Search Results (4)

In this paper, based on the lift-type wind turbine, an adaptive double-drive lift–drag composite vertical-axis wind turbine is designed to improve the wind energy utilization rate. A drag blade was employed to rapidly accelerate the wind turbine, and the width of the blade was adaptively adjusted with the speed of the wind turbine to realize lift–drag conversion. The aerodynamic performance analysis using Fluent showed that the best performance is achieved with a blade curvature of 30° and a drag-type blade width ratio of 2/3. Physical experiments proved that a lift–drag composite vertical-axis wind turbine driven by dual blades can start when the incoming wind speed is 1.6 m/s, which is 23.8% lower than the existing lift-type wind turbine’s starting wind speed of 2.1 m/s. At the same time, when the wind speed reaches 8.8 m/s, the guide rail adaptive drag-type blades all contract and transform into lift-type wind turbine blades. The results show that the comprehensive wind energy utilization rate of the adaptive dual-drive lift–drag composite vertical-axis wind turbine was 5.98% higher than that of ordinary lift-type wind turbines and can be applied to wind power generation in high-wind-speed wind farms. Full article

The additive processes used in the manufacture of components for unmanned aerial vehicles (UAVs), from composite filaments, have an important advantage compared to classical technologies. This study focused on three-dimensional design, preliminary aerodynamic analysis, fabrication and assembly of thermoplastic extruded composite components, flight testing and search-rescue performance of an UAV. The UAV model was designed to have the highest possible structural strength (the fuselage has a structure with stiffening frames and the wing is a tri-spar), but also taking into account the limitations of the thermoplastic extrusion process. From the preliminary aerodynamic analysis of the UAV model, it was found that the maximum lift coefficient of 1.2 and the maximum drag coefficient of 0.06 were obtained at the angle of attack of 12°. After conducting flight tests, it can be stated that the UAV model, with components manufactured by the thermoplastic extrusion process, presented high stability and maneuverability, a wide range of speeds and good aerodynamic characteristics. The lack of this type of aircraft, equipped with electric motors, a traffic management system, and a thermal module designed for search-and-rescue missions, within the additive manufacturing UAV market, validates the uniqueness of the innovation of the UAV model presented in the current paper. Full article

The research on tidal-current energy-capture technology mainly focuses on the conditions of high flow velocity, focusing on the use of differential pressure lift, while the average flow velocity in most sea areas of China is less than 1.5 m/s, especially in the marine aquaculture area, where tidal-current energy is needed to provide green energy locally. Due to the low flow velocity of this type of sea area, it seriously affects the effect of differential pressure lift, which is conducive to exerting the effect of impact resistance. In this regard, the coupling effect of the differential pressure lift and the impact resistance on the blade torque is comprehensively considered, this research puts forward the design method of the lift-–drag-composite thin-plate arc turbine blade. Based on the blade element momentum (BEM) theory and Bernoulli’s principle, the turbine dynamic model was established, and the nonlinear optimization method was used to solve the shape parameters of the turbine blades, and the thin-plate arc and NACA airfoil blade turbines were trial-produced under the same conditions. A model experiment was carried out in the experimental pool, and the Xiangshan sea area in Ningbo, East China Sea was taken as the experimental sea area. The results of the two experiments showed the same trend, indicating that the energy-harvesting performance of the lift–drag-composite blade was significantly better than that of the lift blade under the conditions of low flow velocity and small radius, which verified the correctness of the blade design method, and can promote the research and development of tidal energy under the conditions of low flow velocity and small radius. Full article

Wind power plants are considered as an ecologically-clean source of energy. However, manufacturing processes cannot be treated that way. Manufacturing processes consume huge amounts of electrical and thermal energy and significant amount of materials, e.g., steel, polymers, oils, and lubricants. All of the above could be potentially harmful for environment. There are not many works and publications regarding life-cycle analysis of wind power plants. This study’s objective is to use LCA (Life Cycle Assessment) to the manufacturing and utilization of a specific drag force-driven wind turbine. The discussed innovative wind turbine is of the type that assures safety for prosumer application. Drag force-driven turbines become more heavy than other types of lift driven turbines, but at the same time, their characteristic provides opportunity to use easily recyclable materials instead of materials like plastics or composites. The wider look through LCA tools, may change the perspective of view at that type of wind turbines. Analyzed turbine has capacity of 15 kW and is located in Poland. LCA was carried out using Eco-indicator 99 method in eleven impact categories. Among all of the turbine components, the highest negative impact was noted in the case of the tower. The wind turbine under consideration is characterized by high recycling potential. According to the presented research, recycling provides around 30% reduction of the environmental impact. Full article