژی در این سامانه‌ها به علت محدود بودن فرکانس طبیعی این سیستم به یک فرکانس مشخص می‌باشد. همچنین نتایج نشان می‌دهد که در امواج با تیزی و عمق زیاد، راندمان حداکثر جذب انرژی در ثابت فنر بیشتر و ضریب میرایی کمتر و در امواج با عمق و تیزی متوسط، راندمان حداکثر در ثابت فنر کمتر و ضریب میرایی بیشتر رخ خواهد داد. بنابراین جهت جذب انرژی حداکثر از امواج نامنظم غیر خطی، علاوه بر تعیین دقیق این ضرایب بر اساس دوره تناوب و ارتفاع موج برخوردی با استوانه، استفاده از سامانه‌های جذب انرژی با چند فرکانس طبیعی و یا استفاده همزمان از چند استوانه با فرکانس‌های طبیعی مختلف پیشنهاد شده است.
کلیدواژه‌ها

عنوان مقاله English

A Numerical Investigation on Energy Absorption from Nonlinear Irregular Water Waves using Bristol Cylinder

نویسندگان English

Mehran Saadatinasab 1
Morteza Anbarsooz 2
Mohammad Passandideh-Fard 3
1 Ferdowsi University of Mashhad
2 Department of Mechanical EngineeringQuchan University of Technology
3 Ferdowsi University of Mashhad
چکیده English

In this study, the performance of a cylinder absorbing wave energy from irregular incident waves, as one of the renewable energy systems, is investigated numerically using complete solution of the Navier-Stokes equations. For this purpose, the control volume approach in conjunction with the fictitious domain method, for modeling the solid object motions inside fluid, are used where a two-step projection method is used to solve the governing equations. The results show that despite the cylinder absorbs energy in two main directions, its energy absorption efficiency in irregular waves is about 8%. Due to the employed spring and damper in these devices, the system has only one natural frequency which is the reason for its low efficiency at irregular waves. Results also show that for steep waves at deep waters, the maximum efficiency occurs at larger spring coefficient and smaller damping coefficients, while at moderate water depths and wave steepness, the maximum efficiency occurs at smaller spring coefficients and larger damping coefficients. Therefore, to reach maximum energy absorption efficiency at irregular waves, not only these coefficient has to be adjusted carefully, but also it is recommended to use multi-resonance systems or several cylinders with different natural frequencies.

کلیدواژه‌ها English

Bristol cylinder
Nonlinear irregular waves
Wave energy absorber
Fictitious domain method
Energy absorption efficiency
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