| In order to explore the influence of horizontal axis wind turbine blade tip structure changes on the distribution characteristics of wind turbine noise sources,near-field acoustic holography and far-field beamforming methods are used to collect wind turbine noise signals at different incoming wind speeds and rotational speeds,and analyze The effect of blade tip structure changes on the sound pressure level and sound source location of wind turbine noise sources.The following work has been carried out:(1)The Wilson design method was adopted,and the S825 airfoil was selected to design the unmodified blades and the V-shaped and W-shaped blade tip structure blades.The blades were manufactured using3 D printers,and the external characteristics of the blades were tested in the wind tunnel laboratory to analyze the modifications.The influence of the rear blade tip structure on the output power and wind energy utilization coefficient of the wind turbine.The test results show that the two blade tip modified blades can improve the output power and wind energy utilization coefficient of the wind turbine to different degrees at the rated wind speed.At the rated wind speed,the three blades meet the design requirements;the two modified blade tips can make The output power of the wind turbine is5.71 %～10.18 % higher than that of the unmodified wind turbine,and the wind energy utilization coefficient is 13.85 %～18.58 % higher than that of the unmodified wind turbine.Among the three blades,the average output power of the W-shaped tip structure wind turbine is The average wind energy utilization coefficient is the highest,with the best output power and wind energy utilization coefficient.(2)Carried out the location and identification test of the wind turbine noise source.The acoustic array test equipment was used to collect and analyze the wind turbine noise source data using the near-field acoustic holography method and the far-field beamforming method.The test results show that the high-frequency noise sources of wind turbines are mainly distributed near the r/R=0.51～0.76 area,and the low-frequency noise sources at the blade tip are mainly concentrated near the d=1.1～16.0 cm area.The sound pressure level of wind turbine aerodynamic noise sources increases with the increase of wind turbine aerodynamic load and centrifugal force load.The higher the noise source frequency,the greater the increase,and this trend varies with the centrifugal force load.The aerodynamic load changes more obviously;the noise source of the wind turbine is on the blade,and the distribution position is mainly concentrated in the area from the middle of the blade to the tip of the blade,and the distribution is asymmetrical;the position of the noise source on the blade does not follow the wind turbine aerodynamics The load and centrifugal load change,but under the same working conditions,as the frequency of the noise source increases,the sound pressure level of the noise source decreases,and the position of the sound source moves regularly from the middle of the blade to the tip of the blade along the span of the blade.(3)The location and identification test of wind turbine noise sources with different blade tip structures was carried out to explore the influence of blade tip structure changes on the sound pressure level and sound source location of wind turbine noise sources.The test results show that the two blade tip modified blades are both It has a good noise reduction effect.The higher the frequency of the noise source,the more significant the noise reduction effect of the modified blade;the noise reduction effect of the two blade tip modified blades increases with the increase of aerodynamic load and centrifugal load,and this The trend is more obvious with the centrifugal load than with the aerodynamic load;the noise reduction effect of the W-shaped blade tip is better than that of the V-shaped blade tip in each noise frequency band.In the same frequency band,compared with the unmodified wind turbine,the noise source positions of the two blade tip modified wind turbines move along the span of the wind turbine blade toward the blade tip,and the higher the noise source frequency is caused by the tip modification The greater the moving distance;in the same noise frequency band,the noise source of W-shaped blade tip structure blades moves a greater distance in the span direction of the wind turbine blade toward the blade tip than the V-shaped blade tip structure blade noise source,but the moving distance does not vary with the aerodynamics Changes in load and centrifugal load.Through the analysis of the test results,it is found that the two modified blade tip structures can make the noise source position move to different degrees along the blade spanwise direction towards the blade tip,and can reduce the noise source sound pressure level of wind turbine,and the W-type blade tip structure has the best noise reduction effect.A tip modification method with excellent aerodynamic performance and remarkable noise reduction effect is found,which provides a new idea for the noise reduction design of wind turbine. |
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