考虑相位的屏障衍射声场工程算法研究

Engineering algorithm research of barrier diffraction acoustic field concerning the phase

目前声屏障衰减的工程算法均基于能量法,不考虑声源在衍射时的相位变化,而在计算有限长屏障衍射声场或多个屏障的多重衍射声场时,往往误差较大。因此,提出了一种考虑相位、用于计算屏障声衍射的新工程计算方法,该工程算法基于Keller的几何声衍射理论,且延伸自Pierce提出的一个刚性楔形体边界的Hadden-Pierce严格解,相比严格解的积分算法,该简化算法能在计算声影边界的衍射声时避免奇异,计算效率高。使用本文提出的算法、边界元法和Wadsworth研究的实验数据对三维有限长薄屏障和单个厚屏障的双重衍射声场进行了计算,结果表明,该算法与Hadden-Pierce原始积分算法误差在0.5 d B范围以内,与边界元法误差在2 d B以内,且与Wadsworth实验数据吻合度较高;而在计算效率方面,本算法相比原始积分算法提高了500多倍,比边界元法提高了约2 400倍,说明本简化算法完全可应用于户外噪声传播中屏障衰减的准确计算。

The engineering algorithms of barrier attenuation are now always based on the energy method,ignoring the phase change of the sound source diffraction,and resulting in larger error when calculating the finite length barrier diffraction acoustic field or multiple diffraction acoustic field of the multiple barrier. We propose a new engineering calculation method which is based on Keller ＇s geometrical theory of diffraction and extends Pierce＇s Hadden-Pierce rigorous solution to calculate the barrier sound diffraction considering the phase. It can avoid the singularity and improve the calculation efficiency when it calculating the sound diffraction of acoustic shadow boundary comparing with the integral algorithm in the rigorous solution. We make a calculation of the double diffraction acoustic field of three-dimensional finite length barrier and a single thick barrier using the proposed algorithm,the boundary element method and Wadswort＇s experimental data respectively. The results show that the error between the proposed algorithm and Hadden-Pierce original integral algorithm is within 0. 5 d B,2d B in the boundary element method,and nearly the same with the Wadswort＇s experimental data. Besides,in terms of computational efficiency,the proposed algorithm raised more than 500 times comparing with the original integral algorithm and about 2 400 times with the boundary element method. The experiment proved that the new simplified algorithm can be completely applied to the accurate calculation of the barrier attenuation in the outdoor noise propagation.