【摘要】 通过频域有限差分法求解KZK方程,对吸收媒质中Gauss聚焦超声换能器的基波和高次谐波声场进行计算和仿真,研究了各次谐波沿传播方向的分布规律,发现高次谐波声场同样具有Gauss聚焦特性,并且谐波阶次越高,聚焦特性越好.此后讨论了不同的吸收系数对Gauss声场聚焦特性的影响,结果显示吸收系数的改变不会影响Gauss声场的径向分布形状,但吸收系数的增加导致聚焦区域声场强度的减弱,甚至聚焦无法实现.更多还原

【Abstract】 The fundamental and higher-order harmonic acoustic fields of a focused Gaussian ultrasonic transducer in absorbing medium were computed and simulated by solving the KZK equation using a frequency domain finite difference method.The distribution of every harmonic component along the propagation direction was investigated.The result indicates that these harmonic fields are also focused Gaussian beams and that the focused property of the harmonic field improves with the increase of harmonic order.Variant absorption coefficient’s influence on the focused property of the field was analyzed,and result shows that the variation of absorption coefficient does not influence the radial shape of the beam,but the increase of the absorption coefficient results in the attenuation of field intensity,rendering focusing an impossibility.更多还原