高斯叠代法研究相控阵非线性声场

Study of the acoustic nonlinear field generated from a phased array using Gaussian superposition technique

相控阵在聚焦超声治疗应用中不可避免地受到非线性影响,提出了采用高斯叠代法计算相控阵的非线性声场。在该方法中,利用预设焦点参数并应用伪逆矩阵算法得到阵元的激励参数;然后将阵元近似拟合成一组高斯声束的叠加,通过高斯声束叠代计算非线性声场。数值计算中以64阵元一维相控阵为研究对象;线性条件下,高斯叠代法结果与菲涅耳积分结果的误差低于0.5%,验证了该方法的可行性;单焦点及双焦点模式的相控阵非线性声场结果表明非线性效应能提高焦点聚焦性能,并且非线性效应与激励声压及激励频率成正比。

A numerical approach is developed to calculate the nonlinear sound field generated from a phased array based on the superposition technique of Gaussian beams.The parameters of the phased array elements are first estimated from the focal parameters using the inverse matrix algorithm;Then the elements are expressed as a set of Gaussian functions; Finally,the nonlinear sound field can be calculated using the superposition technique of Gaussian beams.A 64×1 phased array is performed in the numerical simulation.In the linear case,the difference between the results of the Gaussian superposition technique and the Fresnel integral is less than 0.5%,which verifies the feasibility of the approach.In the nonlinear case,the nonlinear fields of single-focus and double-focus modes are calculated.The results reveal that the nonlinear effects can improve the focusing performance,and the nonlinear effects are related with the source pressures and the excitation frequencies.