مطالعه آزمایشگاهی جریان هوا در شفت ریزشی گردابی با استفاده از روش فاکتوریل کامل

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای سازه‌های هیدرولیکی، بخش مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه شهید باهنر کرمان، کرمان، ایران

2 استاد، بخش مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه شهید باهنر کرمان، کرمان، ایران

10.22093/wwj.2019.190172.2886

چکیده

شفت‌ ریزشی گردابی (سازه ورتکس) در سیستم‌های جمع‌آوری فاضلاب و زهکشی شهری به‌منظور انتقال سیال از مجاری سطحی به تونل‌های زیرزمینی عمیق به‌کار می‌رود. در طول ریزش، مقدار زیادی هوا به داخل آب نفوذ می‌کند و در پایین‌دست شفت ریزشی آزاد می‌شود. در این پژوهش، با ساخت مدل فیزیکی سازه از قطعات پلکسی‌گلاس، جریان هوا در سازه مطالعه شد. با استفاده از آنالیز ابعادی نشان داده شد که عدد فرود جریان (Fr)، نسبت ارتفاع کل ریزش به قطر شفت (L/D) و نسبت عمق چاهک به قطر شفت (Hs/D)، عوامل مؤثر بر دبی نسبی هوا (b=Qa/Q) در سازه هستند. دقت و توانایی روش فاکتوریل کامل برای توصیف عملکرد سازه در میزان هوای خروجی از آن با استفاده از داده‌های آزمایشگاهی تأیید شد. نتایج نشان داد که دبی نسبی هوا در سازه بین 048/0 تا 278/0 تغییر می‌کند و با افزایش عواملFr ، L/D و Hs/D افزایش می‌یابد. همچنین با توجه به این که بیشترین سرعت خروج هوا از سازه مربوط به لوله‌های هواگیری (با قطر یکسان Da) است که در فاصله بین Da4 تا Da9 از محور شفت قائم قرار دارند، لذا محل مناسب استقرار مجرای هواگیری برای سازه در این محدوده تعیین شد. علاوه بر این معادله‌ای غیر خطی به‌ صورت تابعی از Fr، L/D و Hs/D برای تخمین دبی نسبی هوا در سازه ورتکس با استفاده از آنالیز رگرسیون ارائه شد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental Study of Air Flow in a Vortex Structure Using Full Factorial Method

نویسندگان [English]

  • Mohammad Mahmoudi Rad 1
  • Mohammad Javad Khanjani 2
1 PhD Candidate, Dept. of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
2 Prof., Dept. of Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
چکیده [English]

Vortex drop shaft (Vortex structure) is used in sewage and drainage systems to transfer fluid from surface conduit to deep underground tunnels. During the plunge, large volume of air is entrained into the water and then released of the drop shaft downstream. In the current research, an experimental model, made of Plexiglas segments, was set up to investigate hydraulic performance of vortex structure. Dimensional analysis results illustrated that ratio of sump depth to shaft diameter (Hs/D), ratio of drop total height to shaft diameter (L/D), and Froude number (Fr) were considered effective variables on relative air discharge (β=Qa/Q). The ability of the full factorial method (FFM), to describe this structure’s hydraulic characteristics, was validated using experimental data. The results indicated that the relative air discharge changed from 0.048 to 0.278 and increased with an increase in Fr, L/D and Hs/D factors. With respect to the maximum velocity of air outflow from the structure of the air vent pipes (with the same diameter Da), located between the 4Da and 9Da from the axis of the vertical shaft, this range is recommended for installation of air vent pipes. Furthermore, a regression-based-equation in the form of a quadratic polynomial as a function of Hs/D, L/D and Fr was proposed to estimate relative air discharge (β).

کلیدواژه‌ها [English]

  • Vortex Structure
  • Relative Air Discharge
  • Full Factorial Method
  • regression analysis
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