No abstract

Airfoil geometric configuration is very important for aerodynamic performance of a straight-bladed vertical axis wind turbine (SB-VAWT). In recent study, Islam et al have pointed out old NACA-4 are not perfectly suited for SB-VAWT operating at low Reynolds number and special purpose airfoils is needed. Islam has singled out four required geometric features which would be suitable for SB-VAWT airfoil. However, the maximum thickness position, considered one of the important geometric parameters, was not involved in Islam's research. In this paper, NACA0015 airfoil was chosen as the basic airfoil, whose maximum thickness position was shifted to generate another four airfoils. With the approach of combining XFLR5 program and Viterna-Corrignan psot-stall mode, airfoil characteristics in attack angle range from 0 degree to 90 degree have been calculated. It has been found in this paper that, with the Reynolds number changing from 50,000 to 500,000, altering the maximum thickness position has varying degrees of affects on airfoil aerodynamic characteristics. The maximum thickness position should be involved in the SB-VAWT airfoil design, and the optimum maximum thickness position needs to be determined with the consideration of the Reynolds number range where the SB-VAWT operates.

Cooling system is important in the quality and the efficiency of forming plastic parts. The heat transfer model for conformal chimney cavity and straight pipe cooling system was developed employing thermal analysis module of UG software. The temperature field distributions of two cavities were analyzed. The differences in chimney forming warping deformations, shrinkage and freeze times for the two types of cooling systems were analyzed quantitatively by Moldflow software. The results showed that the temperature field distribution of the conformal cooling system was more homogeneous and the forming quality and efficiency of molding for the plastic parts was better. Finally, the cooling system parameters were optimized through orthogonal test and range analysis method.

A new airfoil design method for H type vertical axis wind turbine is introduced in the present study. A novel indicator is defined to evaluate vertical axis wind turbine aerodynamic performance at variable tip speed ratios and selected as the airfoil design objective. A mathematic model describing the relationship between airfoil design variables and objective is presented for direct airfoil design on the basis of regression design theory. The aerodynamic performance simulation is conducted by computational fluid dynamics approach validated by a wind tunnel test in the study. Based on the newly developed mathematic model, a new airfoil is designed for a given wind turbine model under constant wind speed of 8 m/s. Meanwhile, the comparison of aerodynamic performance for newly designed airfoil and existing vertical axis wind turbine airfoils is studied. It has been demonstrated that, by the novel indicator, the rotor aerodynamic performance at variable tip speed ratios with the newly designed airfoil is 6.78% higher than the one with NACA0015 which is the airfoil widely used in commercial H type vertical axis wind turbine.

In order to try to reduce the influence of weld mark on the appearance quality and mechanical properties of plastic products, with the combination of injection molding simulation software and the orthogonal test design, reasonable test analysis programs was designed. Products weld mark depth was the evaluation index, and get the optimal parameter combination which could control the quality of the weld, then the results was verified by molding simulation. The results show that through the optimization of process parameters combination, the weld quality was improved and the negative impact on plastic parts was reduced.