条纹薄膜降低水下航行器流噪声的实验研究

Experimental Study on FlowNoise Reduction by Riblets

介绍了条纹薄膜降噪实验的原理、方法及结果，通过实验研究了不同形状和尺寸条纹的降噪效果，对优选的一种条纹（宽０．１ｍｍ的三角形条纹）薄膜进行了较深入的研究。实验结果表明条纹薄膜具有较明显的降噪效果，最大降噪量可达５ｄＢ左右。

Noise reduction has become more urgent in China now than ever before. As far as we can ascertain, there exists little published test data on flow noise reduction. We utilized the fairly well equiped NPU (Northwestern Polytechnical University) water tunnel to obtain a certain amount of such data. Out of several recently proposed methods, we selected the riblet method . The shape of riblet was shown in Fig.2. S in Fig.2 represented the width of riblet, and the angle of 59° was generally used in P.R.China. We used two values of riblet width S :0.06, 0.10 mm. The frequency range of noise was from 2 kHz to 50 kHz. Figs.3 and 4 gave test curves for water flow velocity of 7.86 and 9.94 m/s respectively. The three curves in either figure corresponded to: (1) no film used . (2) S =0.06mm, (3) S =0.1mm. Either figure was divided into three frequency ranges to make differences between three curves easily discernible. For both water flow velocities used, the maximum flow noise reduction, as can be seen from Figs. 3 and 4, was 5 dB when S =0.10 mm. In general flow noise reduction depended on water flow velocity, noise frequency, and riblet width.