کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7175846 1466571 2018 17 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Flow-induced vibration of three unevenly spaced in-line cylinders in cross-flow
ترجمه فارسی عنوان
لرزش ناشی از جریان از سه سیلندر خطی درون خطی که به صورت ناهموار فاصله دارند، در جریان متقابل است
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی مکانیک
چکیده انگلیسی
The flow over three cylinders arranged in-line with uneven spacing in cross-flow is numerically investigated at a Reynolds number of 200. The center-to-center distance between the upstream and the most downstream cylinder was kept constant at 4 diameters. The distance between the inline centers of the upstream and middle cylinders (x) was studied in the range of 1.05 to 2.95 diameters. The flow structure around the cylinders shows two distinctive patterns of vortex shedding, one of which occurs at x=1.60 and 1.80 diameters, and causes significantly higher oscillating lift and mean drag forces with a lower value of Strouhal number. At these middle cylinder locations, the shear layer reattaches on the downstream cylinder and results in vortex formation in the gap between the middle and downstream cylinders. On the other hand, at all other locations of the middle cylinder the shear layer does not reattach on the downstream cylinder. Moreover, when the middle cylinder is located at x=1.60 or 1.80 diameters, the vortex formation length is shorter and the vorticity in the downstream vortex street is higher than the case when the middle cylinder is located at all other locations. To understand the effect of these distinctive flow features on the flow-induced vibration response of the most downstream cylinder, the coupling between the flow field and the cylinder motion is numerically modeled. As the reduced velocity is increased, the oscillation amplitude of the downstream cylinder increases to its maximum at lock-in, then it starts to decrease similar to the case of a single cylinder. However, the oscillation amplitude reaches a higher value than that observed for the case of vortex-induced vibration of both a single cylinder and two tandem cylinders. Moreover, significant oscillation amplitude is pertained at high reduced velocities with dependency on the uneven spacing between the cylinders. The frequency of oscillations increases at different rates in three different ranges of reduced velocities, indicating different energy transfer mechanisms. Although the frequency of vibration is shifted away from the structure resonance frequency at high reduced velocities, the significant amplitude of oscillations is attributed to the interaction of two opposing mechanisms that occur when the cylinder is at different positions in the cycle. The wide range of reduced velocities at which the cylinder vibrates with a significant amplitude makes the configuration of three in-line cylinders a good candidate for flow energy harvesting.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Fluids and Structures - Volume 76, January 2018, Pages 367-383
نویسندگان
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