碩士 / 國立臺灣海洋大學 / 系統工程暨造船學系 / 104 / It is time consuming and complicated to simulate the propeller and current
turbine performances by viscous flow RANS method. The objective of this thesis is to
develop an efficient and applicable method for the computations of propeller and
current turbine performance, and later can be extended to the cases of large angles of
attack. The blade element momentum theory (BEMT) is selected as the method in this
thesis. The BEMT has been developed for some time, and it is widely used to the
evaluation of wind turbine performance. The BEMT is seldom used in evaluating
marine propeller performance, and one of the reason is that they usually have stronger
three-dimensional effects due to larger area ratios. Also it is not easy to find a
complete database of the lift and drag coefficients of two dimensional foils used on
propellers. In this thesis, we have first derived formulations of BEMT for both marine
propellers and current turbines, and we then spent a lot of time to establish a lift and
drag database for modified NACA66 and a=0.8 mean-line sections by using RANS
method. The difficulties of establishing this database are first the variations of
thickness and camber ratio on propeller and current turbine geometries, and secondly
the accurate computations of forces at larger angles of attack. The accuracy of this
database directly determine the accuracy of BEMT. In order to understand and
investigate the accuracy of our database and BEMT, we have applied the BEMT to the
computations of 10 different propeller geometries, and the BEMT results are
compared to experimental data. “Correction factors” are defined for both the lift and
drag forces, and it is found that the correction factors of the lift are mostly 1 for these
10 propellers, which means the lift coefficients are computed quite accurately. On the
other hand, it is not true for drag coefficient computations. The accuracy of drag
coefficients has to be improved. It is also found that the BEMT is sensitive to the
single blade area ratio, and it is not accurate for propellers with large single blade area
ratios. Finally, we have applied BEMT to the computations of current turbine, and
similar conclusions are obtained as for the marine propellers. The presented BEMT is
feasible for marine propellers and current turbine in forward conditions; however,
more efforts are necessary for improving the database accuracies, especially at large
angles of attack.
| Identifer | oai:union.ndltd.org:TW/104NTOU5345028 |
| Date | January 2016 |
| Creators | Jian, Xiu-Ting, 簡秀庭 |
| Contributors | Hsin, Ching-Yeh, 辛敬業 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 79 |
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