尚建华,张明敏.柱面波分解测量反射系数的一些分析[J].声学技术,2007,(5):860~865 |
柱面波分解测量反射系数的一些分析 |
Research on measuring reflection coefficients using cylindrical-wave decomposition |
投稿时间:2006-05-06 修订日期:2006-09-22 |
DOI: |
中文关键词: 声全息 任意入射角 反射系数 柱面波分解 数值模拟 测量误差 |
英文关键词: acoustic holography arbitrary angles of incidence reflection coefficients cylindrical-wave decomposition metrical error |
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中文摘要: |
论述了对于用声全息反演法测量水声材料任意入射角的反射系数,用柱面波分解比平面波分解优越的理由,平面波分解计算采用快速傅立叶变换受到波数域的分辨率及声波波长的限制,不能测量到任意入射角的反射系数;而柱面波分解理论则无上述限制,能测量任意入射角的反射系数,柱面波分解法利用了声源及测试材料声反射面的轴对称性,只需测量半径方向上的复声压数据,极大地减少了工作量。随后以水中8毫米厚的铝板为例,通过数值模拟,分析了测量过程中各种因素对测量精度的影响,这些因素包括测量半径、阵元及阵位置误差、阵元间隔、测量面高度的定位误差等,指出了实际测量过程中对这些因素均有很高的要求,低频条件下声源若不满足指向性很高的要求,测量大入射角的反射系数仍然存在困难。 |
英文摘要: |
With respect to the acoustical holographic technique for measuring reflection coefficients at arbitrary angles of incidence,a point of view was brought forward that using cylindrical-wave decomposition is superior to plane-wave decomposition. The plane-wave decomposition applying Fast Fourier Transform (FFT) can′t measure the reflection coefficients at arbitrary angles of incidence due to the restriction of wave number domain resolution and sound wavelength,however,the cylindrical-wave decomposition can do it without the limit. Besides,the method using cylindrical-wave decomposition can reduce workload tremendously by making use of the sound source and test material′s symmetry. Taking a numerical example of underwater 8 millimeters thick aluminum plate,the influences of various metrical factors were analyzed. These factors included radius of measurement area,inaccurate positions of the sensors and the array,sen-sor intervals and the location error of measurement-plane′s height. It is concluded that very high request to these factors should be satisfied in practical measurements,and it is difficult to measure the lower-frequency reflection coefficients at large incidence angles if the sound transmitter′s directivity is not high enough to meet the demand. |
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