不同顶端形态声屏障菲涅尔半波带衍射研究

Study on Diffraction of Different Top Shaped Noise Barriers with Fresnel Half-wave Zone Method

为了研究不同顶端形态声屏障对噪声衍射的衰减特性,针对4种常见的声屏障噪声衰减问题,应用菲涅尔半波带法,对其插入损失进行计算并对其降噪效果进行评价。充分考虑次级扰动带来的半波带声能贡献,推导任意阶半波带声屏障声影区的衍射衰减计算公式。通过计算4种不同顶端形态下声屏障的插入损失,绘制不同声屏障下交通噪声的衍射声场,并呈现其水平和垂直方向的噪声衍射规律。计算结果表明,声屏障的插入损失随着高度和离声屏障距离的增加而减小。顶端形态对声屏障降噪效果有很大影响,其中T型和Y型屏障对声音遮挡最为明显,其次为折角型屏障,竖直型屏障降噪效果最差。试验结果验证了4种声屏障的衍射规律,并进一步证实了存在双衍射现象的T型和Y型屏障有更明显的降噪效果。

In order to study the noise diffraction attenuation characteristics of noise barriers with different top shapes,the noise attenuations of 4 common noise barriers are taken as the main object. Fresnel half-wave zone method is used to calculate the insertion loss and evaluate the denoise effect. Considering the noise energy contribution caused by secondary disturbance,the calculation formula of noise diffraction attenuation of arbitrary step half-wave zone in the shadow area is derived. By calculating the insertion losses of noise barrier with 4 top shapes,the acoustic diffraction field of traffic noise at different barriers are drawn,and the noise diffraction rules in horizontal and vertical directions are presented. The calculation result shows that（ 1） the insertion losses of the noise barriers decrease as the heights and distances to barriers adding;（ 2） the top shape has a strong effect on denoise effect of the barrier,among which the T-shaped and Y-shaped barriers present the most obvious noise shielding,then the angle-shaped barrier,and the upright barrier is at last. The diffraction rules of the 4 noise barriers are verified by the experiment,and it is confirmed that noise abatement is more obvious behind the T-shaped and Y-shaped barriers which have twice diffractions.