شبیه‌سازی عددی جریان جابجایی اجباری آرام همراه با آنالیز تولید انتروپی در یک کانال دارای دو انبساط ناگهانی - روش انسداد کردن

نوع مقاله : مقاله مکانیک

نویسندگان

1 باشگاه پژوهشگران جوان و نخبگان، واحد سیرجان، دانشگاه آزاد اسلامی، سیرجان، ایران

2 استادیار، دانشکده مهندسی مکانیک، دانشگاه صنعتی سیرجان، سیرجان، ایران

چکیده

در تحقیق حاضر، شبیه ‌سازی عددی جریان جابجایی اجباری آرام همراه با آنالیز تولید انتروپی، در یک کانال دو بعدی و دارای دو انبساط ناگهانی مورد مطالعه قرار می‌گیرند. این دو انبساط، توسط چهار پله‌ شیب‌دار پسرو ایجاد شده و باعث به وجود آمدن جدایش جریان و نواحی گردابه‌ای می‌شوند. نواحی گردابه‌ای ایجاد شده در کانال نیز، بطور قابل توجه‌ای بر نرخ انتقال حرارت و میزان بازگشت ناپذیری جریان تأثیر می‌گذارند. اندازه زاویه شیب پله‌ها، یکی از مهم‌ترین پارامترهای مؤثر بر کنترل نواحی گردابه‌ای، نرخ انتقال حرارت و میزان بازگشت ناپذیری جریان است. در این مطالعه، بعد از محاسبه میدان‌های سرعت و دما، به بررسی اثرات شیب پله بر نواحی جدایش جریان، ضریب اصطکاک، عدد ناسلت، عدد تولید انتروپی و عدد بژان پرداخته می‌شود. برای محاسبه میدان‌های سرعت و دما، معادلات حاکم شامل معادلات بقای جرم، ممنتوم و انرژی برای جریان تراکم ناپذیر و پایا با استفاده از روش‌های حجم محدود و تکنیک‌های دینامیک سیالات محاسباتی حل می‌شوند. برای شبیه‌سازی سطوح شیب‌دار پله‌های پسرو در مختصات کارتزین، از روش انسداد کردن (روش ناحیه غیر فعال)، استفاده می‌شود. همچنین، با استفاده از روابط مربوط به آنالیز قانون دوم ترمودینامیک، به محاسبه‌ی تولید انتروپی و میزان بازگشت ‌ناپذیری جریان سیال پرداخته می‌شود. در نهایت، تأثیر عدد بریکمن بر عدد تولید انتروپی و عدد بژان به‌صورت نموداری بررسی می‌شود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Numerical simulation of laminar forced convection flow with entropy generation analysis in a duct with two expansions - Blocked-off method

نویسندگان [English]

  • Shima Sotoodehnia 1
  • Nasrin Aminizadeh 2
  • Meysam Atashafrooz 2
1 Young Researchers and Elite Club, Sirjan Branch, Islamic Azad University, Sirjan, Iran
2 Department of Mechanical Engineering, Sirjan University of Technology, Sirjan, Iran
چکیده [English]

In the present paper, numerical simulations of laminar forced convection flow and entropy generation analysis in a 2-D duct with two sudden expansions are investigated. These two expansions are created by four inclined backward facing steps and beget the separation flows and vortex regions. The vortex regions have the significant effects on the heat transfer rates and flow irreversibility. The inclination angle of steps is one of effective parameters on the control of the separation flows, heat transfer rates and flow irreversibility. In this paper, after calculation of velocity fields and temperature distributions, the effect of the step inclination angle on the separated flows, Nusselt number, friction coefficient, entropy generation number and Bejan number is studied. To obtain the temperature distributions and velocity fields, the set of governing equations including mass, momentum and energy equations are solved by the finite volume methods and computational fluid dynamic (CFD) techniques. For simulating the inclined surfaces of steps in Cartesian coordinates, the blocked-off method is used. Also, thermodynamic second law analysis is employed to calculate the entropy generation and flow irreversibility. Finally, the effect of the Brickman number on the entropy generation number and Bijan number is investigated graphically.

کلیدواژه‌ها [English]

  • Entropy Generation
  • Laminar Forced Convection
  • Inclined Step
  • Blocked off Method
  • Computational Fluid Dynamic (CFD)

مراجع

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مدل سازی در مهندسی
دوره 17، شماره 56
اردیبهشت 1398
صفحه 73-83

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سابقه مقاله

  • تاریخ دریافت: 21 فروردین 1394
  • تاریخ بازنگری: 06 فروردین 1397
  • تاریخ پذیرش: 11 اردیبهشت 1397

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