Advanced Materials Research Vols. 512-515

Abstract: With the power increase of the wind turbine, the scale of the blade is increasing, further improving the performance of the blade, improving the stiffness and stability of the blade, inhibiting the vibration and noise of the blade and reducing the blade weight has become an problem urgently needed to be solved with for the design of the large wind turbine blade. The unique external shape of organisms, the perfect unity of the function, structure and material, the excellent capability for adapting the environment, also provides an inexhaustible inspiration for the bionic design of wind turbine. Applying the biological non-smooth and self-cleaning effect and imitating the biological medial axis pattern structure, self-adaptive characteristics conduct the bionic design of the wind turbine blade, it can effectively realize drag-reduction and lift enhancement for the blades, noise reduction, lightweight, and can improve the self-adaptive ability, resisting wind and sand, preventing icing up. Paying attention to research on biological mechanism, perfecting the bionic design theory, implementing the multidisciplinary design optimization, strengthening the research on model, have an important significance on improving the bionic design effect for the wind turbine blade and promoting the bionic engineering application.

Abstract: The buckling of 2.5MW horizontal axis wind turbine tower tube (5.8m*3.2m*95.2m) is studied by theoretical analysis and numerical simulation. The buckling critical value of tower under axial force is found by theoretical method. The buckling modal of tower under axial force, wind pressure, bending moment and lateral force is simulated by ANSYS software. The buckling of tower with opening and frame at the bottom is also simulated by ANSYS software. The results show that both load and opening have influence on buckling performance, different load and opening have different impact to buckling of tower tube.

Abstract: The purpose of this paper is to find the optimum design attack angle for fixed-pitch variable-speed wind turbine blade design, given the base-line wind turbine and the blade airfoil. Aerodynamic characteristics, i.e. lift and drag coefficients and lift to drag ratio, of the wind turbine, are analyzed. Two design attack angles along with the base-line attack angle (with maximum lift to drag ratio) are selected for the wind turbine blade design exercise. Blade design outcomes are analyzed and compared along with load performance and power performance. This paper is possibly the first attempt to determine the optimized design attack angle for maximizing annual energy production, given the base-line wind turbine and the blade airfoil.

Abstract: Green energy resources are more and more fashionable and focused. Among of them, small wind turbine is popular and with many customers because it has an unique feature . The design and calculation on thickness of airfoils were studied in order to raise its life and reduce weight. In the premise of strength, the lighter, the better. This paper studied the aerodynamic performance of the airfoil under the Low-Reynolds and analyzed fluid-structure interaction effect under three different attack angles. The numerical simulation approach addresses unsteady Reynolds-averaged N-Stokes solutions and covers transition prediction for unsteady mean flows. The computational result and the analysis show that the fluid-structure interaction is an important issue to consider while designing the wind turbine blade. The results may provide technical reference for the further wind turbine design.

Abstract: Emerging markets need small sized VAWT (vertical-axis wind turbine) for residential energy supplement. MingDao university wind power R&D team has developed a 4kW VAWT system is response to this need. The development items include innovative blades, generator, power control and mast design. The newly developped 4kW VAWT system demonstrates superior performance. The average VAWT efficiency is 0.31 and the average Cp is 0.39. The preliminary results showed this approach has potential for future applications.

Abstract: Numerical investigation of large thick and low Reynolds airfoil of wind turbines by mounting indented Gurney flaps was carried out. The influenced rules of the position of Gurney flaps on the aerodynamic performance of airfoil under same height of flaps were achieved, and the optimal position of Gurney flap was presented. At last, the mechanism of wind turbine performance controlled by Gurney flap was discussed. The results can provide the theoretical guidance and technical support to wind turbines control in practical engineering.

Abstract: In recent years, wind energy develops rapidly in China and its comprehensive management research deepens continuously. This paper studies the wind energy level and summarizes the current development situation of our country. The study puts forward a forecasting analysis using Grey Forecasting Theory, and proposes several suggestions for the comprehensive development. The result has reference for improving the management level of the wind power.

Abstract: Offshore wind farm development direction is from shallow sea to sea . In this paper, according to the current on the wind power base also can not meet the requirements of the problem deep, analysed the base cost will not be particularly high reason. In view of the Hainan offshore wind power, put forward the design train of thought, the analysis obtained an ideal design model.

Abstract: Under the condition of energy shortage and environment worsen so far, wind power generation has got much improvement. The article makes research to main problems existing in wind power grid-connecting, which inludes the following items: 1) Main types and characteristics of present grid-connected wind generators; 2) Main difference of the operation characteristics between grid-connected wind plant and conventional engergy power plant; 3) The influence to power quality and power system stability caused by grid-connected wind plant and the measures taken to deal with such influence; 4) The particularity of wind power enterprise in China; 5) Domestic and foreign standards’ main requirements to wind power grid-connecting; 6) Three important issues needed urgently research: wind generator and wind plant modeling, wind power forecasting, cooperating control technics between wind plants and power grid. The development of wind power enterprise will bring people remarkable economic benefit and social benefit.

Abstract: This study discussed the structural analysis of blades of a small horizontal-axis wind turbine (HAWT). The computational fluid dynamics (CFD) is combined with the computational solid mechanics (CSM) into the one-way fluid-solid interaction. The aerodynamic force calculated by CFD is loaded on the structure, and the structural deformation and stress distribution are calculated using CSM. The physical model in the study is a HAWT blade with the rated power output of 500 W, and the material is engineering plastics. The Young's modulus of material is estimated according to the result of blade static load test. The accuracy of structural analysis is verified, and the blades in rated operating state are analyzed for fatigue failure. The blades in no-load running and rotor parked state are analyzed for ultimate strength. The blades of a wind turbine have large length-to-diameter ratio, and the structure approximates to a cantilever. The accuracy of linear analysis is good under a small load. However, as the load increases, the effect of geometric deformation should be considered to improve the precision of analysis. Therefore, the geometrical nonlinearity is used in this study to analyze the structure of blades in three operating states. The results showed that the safety of blades can meet the IEC 61400-2 international standard. In addition, the required safe distance between blades and tower is estimated at 157 mm according to the critical deformation analysis. According to the natural vibration modal analysis, the blades should be prevented from running at the rotating speed of 744 rpm that causes resonance for long.