Xin Cai

Static and Dynamic Characteristics Study of Wind Turbine Blade

Structural analysis of wind turbine blade is a necessary part in the process of blade design. Based on the ANSYS software, the stress and strain distribution analysis of a kind of 1500kW horizontal axis wind turbine blade is carried out at the action of ultimate flapwise loads, the vibration mode shapes of this blade are also analyzed in this paper, thus providing some reference value for the larger-scale wind turbine blade on structural design.

Multi-objective optimization and fuzzy evaluation of a horizontal axis wind turbine composite blade

The aerodynamic and structural coupling optimization of a 1.5 MW wind turbine blade is conducted based on the multi-objective genetic algorithm NSGA-II. Through the optimization of the chord lengths, the twist angles, and the number of laminating, an optimal solution set is obtained, in which the blade is lighter and the generating capacity is higher. Particularly, the fuzzy evaluation is performed after the multi-objective optimization to select the best design adapting to the specific working environment. A new method to determine the membership is proposed instead of experts vote when the fuzzy evaluation is carried out, which contributes to decreasing subjectivity, and saving much time, human and material resources. Hopefully, the method combining the multi-objective optimization and the fuzzy evaluation can be applied to the other similar projects in engineering.

Anti-flutter optimization design of airfoil for wind turbine blade

An anti-flutter optimization design of DU 98-W-210 airfoil for wind turbine blades is carried out by employing the particle swarm optimization algorithm. As is well known, the increase in the torsional blade stiffness, which is in proportion to the polar moment of inertia, will improve the anti-flutter ability of airfoil. Thus, maximizing the polar moment of inertia is selected as the design objective, within the aerodynamic performance constraints (i.e., the lift-to drag ratios in a wide range of AOAs (Angle of Attack) should not be lower than the original value). The commercially available software CFX is employed to calculate the flow field by solving the Reynolds-averaged Navier-Stokes equations coupled with the shear stress transport turbulence model. The results show a significant improvement in both the polar moment of inertia and the lift-to-drag ratios in a wide range of AOAs of the optimized airfoil compared to the original DU 98-W-210 airfoil.

Experimental Study on the Shear Strength of Cement-Sand-Gravel Material

An experimental study on the shear strength development of cement-sand-gravel (CSG) material was carried out using triaxial compression tests. The effects of the cementing agent content, aggregate content, and gradation on the shear strength of CSG material were analyzed. The shear strength remarkably increased with increasing cementing agent content and aggregate content for a given confining pressure. The increase in shear strength with increasing cementing agent content far exceeded that with increasing aggregate content. However, the stress-strain curves and shear strength changed only slightly when the aggregate gradation for CSG material was adjusted. Based on the test data, a strength criterion for CSG material is proposed as a function of the cementing agent content, aggregate content, and shear strength of the aggregate gradation.

Hoist Safety Risk Assessment Model Research

Considering the various factors which influenced the safety of hoist system, and the general objective which was the failure probability of hoist system, it established the safety risk assessment model for hoist system. Then it used the time-varying effect to forecast the failure probability and crash damage of hoist system. It constructed the evaluation index system, and used the AHP method, the fuzzy mathematics method and the method of expert advice on weight distribution at various levels. Based on the evaluation and analysis of Zhuzhuang reservoir projects on the gate crane, it proved that the safety risk assessment model for hoist system was scientific, safety and reliability.