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内贴吸声材料的圆形、矩形等吸声管,作为使管内传播声音衰减的有效而简便方法,已在许多方面实际应用。为了从数值上求出声音的衰减和幅射,需要解吸声材料表面边界条件的本征值方程。解这个本征值方程的方法之一是归结微分方程的方法。本文对于吸声材料阻抗的大、小,分别进行了详细的分析。将其复数变数的一阶非线性微分方程,根据Cauchy-Riemann定理变换成4个实变数微分方程,用Runge-Kutta法,分别求解,并确定能得到本征值的方法。对j=1模,
Circular sound absorbing materials such as circular, rectangular sound absorption tube, as the tube to spread sound attenuation effective and simple method, has many practical applications. In order to numerically determine sound attenuation and radiation, it is necessary to desorb the eigenvalue equations for acoustic material surface boundary conditions. One way to solve this eigenvalue equation is to summarize the method of differential equations. In this paper, the impedance of sound-absorbing materials, large, small, were analyzed in detail. First-order nonlinear differential equations of complex variables are transformed into four real differential equations according to Cauchy-Riemann’s theorem. Runge-Kutta method is used to solve the equations respectively and the method to obtain the eigenvalues is obtained. For j = 1 mode,