The deteriorating effects of greenhouse gases resulting from the use of fossil fuels have led to increased public attention to renewable energy sources, with wind energy being a particularly favored option. This prompted the development of various wind turbine types' efficiency. This study intends to explore the influence of key design parameters consisting of the number of blades, blade chord length, helical angle, and J-shaped blade on the performance and self-starting ability of a Darrieus VAWT. Furthermore, implementing an efficient optimization model to obtain maximum power based on the numerical findings. To achieve this, two different numerical modeling approaches, namely Computational Fluid Dynamics (CFD) and Double Multi-Streamtube (DMST), have been applied. The results indicated that employing a higher blade number and chord length enhances the starting capability of the turbine. Moreover, increasing the helical angle to 60° reduces the generated torque fluctuations. Inspired by the design of the Savonius turbine, the implementation of a J-shaped airfoil boosted the Cp at low TSR. Finally, the Kriging optimization method has been employed to optimize the design parameters explored through CFD analysis. The outcomes showed that the optimum configuration of the examined Darrieus VAWT comprises a 3-bladed rotor with a blade chord length of 0. 04 m and helical angle of 0° and a J-shaped blade length ratio of 0. 68. This configuration yields an 10% increase in efficiency at the optimum TSR.

The aerodynamic of Vertical Axis Wind Turbine (VAWT) is more complex than a horizontal axis wind turbine. In the present research, the combination of the Wagner unsteady aerodynamic model, static stall and Double Multiple Stream Tube (DMST) aerodynamic model have been used to investigate the aeroelastic behavior of VAWT. For this purpose, the DMST aerodynamic model, which is related to the vertical axis wind turbine aerodynamics model, has been used to obtain two parameters of the angle of attack and relative velocity. Then these two parameters have been applied to the Wagner nonlinear aerodynamics, which considers the effect of the static stall. This flexible nonlinear presented model based on DMST is called NFDMST aerodynamic model. One-degree of freedom of typical section and two-degree of freedom model have been investigated for static aeroelasticity and dynamic aeroelastic behavior, respectively. The VAWT blade experiences a variety of attack angles and relative velocity in a spin, so the goal is to obtain the instability velocity in a different position and consider the effect of aerodynamic and structure nonlinearity. The results show that the nonlinear aerodynamic model has accurate results and the aeroelastic design condition associated with-90degree azimuth angle, in which the minimum instability velocity is 45. 2m/s. In addition, the change of instability speed of rotating airfoil in a spin is about 6%.

The present research investigates the torsional aeroelasticity of the blade of an H-type vertical axis wind turbine subject to stall and post-stall conditions in various Reynolds regimes, which is experienced by the blade in a full revolution. In order to simulate the aerodynamics, a new model based on a combination of the Double Multi Streamtubes (DMST) model and the nonlinear multi-criteria Cl- equations, which is depended on the local Reynolds number of the flow, has been proposed. The results indicate that using of multi-criteria function dependent on the Reynolds number for the Cl- curve has improved the prediction of the torsional behavior of the blade in azimuthal rotation of the blade compared to using single-criterion functions and linear aerodynamics. The blade’ s aeroelastic torsion has been studied for various TSR values.

This research evaluates two types of vertical axis turbines from both an aerodynamic and economic perspective. The turbines used in this study have straight (H-shaped) and angled (V-shaped) blades, with equivalent dimensional characteristics that are suitable for the climatic conditions and average wind speed distribution in Zahedan city. The aerodynamic evaluation of the turbines was conducted using the semi-analytical DMST method. The results indicate that the V-shaped turbine generates significantly less power than the H-shaped turbine due to the reduction of the effective area of the turbine and the torque produced by its rotor. However, during startup, the V-shaped turbine exhibits about seven times less negative power than the H-shaped turbine, which improves the overall startup process. Economically, the cost of energy production per kWh for a V-shaped turbine is approximately 20% lower than that of an H-shaped one. This makes the V-shaped turbine a more suitable option for urban and small-scale applications.

Using some small wind turbines which is both simple in fabrication and efficient in wind energy extraction is very attractive. In this research wind energy potential has been assessed for 3 distinct locations in Iran composing Tehran, Zahedan and Manjil. Consequently, a typical H-rotor wind turbine is being localized based on these locations climate. A baseline design has been introduced and a semi-analytical 3D method has been developed for design improvement and geometric modifications. The DMST algorithm has been embedded in the code and the validation analysis is being presented. Parametric study and the corresponding results have been investigated including the effect of wind velocity, number of blades, chord length and blade dimension. The performance issues are power coefficient and force coefficient. based on the results presented it has been revealed that changing geometric variables can improve the turbine characteristics by 20-40 percent. Therefore, it is possible to propose some localized layouts based on the spatial wind profile and wind power study. one may start with the presented framework and utilize the Genetic algorithm in order to achieve an optimized design in continuation.

One of the most important issues in cognitive psychology is the relationship between emotion and cognition. The aim of this research was to investigate the effects of happiness and sadness on girls’ and boy s’ decision making strategies and duration of decision making. Participants were 54 children, 5 to 6 years old (27 boys and 27 girls) from Shiraz kindergartens. Children were assigned to one of “happiness inducing”, “sadness inducing” and control group s. Animation was used for inducing emotions in the experimental groups and was presented individually to the children. After inducing the emotions, the Positive and Negative Affect Schedule - Expanded Form (PANAS- X) was used for assessing sadness and happiness in the experimental groups. Also, decision making strategies was measured by the Decision Making Strategies Task (DMST). This task was performed individually, in the experimental and control groups. Results showed that emotional conditions did not significantly affect children's decision making strategies. Gender had a significant effect on children's decision making strategies. Boys had higher scores in decision making strategies than girls. Additionally, results indicated that emotional conditions had a significant effect on children's decision making duration. Decision making duration in the sadness group was lower than in the control group. Gender did not have a significant effect on decision making duration. This study provides further insight into the relationship between emotion and decision making in children.