مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

مطالعه عددی اثر ضریب انعکاسی در شبیه‌سازی اویلری-اویلری هیدرودینامیک بستر سیال فورانی

نوع مقاله : مقاله پژوهشی

نویسنده
گروه مهندسی مکانیک، دانشکده مهندسی مکانیک و مواد، دانشگاه صنعتی بیرجند، بیرجند، ایران
10.48311/mme.2026.118839.82944
چکیده
هیدرودینامیک جریان دوفازی گاز-جامد در بستر سیال فورانی به صورت عددی با مدل اویلری-اویلری بررسی شده است. در این پژوهش اثر ضریب انعکاسی مورد مطالعه قرار گرفته که بیانگر میزان انتقال تکانه مماسی برخورد ذره -دیوار است. شبیه‌سازی به صورت دوبعدی با استفاده از تئوری جنبشی جریان دانه‌ای برای فاز جامد انجام و نتایج حاصل با داده‌های تجربی و عددی دیدگاه اویلری-لاگرانژی مقایسه شده است. مقادیر مختلف ضریب انعکاسی (005/0، 01/0، 05/0 و 5/0) در نظر گرفته شده و اثر آن روی هیدرودینامیک جریان دوفازی گاز-جامد در ارتفاع‌های مختلف بستر بررسی شده است. با مقایسه نتایج روش حاضر با شبیه‌سازی اویلری-لاگرانژی مطالعات پیشین، بیشترین اختلاف برای متوسط زمانی شار جرمی عمودی ذرات در مرکز بستر 6.5% و در نزدیکی دیوار 18.1% مشاهده شد. اختلاف بین نتایج متوسط زمانی سرعت عمودی هوا در مرکز بستر از 5.7% تا 20.4% برای ارتفاع‌های مختلف بدست آمد. از مهمترین دلایل تفاوت بین نتایج می‌توان به تأثیر کمیت‌هایی مانند تابع پسا، ضرایب بازگشت جامد، مدلهای فشار و لزجت جامد اشاره کرد که در این پژوهش بررسی نشده است. یافته‌ها نشان می‌دهد افزایش ضریب انعکاسی سبب افزایش اصطکاک بین ذره و دیوار و در نتیجه کاهش کسر حجمی فاز جامد و کاهش سرعت جامد در نزدیکی دیوار می‌شود. با توجه به داده‌های بدست آمده، مقدار ضریب انعکاسی 05/0 و 5/0 بهترین انطباق را با نتایج آزمایشگاهی و مدل اویلری-لاگرانژی نشان می‌دهد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Numerical study of the effect of specularity coefficient in Eulerian–Eulerian simulation of spouted fluidized beds

نویسنده English

Hamed Khosravi-Bizhaem
Department of Mechanical Engineering, Faculty of Mechanical and Materials Enginering, Birjand University of Technology, Birjand, Iran
چکیده English

The hydrodynamics of gas–solid two-phase flow in a spouted fluidized bed was numerically investigated using the Eulerian–Eulerian model. In this study, the effect of the specularity coefficient, which represents the degree of tangential momentum transfer during particle–wall collisions, was examined. Two-dimensional simulations were carried out using the kinetic theory of granular flow for the solid phase, and the obtained results were compared with available experimental data as well as numerical results based on the Eulerian–Lagrangian approach. Different values of the specularity coefficient (0.005, 0.01, 0.05, and 0.5) were considered, and their effects on the hydrodynamics of gas–solid flow at different bed heights were analyzed. By comparing the present results with previous Eulerian–Lagrangian simulations, the maximum deviation in the time-averaged vertical particle mass flux was found to be 6.5% at the bed center and 18.1% near the wall. In addition, the differences in the time-averaged vertical air velocity at the bed center ranged from 5.7% to 20.4% at different heights. These discrepancies can be attributed to factors such as the drag correlation, solid restitution coefficients, and solid pressure and viscosity models, which were not examined in the present study. The results indicate that increasing the specularity coefficient enhances particle–wall friction, leading to a reduction in the solid volume fraction and solid velocity near the wall. Based on the obtained data, specularity coefficients of 0.05 and 0.5 show the best agreement with experimental measurements and Eulerian–Lagrangian model predictions.

کلیدواژه‌ها English

spouted fluidized bed؛ specularity coefficient؛ gas-solid flow؛ Eulerian&ndash
Eulerian
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