مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

شبیه‌سازی عددی مجرا دوبعدی با برآمدگی کف: مقایسه سطح منحنی با سطح مثلثی

نویسندگان
دانشگاه علم و صنعت، تهران
چکیده
در این پژوهش، یک بررسی عددی جامع از جریان سیال تراکم‌پذیر در یک مجرا دوبعدی با برآمدگی‌هایی به شکل منحنی و مثلثی در کف مجرا، تحت شرایط جریان زیرصوتی و فراصوتی انجام شده است. برای تولید هندسه و شبکه از نرم‌افزار گمبیت و برای حل عددی جریان از نرم‌افزار فلوئنت استفاده گردید. مدل آشفتگی k-ω SST به همراه حل‌گر ضمنی مبتنی بر چگالی برای شبیه‌سازی جریان در اعداد ماخ ورودی 0.5، 0.675 و 1.4 به کار گرفته شد. نتایج به‌دست‌آمده نشان‌دهنده‌ی تغییرات مشخص فشار و عدد ماخ در طول مجرا بوده که این تغییرات به‌طور مستقیم تحت تأثیر هندسه برآمدگی و رژیم جریان قرار دارد. در عدد ماخ 0.5، فشار در لبه ابتدایی برآمدگی منحنی تا 1.2 برابر فشار ورودی افزایش یافت و عدد ماخ تا 0.43 کاهش پیدا کرد. در ماخ 0.675، فشار تا 1.4 برابر افزایش یافت و عدد ماخ به 0.6 کاهش یافت. در حالت جریان فراصوتی (ماخ 1.4)، تشکیل موج شوک به وضوح مشاهده شد که با کاهش فشار تا 0.75 برابر و افزایش عدد ماخ تا 1.5 در پایین‌دست همراه بود. برآمدگی‌های مثلثی نسبت به منحنی، اغتشاشات قوی‌تری در مشخصات جریان ایجاد کردند و منجر به شکل‌گیری شوک‌ها و گرادیان‌های فشاری شدیدتری شدند. بردارهای سرعت و خطوط جریان، تمرکز شوک‌ها در نزدیکی برآمدگی را نشان دادند. یافته‌های این پژوهش برای بهینه‌سازی عملکرد آیرودینامیکی در سامانه‌های مهندسی نظیر توربوماشین‌ها، نازل‌ها و مجاری انتقال سیال اهمیت بالایی دارند و تأثیر هندسه بر پدیده‌هایی نظیر شکل‌گیری شوک، اتلاف انرژی و بازیابی فشار را به‌خوبی نشان می‌دهند
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Numerical Simulation of a Two-Dimensional Channel with a Raised Bottom: Comparison of a Curved Surface with a Sharp Surface

نویسندگان English

Amirhossein Barzigar
Erfan Ebadati
Seyed Mostafa Hosseinalipoor
Mechanical Engineering Department, Iran University of Science and Technology (IUST), Tehran, Iran
چکیده English

This study presents a comprehensive numerical investigation of compressible fluid flow in a two-dimensional channel featuring curved and triangular protrusions on the channel floor, under subsonic and supersonic flow conditions. Geometry and mesh generation were carried out using Gambit, while numerical simulations were performed using Fluent. The k-ω SST turbulence model, along with a density-based implicit solver, was employed to simulate the flow at inlet Mach numbers of 0.5, 0.675, and 1.4. The results revealed significant variations in pressure and Mach number along the channel, directly influenced by the protrusion geometry and flow regime. At Mach 0.5, the pressure at the leading edge of the curved protrusion increased up to 1.2 times the inlet pressure, while the Mach number dropped to 0.43. At Mach 0.675, the pressure rose to 1.4 times the inlet value, with the Mach number decreasing to 0.6. Under supersonic conditions (Mach 1.4), shock wave formation was clearly observed, accompanied by a pressure drop to 0.75 and an increase in Mach number to 1.5 downstream. Triangular protrusions induced stronger disturbances in flow characteristics compared to curved ones, leading to the formation of more intense shocks and steeper pressure gradients. Velocity vectors and streamlines indicated shock concentration near the protrusions. The k-ω SST model effectively captured these behaviors. The findings are significant for optimizing aerodynamic performance in engineering systems such as turbomachinery, nozzles, and fluid transport ducts, highlighting the influence of geometry on phenomena such as shock formation, energy loss, and pressure recovery

کلیدواژه‌ها English

Flow Shock
Supersonic Flow
Protrusion
Pressure Gradient
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