基于CFD模拟的风力机叶片气动噪声研究

发布时间：2018-05-01 19:50

本文选题：风力机叶片 + 气动噪声　；参考：《华北电力大学》2015年硕士论文

【摘要】：风力机气动噪声对环境的影响日益突出,引起了人们的广泛关注。研究风力机叶片气动噪声问题对减小风力机对环境的影响具有重要意义。随着计算方法的改进和计算机计算能力的提高,数值模拟成为研究风力机气动噪声的主要手段。本文利用Fluent软件对NACA0012直叶片进行了CFD模拟。模拟了不同攻角、不同尾缘厚度条件下叶片绕流场,分析了叶片尾缘区域及尾迹流场的流动结构。基于CFD计算结果采用FW-H方法和FFT变换,得到了叶片气动噪声的声场分布,分析了相关监测点气动噪声的变化及衰减规律,获得以下结论：(1)叶片尾缘区域及分离区存在较大的压力脉动,所以尾缘区域和分离区是叶片产生气动噪声的主要来源。(2)在攻角较小时,监测点声压级会出现明显的峰值,噪声离散特性较为明显。攻角大于6°后,声压级没有明显的峰值,其特征主要体现为噪声的宽频特性。所以随着攻角的增大,离散噪声会逐渐消失,噪声频谱主要体现为宽频噪声特性。而且随着攻角的增大,低频噪声会逐渐降低,高频噪声有所增大。(3)在小攻角时,在低频段的主频频率与尾缘处的旋涡脱落频率基本一致,这说明尾缘脱落涡是引起声压级在低频处出现峰值的主要因素。(4)在一定攻角的情况下,随着尾缘厚度的增大,在低频段离散噪声有所增强,在高频段噪声声压级也逐渐增大。所以翼型尾缘厚度越大,风力机叶片的气动噪声越大。
[Abstract]:The influence of wind turbine aerodynamic noise on the environment is becoming more and more prominent, and people pay more attention to it. It is of great significance to study the aerodynamic noise of wind turbine blades to reduce the impact of wind turbine on the environment. With the improvement of calculation method and computer computing ability, numerical simulation has become the main method to study aerodynamic noise of wind turbine. In this paper, the CFD simulation of NACA0012 straight blade is carried out by using Fluent software. The flow field around the blade with different attack angles and thickness of the tail edge is simulated and the flow structure of the blade tail edge and wake flow field is analyzed. Based on the results of CFD calculation, the sound field distribution of blade aerodynamic noise is obtained by using FW-H method and FFT transform. The variation and attenuation law of aerodynamic noise at relevant monitoring points are analyzed. The following conclusions are obtained: (1) there is a large pressure pulsation in the tail edge and separation zone of the blade, so the tail edge region and the separation area are the main source of aerodynamic noise generated by the blade. 2) when the angle of attack is small, the sound pressure level at the monitoring point will appear obvious peak. The discrete characteristic of noise is obvious. When the attack angle is greater than 6 掳, the sound pressure level has no obvious peak value, and its characteristic is mainly the broadband characteristic of noise. As the angle of attack increases, the discrete noise will gradually disappear, and the spectrum of the noise mainly reflects the characteristics of wide-band noise. With the increase of the angle of attack, the low frequency noise will gradually decrease, and the high frequency noise will increase. 3) when the angle of attack is small, the frequency of the main frequency in the low frequency band is basically the same as the frequency of vortex shedding at the tail edge. This shows that the tail edge shedding vortex is the main factor that causes the peak of sound pressure level at low frequency. At a certain angle of attack, with the increase of tail edge thickness, the discrete noise increases in low frequency range, and the noise sound pressure level increases gradually in high frequency range. Therefore, the greater the thickness of the tail edge of the airfoil, the greater the aerodynamic noise of the wind turbine blade.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM315

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