Authors:M. Zheng, L. Zhang, H. P. Teng, J. Hu, and M. L. Hu
In the present paper, CFD simulation is used to perform the numerical calculation of behaviours of multi-blade drag typed VAWT. The sliding grid technology, FLUENT software and PISO algorithm are involved. By taking wind power efficiency Cp as the goal function, the optimal situations of multi-blade drag typed VAWT with 4 and 6 blades are conducted by CFD simulation. In this investigation, the variable parameters include the rotation rate of wind-mill ω, the blade installation angle θ and the blade width d. The results show that: the optimal working conditions for the 4-blade wind mill at the inlet wind speed 8 m/s are ω = 18 r/ min, θ = 28°, and d = 0.83 m, which induces an optimal wind power efficiency rate Cp = 27.127%; the optimal working conditions for the 6-blade wind mill at the inlet wind speed 8 m/s are ω = 18 r/min, θ = 27°, and d = 0.67 m, which leads to an optimal wind power efficiency rate Cp = 30.404%.
In the present paper, various formulae for evaluating critical buckling strain of bending pipeline are analyzed on basis of its actual nature, available test data or finite element calculation results. The available test data is from different resources, it provides a more objective comparison; Especially, the experimental bending buckling data of Corona et al. and Kyriakides et al. for Al-6061-T6 aluminum pipes with various D/t value, as well as the prediction of Minnaar’s FEM regressive formula for high grade steel pipe are reanalyzed to check the reasonability of the plastically elliptical cross-section model. It shows that the consequence of the plastically elliptical cross-section model is more reasonable than others for the critical buckling strain prediction of a pipe bending in most cases.