بررسی پارامترهای آشفتگی در پرش هیدرولیکی با مقاطع مستطیلی واگرا با استفاده از مدل Fluent

نوع مقاله: مقاله پژوهشی

نویسنده

استادیار گروه مهندسی آب دانشگاه محقق اردبیلی

چکیده

حوضچه ­های آرامش با مقطع واگرا دارای عملکرد هیدرولیکی مناسب­تر و هزینه ساخت کمتر نسبت به حوضچه­ های کلاسیک می­باشند. در تحقیق حاضر با به­ کارگیری داده­ های آزمایشگاهی و به ازای هفت عدد فرود مختلف در محدوده 1/9-2/3، سه مدل از حوضچه ­های مذکور با هندسه ­های مختلف از نظر زاویه واگرایی و نوع دیواره، در حالت سه بعدی مورد شبیه سازی عددی قرار گرفت. برای تحلیل آشفتگی از مدل­های k-ε RNG و RSM و برای سطح آزاد جریان از مدل حجم سیال (VOF) در محیط نرم­افزار Fluent استفاده شد. دقت مدل­های آشفتگی مذکور در شبیه سازی سطح آزاد پرش مشابه یکدیگر و میانگین خطای محاسباتی آنها به ­ترتیب 4/7 و 7/5 درصد حاصل شد. اما در شبیه سازی پروفیل­های سرعت مدل RSM عملکرد بهتری را به همراه داشت، به­ طوری­ که میانگین خطای محاسباتی مدل­ های k-ε RNG و RSM به­ ترتیب 2/16 و 7/7 درصد بدست آمد. بر اساس نتایج مدل عددی وقوع جریان دوپایا در مقاطع واگرا به­ خوبی قابل مشاهده بود. همچنین با استفاده از مدل RSM توزیع قائم شدت آشفتگی، تنش­های رینولدز و انرژی جنبشی اغتشاش در مقاطع مختلف پرش مورد بررسی قرار گرفت.
 

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Hydraulic Jump Turbulence Parameters in Divergent Rectangular Sections using Fluent Model

نویسنده [English]

  • Mohammad Reza Nikpour
Assistant Professor, Department of Water Engineering, University of Mohaghegh Ardabili.
چکیده [English]

A Stilling basin with divergent section has better performance and lower constructional costs than the classic basin. It can easily adapt itself to the upstream and downstream conditions in terms of depths and cross sections (Omid et al., 2007). Khalifa and McCorquodale (1979) studied radial hydraulic jumps in a gradually expanding channel of rectangular cross section and developed a theoretical equation assuming a second degree polynomial for the surface profile. Omid et al. (2007) studied the hydraulic jump formed in a gradually expanding stilling basin of trapezoidal cross section. They also investigated the hydraulic jumps for three different basin side slopes. Their experimental results indicated that the divergence of the basin for a given side slope causes reductions in the sequent depth and jump length, and an increase of the energy loss in  jump relative to those observed in rectangular cross sections. Sahebi (2013) simulated a divergent hydraulic jump in rectangular basins using standard and RNG turbulence models. The outputs of the numerical model showed that the standard turbulence model evaluated the free surface of flow, jump length and maximum velocity in defined sections better than RNG turbulence model. In this study, for seven Froude numbers in the range of 3.2-9.1, three models of the divergent basins were numerically simulated at three dimensional conditions with various geometries of divergence angle and wall type. The k-ε RNG and RSM models were used for turbulence analysis and volume of fluid (VOF) model was used for simulating of free surface profile in the Fluent model. Also, vertical distributions of turbulence intensity, Reynolds stresses and turbulent kinetic energy were investigated using the RSM model in various sections of the hydraulic jumps.

کلیدواژه‌ها [English]

  • Bistable flow
  • Divergent section
  • Hydraulic jump
  • Stilling basin
  • Turbulence model
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