مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی عددی اثرات هندسه ی ایرفویل بر ساختارهای جریانی در یک فن زیرصوتی با کمک روش شبیه سازی گردابه های بزرگ

نویسندگان
1 دانشجوی دکتری، دانشگاه تربیت مدرس
2 استادیار دانشگاه تربیت مدرس
چکیده
در این مقاله شبیه‌سازی جریان در گذرگاه بین پره‌ا‌ی یک فن زیرصوتی با ایجاد تغییراتی در هندسه ایرفویل پره، در شرایط نزدیک به رخداد استال گردشی، به روش عددی بررسی شده است. الزامات شبیه‌سازی جریان با هدف آشکارسازی طیف آشفتگی در جریان اطراف پره، بررسی شده است. با توجه به شروع بسیاری از ناپایداری‌های آیرودینامیکی از لبه حمله پره و تاثیر هندسه این قسمت در شکل گیری نوع و شدت ناپایداری‌ها، هدف این پژوهش، بررسی اثرات تغییر در شعاع نوک ایرفویل پره‌ی فن در رخداد پدیده‌های جریانی با مقیاس‌های مختلف اعداد موج است. حل عددی میدان جریان به روش‌های مختلف مدل‌سازی و شبیه‌سازی عددی آشفتگی انجام شده و توانمندی روش‌های گوناگون در آشکارسازی پدیده‌های جریان مشخص شده است. ایرفویل به کار رفته در هندسه‌ی پره در پژوهش‌های پیشین، از سری NACA-65 استاندارد است، که در این پژوهش با %50 تغییر شعاع لبه حمله‌، تاثیر هندسه‌ی پره بر ساختار جریان بررسی شده است. همچنین الزامات شبکه در شبیه‌سازی عددی به طور ویژه بررسی شده و پیشنهادهایی برای استفاده در فرآیندهای شبیه‌سازی آیروالاستیسیته ارائه شده است. در کار حاضر، سطح دقت و قابلیت اتکا به نتایج به دست آمده با روش شبیه-سازی گردابه‌های بزرگ، با بررسی طیف انرژی و تخمین میزان انرژی آشکار شده مورد توجه قرار گرفته است. نتایج نشان‌دهنده‌ی اثر گذاری دقت حل و تراکم شبکه به طور خاص بر پدیده‌های مقیاس کوچک و طیف جریان است. همچنین تغییر در هندسه پره، بر توزیع طیفی انرژی میان پدیده‌های مقیاس کوچک، اثر قابل توجهی داشته است.
کلیدواژه‌ها

عنوان مقاله English

Numerical investigation of airfoil geometric variations impacts on flow structures in a subsonic fan using Large Eddy Simulation method

نویسندگان English

Mahmood Asgari Savadjani 1
Behzad Ghadiri 2
1 Tarbiat Modares University-PhD Candidate
2 Tarbiat Modares University
چکیده English

The numerical simulation of near-stall condition in a passage of an isolated subsonic rotor is studied in detail. The requirements of numerical simulation in order to resolve turbulent spectra around the blade are studied. According to the fact that most of unsteady aerodynamic phenomena incept from blades leading edge, and the role of this part in types and intensity of instabilities, the goal of this paper is to investigate the effects of changes in radius of leading edge of airfoil on flow phenomena in different scales of wave numbers. The governing equations of flow-field are solved using different numerical approaches. Resolution characteristics of different modeling and simulation techniques are investigated. The primary geometry of blade uses a standard NACA-65 series airfoil, which has been tolerated by 50% variation in circular leading edge radius. Mesh requirements of flow simulation for intended purposes are studied in detail and some recommendations are proposed to be implemented in numerical aeroelastic simulations. Accuracy and fidelity of LES results are studied with extraction of power spectra around the blade and the portion of resolved energy is also estimated. Results suggest that the order of accuracy and grid density highly affect the small-scale flow phenomena. The variations in leading edge radius also have great effect on energy distribution among resolved scales.

کلیدواژه‌ها English

Aeroelasticity
Large Eddy Simulation
Turbulent
Stall
Axial Compressor
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