مطالعه عددی ارتعاش القایی گردابه برای سیلندر دایره ای

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی مکانیک، دانشگاه خلیج فارس، بوشهر، ایران

چکیده

در ارتعاش القایی گردابه، سازه با جریان سیال تأثیر متقابل دارد که منجر به ارتعاش سازه شده و در شرایطی موجب تخریب سازه می‌شود. در این مقاله، اثر ارتعاش القا شده بر تک سیلندر و دو سیلندر در حالت‌های چرخان و غیر چرخان به صورت عددی مورد مطالعه قرار گرفته است. در حالت تک استوانه غیرچرخان نتایج نشان داد سرعت کاهنده و ضریب میراکننده تأثیر قابل توجهی بر اختلاف فاز بین مؤلفه‌های مختلف نیروی وارده بر سیلندر، شکل گردابه‌های تشکیل شده، الگوی ریزش آنها و ارتعاش سیلندر دارند. افزایش ضریب میرایی باعث کاهش ارتعاشات سیلندر می‌شود. الگوی ریزش گردابه برای همه سرعت‌های کاهنده و ضرایب میرایی مورد بررسی به صورت 2S است. در بین موارد بررسی شده، دو نوع الگوی ارتعاشی هارمونیک کامل و ضربه مشاهده شد. بیشترین دامنه ارتعاش سیلندر مربوط به سرعت کاهنده 4 در ς=0 بوده و کمترین جابه جایی سیلندر مربوط به سرعت کاهنده 3 است. در حالت استوانه‌های چرخان مشاهده گردید که چرخش سیلندر آرایش ریزش گردابه‌های پشت سیلندر را تغییر می‌دهد و قدرت آ نها را کاهش می‌دهد و این امر، باعث کاهش محسوس نوسانات ضریب برآ و در نتیجه کاهش شدید ارتعاش سیلندرها می‌شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical Study on the Vortex-induced Vibration of Circular Cylinder

نویسندگان [English]

  • E. Izadpanah
  • Y. Amini
  • A. Ashouri
Department of Mechanical Engineering, Faculty of Engineering, Persian Gulf University, Bushehr, Iran
چکیده [English]

In the vortex-induced vibration the structure interacts with the fluid flow that results in the vibration of the structure and sometimes leads to the destruction of it. In this paper, the effect of the vortex-induced vibration on one and two cylinder(s) in the rotating and non-rotating states are studied, numerically. For the case of single non-rotating cylinder, the effect of the reduced velocity and damping ratio on the displacement and velocity of circular cylinder and also on the lift coefficient and its components are investigated. The cylinder displacement decreases by increasing the damping ratio. The vortex shedding pattern for all examined reduced velocity and damping ratio is in the 2S mode. In all cases, two patterns of vibration, harmonic and beating phenomena, can be observed. The maximum value of the vibration amplitude is related to the reduced velocity of 4 for ζ= 0 and the minimum is belonged to the reduced velocity of 3. For the case of rotating cylinder, it is observed that the rotation of cylinder(s) affects the vortex shedding pattern and their strength, significantly. Therefore, the fluctuation of lift coefficient and vibration of cylinder(s) are reduced considerably.

کلیدواژه‌ها [English]

  • Vortex-induced vibration
  • vortex shedding
  • Beating phenomenon
  • circular cylinder
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