SEMAN, MOHAMAD TARMIZI ABU (2016) Experimental And Computational Study Of Flow Over A Rotating Cylinder With Surface Roughnes. PhD thesis, Universiti Sains Malaysia.
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Abstract
Dalam tesis ini, kaedah secara eksperimen dan pengkumputeran telah dikaji bagi memahami dan mengetahui bagaimana kesan putaran dan kekasaran permukaan bagi sesuatu silinder yang berpusing disertai dengan aliran angin. Permukaan silinder tersebut telah dibaluti dengan tiga jenis kertas pasir yang berlainan kekasaran. Keseluruhannya, ujikaji tersebut telah dijalankan di dalam terowong angin dengan kelajuan angin antara 0.65m/s sehingga 13.21m/s. Anggaran kekasaran permukaan silinder diukur dengan ketinggian purata (Ra) diantara 5.0μm sehingga 77.0μm dan anggaran kelajuan putaran sehingga 400 putaran per minit. Kajian utama ujikaji ini adalah mengukur penggiraan daya tujah dan daya geseran menggunakan “Light Weight Smart Motor (LWSM)” ketika putaran dua dimensi silinder. Keratan rentas bagi bahagian ujiian di dalam terowong angin adalah 300mm x 300mm. Selain daripada ujian daya tujah dan daya geseran, aliran di sebalik silinder berputar juga diukur dan imej-imej vortices ditangkap semasa uji kaji. Pelbagai jenis data yang dikumpul dengan mengulangi pemerhatian bagi pelbagai nombor Reynolds. Tambahan pula, komputasi dinamik bendalir (CFD) simulasi mengesahkan vortex membentuk dan memberikan petunjuk tempat yang sesuai bagi kedudukan silinder daripada halangan-halangan yang kecil dan mendapatkan imej vortex yang terbaik. Perisian komersial CFD ANSYS FLUENT® adalah perisian untuk mengkaji aliran yang melibatkan putaran dan kekasaran permukaan. Perbandingan dalam simulasi dan ujian eksperimen menunjukkan perbezaan sebanyak 10%. Untuk Re>20000, pusingan mempunyai kesan yang amat kecil keatas daya-daya yang bertindak ke atas aliran sekitar kekasaran permukaan silinder. ________________________________________________________________________________________________________________________ Experimental and computational approaches are taken in this thesis, to understand how rotation and surface roughness affects the dynamics of a cylinder in flow. The roughness was simulated by attaching three types of sandpaper with various roughness, to the cylinder surface. The experiment takes place in a wind tunnel, applying a free stream velocity within the range from 0.65 to 13.21 m/s. The range of average rough cylinder (Ra) is 5.0μm to 77.0μm and the range of rotation speeds of up to 400 rev/m. The study focuses on calculating the lift and the drag forces using a “Light Weight Smart Motor (LWSM)” and a rotating two-dimensional circular cylinder. The cross-section of the test section for the open circuit wind tunnel is 300mm by 300mm. Apart from testing lift and drag forces, the flow behind the rotating cylinder is measured, and images of vortices shedding are captured during experimentation. A wide range of data is gathered by repeating the observations for various Reynolds numbers. Furthermore, Computational Fluid Dynamics (CFD) simulations verify vortex shedding and provide an indication of where to place the experimental device, comprised of small obstacles, to achieve the best suppression of vortex shedding. ANSYS FLUENT® commercial CFD software simulated the flows with respect to rotation and surface roughness. A comparison of the simulation and the experimental results shows close agreement, with approximately 10% variation. For Re > 20000, the rotation has an extremely small effect on the overall forces acting on the flow field around the cylinder with surface roughness.
| Item Type: | Thesis (PhD) |
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| Additional Information: | Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=2810 |
| Subjects: | T Technology T Technology > TJ Mechanical engineering and machinery > TJ1-1570 Mechanical engineering and machinery |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Mekanikal (School of Mechanical Engineering) > Thesis |
| Depositing User: | Mr Mohd Jasnizam Mohd Salleh |
| Date Deposited: | 12 Jul 2018 06:40 |
| Last Modified: | 15 Aug 2018 04:40 |
| URI: | http://eprints.usm.my/id/eprint/41002 |
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