水下吸声覆盖层声管测试的背衬研究

Effect of backing in the measurement of underwater anechoic coating with an acoustic cylindrical tube

在吸声覆盖层水声声管测试的实验研究中,覆盖层背衬的选择对测量结果有重大影响。在我们二维理论研究的基础上,建立了吸声覆盖层声学特性的传递函数模犁,分析比较了不同背衬对吸声覆盖层声学性能的影响。结果表明,不同背衬对吸声覆盖层吸声性能的影响具有明显不同的特性。背衬为双层壳体时,水层对吸声覆盖层的吸声系数曲线有明显的调制现象。背衬为单层壳体或双层壳体时,从整体上讲,吸声系数更趋近于刚性背衬而非软背衬的情况。在实验室小样品声管测试中,以较厚的钢柱作为背衬的测试数据来衡量吸声覆盖层性能更为合适,且易于实现。

Based on our two-dimensional approximate theoretical analysis, a transfer function model of the acoustic characteristics of underwater anechoic coating with various backings is established on the low-frequency range. The influences of various backings on acoustic performance of anechoic coating are analyzed and compared. The results show that the influences of various backings on the acoustic characteristics of anechoic coating are obviously different. When the backing is a double-shell, the water layer causes obvious modulation phenomenon to the absorption coefficient curve. Whether the backing is a single-shell or a double-shell, the absorption performance approaches more closely to that with a rigid backing. In the measurement of small sample in an acoustic cylindrical tube, measurement data with rigid backing should be taken as the standard of the performance of an anechoic coating.