| The thesis is supported by the National Natural Science Foundation of China Project"Wind Tunnel Experiment and Research on Series Blades of Concentrated Wind Energy Turbine" [NO: 59776033] ,and as a part of this project, the design of the blades for megawatt-class WTGS(Wind Turbine Generator System) is researched. With the prerequisite of correct wind speed description in the wind farm, taking the aerodynamic performance and synthesis as optimization objects, optimal design methods for the WTGS'rotor blades have been proposed. In order to solve these optimization problems, the high-level computer programming language Visual Basic6.0 has been adopted as the main development tool in the software. Taking an area in Inner Mongolia as the wind farm for blades design, 1.5MW blades named as SJ1.5 is designed. External shape comparison and characteristics simulation have been made between this designed blades SJ1.5 and a foreign common blades NR1.5. Then the resemble models of these two kinds of blade are designed and manufactured, and output power characteristics tests of these models have been carried with in-truck-test method. The main works and innovative contributions of this dissertation are as follows:(1) Weibull distribution is a kind of common distribution function for defining wind speed; it can describe the wind speed accurately by its two parameters. In order to determine these two parameters, two methods of gradient direction search method and circulation test algorithm are proposed. Illustration by example shows the feasibility of these two methods, but the step length of gradient direction search method is 2mr or 21m r in step m, which makes the calculation more precise as well as reduces the times of calculation. Mathematical expectation of wind speed based on Weibull distribution function, is a kind of integration on the infinite interval. Using Gauss-Laguerre integral formula to solve, taking n nodes, the algebraic accuracy can be achieved 2n-1 times.(2) Mathematical models of synthesis optimization and external blade shape optimization are proposed. The shape modification constraints are presented on constraint conditions that modify chord by the key parameter of aspect ratio and conditions that modify thickness by strength. Solution methods to the external blade shape constrained optimization problem are given both on aerodynamic constraints and shape modification constraints, and it makes the shape of blade much smoother by cubic spline interpolation to the design results. As an example, wind turbine blades SJ1.5 for variable pitch horizontal axis wind turbine 1.5MW are designed. Compared with a type of foreign general-purpose blade NR1.5, the layouts of chord length, twist angle and relative thickness are substantially coincident. The average output power, power coefficient and annual energy production of blade SJ1.5 are 2.32%, 3.13% and 2.45% times greater than that of blade NR1.5.(3) 6 groups of output characteristic tests and simulations of the resemble models MSJ and MNR for blades SJ1.5 and NR1.5 in three kinds of setting angle 10.5°, 30.5°, 50.5°are carried out. Comparative analysis to the simulated results and test results shows that the numerical simulation and experimental results are basically the same in the effective testing system; analyzed on the 4 major performance parameters of power, power coefficient, torque coefficient and the annual energy production, performance of the system under setting angle 10.5°is superior to the others; compared with the model MNR, the performance of model MSJ shows a certain superiority.
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