عنوان مقاله [English]
In recent years, wind energy has received a lot of attention and many advances have been made in changing wind energy to electrical energy and mechanical energy. Wind energy is sustainable energy that plays an important role in increasing the energy production of countries and international policies against climate change. Most countries around the world are now facing environmental problems due to the consumption of fossil fuels, so they have turned to clean energy. For this reason, one of the best and most economical methods available is to use wind power and wind turbines. The development of this industry is possible when it is compared to other sources of economic energy, and considering the cost-free production of this energy, it is of course economical. Being economical means balancing the costs of investing and getting energy through it. The most important parameter influencing the construction of a wind turbine is the selection of the best airfoil. A wind turbine is a device that converts wind energy into electrical energy. There are two types of wind turbines available: horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT). HAWT is very useful in generating electricity but it also has problems, for example it needs YAW mechanism, regular maintenance, additional cost in strengthening the tower structure, maximizing the rotor diameter, number of rotor blades, loud noise, wind direction it is suitable and dangerous for migratory birds. The ability to control wind flow in order to form the desired change is of great technological and practical importance. More than any other topic in fluid mechanics, it is now pursued by researchers and engineers to come up with methods for better efficiency and lower flow control. Wind characteristics in urban areas are significantly affected by the roughness of urban areas. It creates more complex properties for wind that the separation of wind flow is influenced by buildings in response to strong multidimensional winds in urban environments. Due to the disadvantages of HAWT and VAWT wind turbines and wind characteristics in urban areas, researchers have started to build cross-axis wind turbines. The CAWT wind turbine is more efficient in terms of wind turbine performance in different directions of urban areas. It can receive wind energy in horizontal and vertical directions. CAWT has the ability to overcome the disadvantages of any type of wind turbine and because of CAWT's ability to receive wind energy regardless of wind direction, it is a good alternative to conventional VAWT wind turbines in urban areas, thus increasing the performance of wind turbines.
The initial design of the CAWT wind turbine consists of 3 vertical blades and 6 straight horizontal blades as shown in Figure 3. The CAWT wind turbine consists of a support frame, a turbine rotor assembly mounted on a support frame and rotating on its vertical axis. To change the nature of kinetic energy from the movement of the turbine rotor to electrical energy and mechanical energy, an electric generator is connected to the turbine assembly. In this study, the CAWT wind turbine with 3 vertical shaft blades NACA 0018 and 3 horizontal shaft blades NACA 4412 which are connected to each other through special connections were evaluated. The advantage of CAWT is that it can work with the airflow on both sides through the vertical axis airfoil and from below and above the turbine through the horizontal axis airfoil. The horizontal axis blades act as the CAWT radial arms and attach the hinges to the vertical blades. Joints are used to pair horizontal blades and vertical airfoil blades. Horizontal wind can be picked up from all directions by vertical blades. The vertical wind flow from the bottom of the turbine can be received with horizontal blades, which improves the spontaneous ability to start the turbine and create aerobic force. This force reduces the bearing friction in the generator and thus increases the life of the wind turbine. In urban areas, wind currents are complex due to roughness and tall buildings, which makes it difficult to separate wind currents from each other. CAWT is superior to other wind turbines in this situation and receives wind currents from both sides. These wind conditions that are not predictable, especially in urban areas, require a special wind turbine that uses the potential of wind power. In this study, SolidWorks and Ansys Fluent software were used. First, the turbine was designed in SolidWorks software and Ansis Fluent software was used to analyze the wind flow. The first step to design or simulate a wind turbine is to choose wind conditions such as wind speed, direction and thickness, for which meteorological information from Mazandaran province was used. In this research, we intend to work on the full router model and obtain the effects of wind speed on it, we will obtain the production power and production torque of each region. According to the two formulas of output power and torque, the output power and torque of the turbine was considered in four wind stations, including Sari, Dasht-e Naz, Bandar Amirabad and Gulogah, where the average wind speed of the previous year was set for software input.
In this study, a 5 kW wind turbine with two types of airfoils in accordance with the climatic conditions of Mazandaran province was simulated using Ansys Fluent software. The steps were done in such a way that according to the meteorological data of four stations in Sari, Dasht-e Naz, Amirabad and Gulogah, the average annual wind speed in these areas was determined. The turbine was designed according to the dimensions specified in the SolidWorks software environment. The output of SolidWorks software is entered into Ansys Fluent software to solve the continuity and momentum equations for the control volume by applying the considered boundary conditions. The results in Ansys Fluent software show the force equal to 2089 (Newton) and the torque equal to 592.9 (radian joule). As a result, the power of the turbine is equal to 12.415 (kW). In this part, the result is the turbine production capacity of this research is about 2.5 times more than the vertical axis turbine, which has the same characteristics as the wind turbine of this research.