钢轨声辐射特性的数值计算方法

声辐射系数是轮轨噪声预测的重要参数,用边界元方法预测声辐射系数,并以钢轨为例,计算了垂向和横向声辐射系数。计算结果表明:625 Hz以下,钢轨的横向、垂向声辐射系数随频率呈线性变化;1000 Hz以下钢轨的横向声辐射系数强于垂向声辐射系数;1000 Hz以上垂向声辐射系数大于横向声辐射系数,垂向声辐射系数在1000 Hz以上有两个峰值,分别在2000 Hz和5000 Hz;在1500 Hz~3000 Hz范围内钢轨垂向声辐射系数较大,这个频率内以垂向振动对声的贡献最大,这也是钢轨噪声的主要贡献频率;在5000 Hz附近要弱于2000 Hz附近的声辐射系数。该方法能很好地预测结构的声辐射系数,较好地解决了振动与噪声之间的联系问题,为轮轨噪声预测开辟了一条途径。

The Prediction of Acoustics Radiation Characteristics of Rails by Boundary Element Method

Acoustic radiation characteristics of rails are the keys for predicting wheel-rail noises.This paper presents a boundary element method(BEM) that can be used to predict rail radiation coefficients.The results show that when the rail vibration frequency is below 625 Hz,both vertical and horizontal radiation coefficients are linearly proportional to the vibration frequency.When the vibration frequency is below 1000 Hz,the vertical radiation coefficient is smaller than the horizontal radiation coefficient,whereas at 1000 Hz and above,it is greater than the horizontal radiation coefficient.At above 1000 Hz,the vertical radiation coefficient has two peaks,occurring at approximately 2000 Hz and 5000 Hz.The vertical radiation coefficient has large values in a frequency range of 1500 Hz ~ 3000 Hz,thus the vertical vibration is the main contributor to the sound radiation and rail noises in this frequency range.The peak value of the vertical radiation coefficient around 5000 Hz is smaller than the one around 2000 Hz.The results of the BEM show that this method is suitable for predicting rail noises caused by rail vibration.