بررسی عددی تأثیر هندسه لبه پله بر رفتار هیدرودینامیکی جریان در سرریزهای پلکانی با استفاده از FLOW-3D

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه بیرجند، بیرجند، ایران.

2 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه بیرجند، بیرجند، ایران

10.22034/nawee.2026.579642.1211
چکیده
هدف: هدف این پژوهش، بررسی عددی تأثیر سه هندسه مختلف لبه پله ساده، مدور و مشبک بر رفتار هیدرودینامیکی جریان و میزان استهلاک انرژی در یک سرریز پلکانی با ده پله است. به‌علاوه برای ارزیابی استهلاک انرژی، پروفیل‌های سرعت و نوسانات فشارِ مرتبط با هر طراحی لبه انجام شده است تا هندسه بهینه برای پایداری جریان شناسایی شود.
مواد و روش‌ها: از شبیه‌سازی عددی سه‌بعدی در نرم‌افزار FLOW-3D با استفاده از روش حجم سیال (VOF) و مدل آشفتگی (RNG) k-ε بهره گرفته شد. شبیه‌سازی‌ها برای دبی 09/0 مترمکعب بر ثانیه انجام و نتایج با داده‌های آزمایشگاهی اعتبارسنجی گردید که میانگین خطای مطلق (MAPE) بین ۵ تا ۸ درصد را نشان داد.
نتایج: سرریز لبه‌دار مشبک با کاهش ۱۵ تا ۲۰ درصدی سرعت جریان نسبت به لبه ساده، بیشترین استهلاک انرژی را ایجاد می‌کند. با وجود اینکه میزان فشار مثبت در وجه افقی پله‌های لبه‌دار مشبک نسبت به سرریز پلکانی لبه‌دار ساده 4/16 درصد افزایش یافته است ولی سرریزهای دارای لبه ساده و مدور رفتار پایدارتری در برابر فشارهای منفی در وجه قائم پله‌ها از خود نشان می‌دهند و برای شرایطی که پایداری جریان و جلوگیری از خستگی سازه یا خطر پدیده کاویتاسیون در اولویت است، گزینه‌های ایمن‌تری محسوب می‌شوند.
نتیجه‌گیری: گرچه سرریز لبه‌مشبک بالاترین نرخ استهلاک انرژی را دارد، به دلیل ایجاد نوسانات شدید که ریسک کاویتاسیون و خستگی سازه را افزایش می‌دهد گزینه مطلوبی نیست. سرریز پلکانی لبه ساده به دلیل عملکرد هیدرودینامیکی مناسب، پایداری جریان، سادگی ساخت و هزینه کمتر به عنوان گزینه عملی بهینه پیشنهاد می‌شود.

کلیدواژه‌ها


عنوان مقاله English

Numerical Investigation of Step Edge Geometry Effects on Hydrodynamic Flow Behavior in Stepped Spillways Using FLOW-3D

نویسندگان English

Elham Karimzadeh 1
Mahdi Mollazadeh 2
1 Department of Civil Engineering, Faculty of Engineering, Birjand University, Birjand, Iran.
2 Department of civil engineering, Faculty of Engineering, University of Birjand, Birjand, Iran.
چکیده English

Objective: This study aims to numerically examine the effect of three different step edge shapes: plain, grated, and circular types, on the complex hydrodynamic characteristics of flow over a ten-step spillway. It also seeks to assess energy dissipation, velocity distribution, and pressure variations for each configuration to determine the most suitable geometry for stable flow conditions.
Methods: Three-dimensional numerical simulations were carried out using FLOW-3D. The Volume of Fluid method along with the RNG turbulence model was applied. Simulations were performed at a constant discharge of 0.09 m³/s. The numerical outcomes were compared with reliable experimental data for validation. The comparison showed good agreement, with an average relative error ranging from 5% to 8%.
Results: The meshed-edge spillway creates the highest energy dissipation by reducing the flow velocity by 15 to 20 percent compared to the simple edge. Although the positive pressure on the horizontal face of the meshed-edge steps increased by 16.4% compared to the simple-edge spillway, spillways with simple and circular edges exhibit more stable behavior against negative pressures on the vertical faces of the steps. Therefore, they are safer options for conditions where flow stability and the prevention of structural fatigue or cavitation risk are priorities.
Conclusions: Despite its higher energy dissipation capacity, the grated edge is not recommended because it generates strong fluctuations that increase the likelihood of cavitation and structural damage. The plain edge is suggested as the best practical option due to its acceptable hydraulic performance, flow stability, simpler construction, and lower cost.

کلیدواژه‌ها English

Stepped spillway
FLOW-3D
RNG model
Energy dissipation
Step edge geometry
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