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应用Lighthill的气动声学理论对气流绕过圆柱产生气动噪声的机理进行实验研究,设计和建立了低噪声、低湍流度的模型风洞,其实验段截面为1OOmm×100mm,气流核心区的湍流度低于0.4%。对风啸声的气动声学理论进行了局部性的验证,并对相关测量技术进行了研究。实验表明,雷诺数在4×10~3～1×10~4的范围内,空间相关长度 l_c/d 在3.7左右,相关系数曲线下面积的重心矩γ/d为1.3,基本上保持不变。应用热线风速仪和 B ＆ K 声级计同时测量了圆柱绕流的流场和声场。从流速和声压的自功率谱以及它们的互功率谱研究表明,这三种方法确定的 Strouhal 数是一致的。雷诺数在6×10~3到1.8×10~4范围内,Strouhal 数为0.192。结果说明了圆柱的脱落旋涡和风啸声之间存在着内在的联系。
The aerodynamic acoustics theory of Lighthill was used to study the mechanism of the aerodynamic noise generated by the air around the cylinder. The model wind tunnel with low noise and low turbulence was designed and established. The experimental section was 100 mm × 100 mm. The turbulence Below 0.4%. The aerodynamic acoustics theory of wind howling was verified locally, and related measurement techniques were studied. Experiments show that the Reynolds number is in the range of 4 × 10 ~ 3 ~ 1 × 10 ~ 4, the spatial correlation length l_c / d is about 3.7, and the centroid moment γ / d of the area under the correlation coefficient curve is 1.3, which is basically unchanged . The flow field and the sound field around the cylinder were measured simultaneously with the hotline anemometer and the B & K sound level meter. The self-power spectra of velocity and sound pressure and their cross-power spectra show that the Strouhal numbers determined by these three methods are consistent. Reynolds number in the range of 6 × 10 ~ 3 to 1.8 × 10 ~ 4, Strouhal number is 0.192. The results show that there is an intrinsic relationship between the cylinder shedding vortex and the wind whistling noise.