مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

شبیه‌سازی CFD نحوه اثر شرایط عملیاتی در کیفیت اختلاط جریان دوفازی گاز-مایع در مخزن همزن‌دار

نویسنده
دانشکده مهندسی شیمی، نفت و گاز، پردیس شماره 1، دانشگاه سمنان، سمنان
چکیده
در این تحقیق چگونگی اثر شرایط عملیاتی بر نحوه توزیع فاز گاز در مخزن‌همزن‌دار دوفازی گاز-مایع با پره راشتون به کمک تکنیک دینامیک سیالات محاسباتی (CFD) مورد بررسی قرار گرفت. به منظور شبیه‌سازی رفتار جریان چند فازی در مخزن دو فازی گاز-مایع از دیدگاه اولری-اولری استفاده گردید. با توجه به هیدرودینامیک پیچیده و ماهیت جریان آشفته در مخزن همزن‌دار، رفتار جریان آشفته در مخزن بر اساس مدل RNG k-ε مدل شد. با بررسی شرایط عملیاتی بر اساس عدد بی‌بعد هوادهی و عدد رینولدز پره، چگونگی توزیع کسر حجمی فاز گاز در مخزن مورد بررسی قرار گرفت. نتایج نشان داد کمترین میزان ماندگی فاز گاز در ناحیه کف مخزن الی زیر پره و بیشترین میزان ماندگی فاز گاز در ناحیه اطراف پره شکل می‌گیرد. با افزایش عدد رینولدز پره مشاهده شد که کیفیت اختلاط در مخزن به علت تشکیل نواحی گردابه‌ای بزرگتر بهبود پیدا می‌کند. همچنین نتایج نشان داد با افزایش عدد هوادهی و عدد رینولدز پره میزان تجمع گاز در مخزن افزایش پیدا می‌کند. با بررسی عدد توان پره مشاهده شد که با افزایش عدد هوادهی در رینولدز ثابت پره میزان توان مورد نیاز برای اختلاط رفتار کاهشی و در عدد هوادهی ثابت با افزایش عدد رینولدز میزان توان مصرفی افزایش پیدا می‌کند.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

CFD Simulation of Operational Parameters Effects on Mixing Quality of Two-phase Gas-Liquid Flow in Agitated Vessel

نویسنده English

Amir Heidari
Faculty of Chemical, Petroleum and Gas Engineering, Semnan University, Semnan, Iran
چکیده English

In this contribution, behavior of gas phase distribution in a two phase gas-liquid stirred vessel with Rushton turbine was studied by computational fluid dynamic (CFD) technique at different operational conditions. Multiphase flow regime in the in the two phase gas-liquid vessel was modeled by Eulerian-Eulerian multiphase flow approach. Due to complex hydrodynamics and turbulent flow in the agitated vessel, RNG k-ε was used to simulate turbulence flow behavior. With study of operational conditions by means of Aeration and impeller Reynolds dimensionless numbers, distribution of gas phase volume fraction was studied in the vessel. The results showed minimum hold up of the gas phase exists between vessel bottom up to impeller and maximum gas phase hold up is formed in the impeller zone. Also, it was observed due to the formation of larger vortex areas with increase in impeller Reynolds number the mixing quality in the vessel improves. Furthermore, it was shown that increase in Aeration and impeller Reynolds numbers enhances gas phase holdup in the vessel. Study of impeller Power number showed that with increase in Aeration number the amount of mixing power is reduced at constant Reynolds number. Also, it was observed that increase in Reynolds number enhances power consumption at constant Aeration number.

کلیدواژه‌ها English

Two phase stirred vessel
Mixing
CFD Simulation
Rushton impeller
gas phase distribution
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