تحلیل عددی دریفتر لاگرانژی نوع SVP و بررسی تاثیرات مشخصه‌های هندسی بر عملکرد آن

نوع مقاله : مقاله پژوهشی

نویسندگان

1 مجتمع دانشگاهی هوادریا، دانشگاه صنعتی مالک اشتر

2 دانشگاه صنعتی شیراز، دانشکده مهندسی مکانیک و هوافضا

چکیده

در این مقاله به‌منظور بررسی تأثیر ویژگی‌های هندسی یک دریفتر لاگرانژی بر عملکرد آن در شرایط جریان در خلیج‌فارس، انواع دریفترهای SVP با استفاده از محیط محاسباتی سه‌بعدی تجزیه‌وتحلیل شده‌اند. با مشاهده و بررسی شکل جریان در اطراف حفره‌های جانبی و داخلی دراگو مشخص شد که وجود حفره روی دراگو باعث توزیع یکنواخت نیروهای فشاری و لزجت در سطح دراگو می‌شود. اگر از سیلندر بدون حفره به‌عنوان دراگو استفاده شود، به‌خصوص در جریان‌های با سرعت‌بالا، شاهد کاهش قابل‌توجهی در ضریب پسا و لغزش خواهیم بود.  افزایش تعداد حفره­ ها بر روی دراگو تأثیر چندانی در عملکرد دریفتر نخواهد داشت و مؤثرترین عامل تغییرات قطر و ارتفاع دراگو هستند. به‌گونه‌ای که افزایش 30 درصدی قطر دراگو سبب افزایش 90 درصدی ضریب پسا می­شود. به‌طورکلی با بررسی کانتور و بردار سرعت جریان مشخص شد که طراحی هندسه دراگو دریفتر باید به‌صورتی باشد که در پشت دراگو گردابه­ های چرخشی جریان با شعاع کوچک‌تر شکل گیرد و این گردابه­های کوچک سبب توزیع یکنواخت نیروهای هیدرودینامیکی در سطح دراگو و جلوگیری از لغزش دریفتر در تغییرات سرعت ناگهانی جریان­ ها می­شوند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical simulation of the lagrangian SVP drifter and investing the effect of the geometry’s characteristic on its performance

نویسندگان [English]

  • Nader Kharestani 1
  • Milad Peymani 2
  • Mohammad Reza Khalilabadi 1
1 Faculty of Naval Aviation, Malek Ashtar University of Technology
2 Shiraz University of Technology, Department of Mechanical and Aerospace Engineering
چکیده [English]

In this paper, different types of SVP drifters are analyzed by using a three-dimensional computational environment to investigate the effect of geometrical characteristics of a Lagrangian drifter on its performance in the flow conditions in the Persian Gulf. By observing and examining the shape of the flow around the lateral and internal cavities of the Drago, it is concluded that the presence of cavities on the Drago causes a uniform distribution of compressive and viscous forces on the surface of the Drago. If a holeless cylinder is used as a Drago, a significant reduction in drag and slip coefficient is seen, especially at high-velocity currents. Increasing the number of holes on the Drago will not have much effect on the drifter performance and the most effective factors are changing the diameter and height of the Drago. Thus, a 30% increase in the diameter of the Drago increases the drag coefficient by 90%. In general, by examining the contour and flow velocity vector, it is found that the geometry design of Drago Drifter should be such that behind the drag, the smaller radius flow vortices are formed, and these small vortices cause uniform distribution of hydrodynamic forces on the surface of the Drago and prevent the drifter from slipping in sudden changes in current velocity.

کلیدواژه‌ها [English]

  • lagrangian drifter
  • Drag coefficient
  • SVP drifter
  • holey-sock drogue
  • hydrodynamic force
  • flow vortices
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