An experimental investigation of power generation efficiency and wake characteristics on a miniature wind turbine with different chord lengths

Abstract

The object of this study carried out a wind-tunnel experiment to explore the effect of turbine blade solidity on power generation and wake characteristics The experiment was carried out in a wind tunnel and we set up a miniature wind turbine inside The turbine model involved a three-blade rotor and three two-blade rotors with different solidity Instruments adopted here include the Cobra Probe anemometer and the laser tachometer for measurements In the experiment the measured data include the voltage value of the turbine generator and the rotating speed of the blades And we compared the results of measurements including the power output power coefficient and the characteristics of the turbine wake by using different blades Experiments have been performed to measure the electrical circuit resistance values of 10 20 40 and 60 ohms We established the corresponding relationship between the inflow wind speed and the rotational speed and then we established the relationship between the rotational speed and the coefficient of performance through calculation From the above results it can be known that when the resistance value is 20 ohms and the inflow condition is 6 m s-1 the maximum value of the power coefficient is 0 208 with the 3B-S100 wind turbine blade We can know from the relationship between output work and speed When using the same resistance for measurement even if fan blades with different chord lengths are used in the measurement the output power and speed will show the same trend In the case of different loop resistances there will be a significant difference between the distribution curve of output power and speed Therefore we calculated torque constant by the measured data that we can derive the relation of power output the value of resistance and the rotation speed We set up 57 sampling points along the spanwise direction in the measurement Besides we investigate the near wake characteristics included the averaged streamwise velocity turbulence intensity and momentum flux on the streamwise location of X/D = 1 3 and 5 We found that the turbulence intensity measured with the 3B-S100 blade is lower than the turbulence intensity measured with the 2B-S100 and 2B-S83 blades In the real wind farm we usually consider the interaction between the upstream turbine and downstream turbine The lower turbulence intensity means the downstream turbine has less fatigue loading caused by the wake of the upstream turbine That is also one of the reasons why the wind turbines in a real wind farm adopt the 3-blade rotor Finally we used the velocity data of inflow and the wind data of the sampling point behind the blade tip to perform the spectrum analysis We can see that there are several peaks exist in the distribution of the power spectrum The main reason is that the force on each blade is non-uniform

Date of Award	2020
Original language	English
Supervisor	Yu-Ting Wu (Supervisor)