تأثیر فاصله بر توان مهار شده حاصل از نوسانات دو سیلندر با آرایش پشت سرهم

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش آموخته دکتری سازه‌های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز.

2 استاد گروه سازه‌های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز

3 استادیار گروه سازه‌های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز.

4 استاد گروه معماری دریایی و مهندسی دریا، دانشکده مهندسی دانشگاه میشیگان.

چکیده

در این مقاله اثر فاصله ­ی دو سیلندر زبر دایره­ ای پشت سر هم بر حرکت ناشی از جریان  بررسی شده است. حرکت ناشی از جریان، پدیده ­ی است که در سازه­ های مختلف در جریان ­های پایدار مانند مبدل ­های حرارتی، پل ­ها، ساختمان ­ها و سازه ­های دریایی رخ می ­دهد.  ارتعاش ناشی از گردابه­ ها و گالوپینگ رایج­ترین پدیده ­­­ها در حرکت ناشی از جریان هستند که در دستگاه مبدل گردابه به ­دلیل اثر متقابل لایه­ی برشی و کفاب سیلندر بالادست رخ می ­دهد. برای نیل به این هدف، توان مهار شده برای سیلندر بالادست، پایین ­دست و مجموع انرژی استخراج گردیده است. معمولاً با افزایش سرعت مقدار توان مهار شده در منطقه­ ی گالوپینگ افزایش می­ یابد، اما برخلاف انتظار در محدوده­ ی سرعت ­های بین 3.1<U<9.0 متر در ثانیه، یک افت یا یک پرش ناگهانی درمقدار توان مهار شده دیده می­ شود. هدف این مقاله، یافتن دلیل حضور این تغییرات و ارتباط آن با فاصله ­ی بین دو سیلندر می ­باشد. نتایج نشان می ­دهد، افزایش فاصله ­ی دو سیلندر بر الگوی جریان بین دو سیلندر و درنتیجه افت­ ها و پرش­ ها موثر است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of distance in flow induced vibration on power conversion caused by the oscillations of two tandem cylinders

نویسندگان [English]

  • Vida Atashi 1
  • Mehdi Ghomeshi 2
  • Seyed Mohsen Sajjadi 3
  • Michael Bernitsas 4
1 Ph.D. in water structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz,Iran.
2 Professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz,Iran
3 Assistant Professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz,Iran
4 Professor, Naval Architecture and Marine Engineering Faculty, University of Michigan, Ann Arbor, Michigan, USA.
چکیده [English]

Flow-induced vibrations (FIVs) are a type of vibration that is caused by the interaction of a structure with a fluid flow. FIVs can occur in a variety of structures, including bridges, buildings, and offshore structures. In the case of tandem cylinders, FIVs can be caused by the interaction of the two cylinders with the fluid flow.
FIVs are suppressed because of their destructive nature. MRElab managed to convert the kinetic energy of water flows into electricity by enhancing FIV (Bernitsas, 2016; Bernitsas et al., 2008). In MRElab, Flow Induced Vibrations (FIV) are studied to convert marine hydrokinetic energy, from oceans, tidal and rivers to electricity using the VIVACE energy harvester. Vortex Induced Vibrations for Aquatic Clean Energy Converter is probably the closest to commercialization because it has suffered extensive laboratory testing and many field deployments since its introduction in 2006. The objective of the Marine Renewable Energy Lab (MRELab) is to investigate FIV of single and multiple cylinders and find different ways to enhance FIV to design VIVACE Converters and optimize the power output for various flow velocities. Vortex-induced vibration (VIV) to a cylinder has been studied experimentally (Alam et al., 2003; Park, 2012) and numerically  (Ding et al., 2013; Kim et al., 2021) by researchers in order to eliminate or at least regulate this unsteady fluid-structure interaction phenomenon since it has been identified as the cause for many structural failures. But it is challenging, and it is still being debated due to the complexity of the interaction between body dynamics and fluid dynamics. The two cylinders arrangement has been studied in many types of research as the simplest arrangement. In this research, both cylinders can oscillate which has not been done very often in previous papers up to now. Moreover, most of the previous experiments on VIV were conducted in TrSL2 regime which fluctuating lift coefficient rises as the Re increases. But in this research, experiments placed in TrSL3 that shear layer becomes fully turbulent, and the fluctuating lift coefficient of a smooth cylinder reaches its maximum value.

کلیدواژه‌ها [English]

  • Vortex Induced Vibrations
  • galloping instability
  • harnessed power
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