Experiment Of The Strain Of The Wind Turbine Blade Based On FBG Measurements

With the development of wind power industry in recent years, global wind power technology is becoming increasingly mature. As the core component of the wind turbine, blade is very important, the structural characteristic of which is the premise of long-term safe and efficient operation of the system. blades not only withstand strong wind load, but also are subjected to gas erosion, the impact of sand particles, strong ultraviolet radiation and other external erosion, cracks in the harsh environments often produce.Therefore, it’s necessary for real-time condition monitoring of wind turbine blade strain. Fiber grating sensor has many advantages, such as, simple structure, small size, high precision, high sensitivity, insulation, anti-electromagnetic interference, resistance to high voltage, chemical corrosion, high temperature, etc. so sensor networks can be composed of distributed measurement. It meets the sensing applications requirement of blade running in complex environment.This thesis focuses on the strain monitoring application of fiber Bragg grating sensor in wind turbine blades, and is sponsored by the National Natural Science Foundation (51175390), Wuhan City Subject Leaders Plan Fund (200951830557) and Wuhan University of technology Independent Innovation Research Fund (2010-ZY-JD-007). The air flow field, surface static pressure, static load strain and strain response under different frequency excitation of200W small wind turbine blade are researched in the paper. The main contents are as follows:1. The two-dimensional airfoil flow field and three-dimensional rotating flow field of blade is simulated; the airfoil blade two-dimensional flow field and surface static pressure distribution in the angle of attack of0°to20°is obtained. The blades three-dimensional rotating flow field and surface static pressure distribution under rated condition operation is analyzed2. According to the results of the analysis of the flow field, the aerodynamic forces of different cross-section position of0.2r-r fragments of blade in7m/s~12m/s wind speed is calculated, the static load strain experiment of the blade is accomplished in the form of cantilever by fiber Bragg grating sensors. The strain distribution of blade surface and the relationship between the maximum strain and the load are researched.3. The frequency of blade vibration is given by exciter, the first natural frequency of the blade is measured by acceleration sensor, the strain response from30Hz to80Hz is measured by the fiber Bragg grating sensors. The strain response of each point of the blade surface under different frequencies and the strain response distribution under the first natural frequency are researched.