This study is a structural analysis of slewing bearings for wind turbines. The ball of a bearing delivers load while making contact with raceways of the inner and outer rings. To facilitate stress analysis of the slewing bearing, which has more balls than other types of bearing, the balls were converted into spring elements. Considering the shape of contact between balls and raceways, one, two, and three spring elements were introduced. Global finite element analysis of the bearing, with balls as spring elements, showed that the bearing experienced different degrees of deformation depending on the number of springs. Using the bearing deformation obtained from the global analysis, cut boundary constraint was applied for local contact analysis of balls and raceways. The contact stress between balls and raceways showed that more uniform stress could be achieved by increasing the number of springs.

The objective of this paper is to suggest a new method of a wind turbine performance test. The performance test of a wind turbine is generally carried out in a wind tunnel. The test needs not only a high-accuracy measuring system but also durable structure to withstand high speed turbine rotation and wind flow. Therefore, we tried turbine performance test using a towing tank to improve stability and reliability. Because a turbine rotates more slowly and generates more torque in the water than in the wind tunnel under similarity conditions. In this study, we developed turbine performance test systems and verified the turbine test method using a towing tank through comparing results of the wind tunnel and the towing tank test. (접수일 2011. 9. 7, 수정일 2011. 12. 15, 게재확정일 2011. 12. 19) * 현대중공업 선박해양연구소 ■ E-mail : kangjm@hhi.co.kr ■ Tel : (052) Key words Wind turbine(풍력터빈), Performance test(성능 시험), Model test(모형 시험), Wind tunnel(풍동), Towing Tank(예인수조)