流体动力性噪声的相似关系研究

Study of similarities for fluid-dynamic noise

以声学相似原理为依据,通过对流体动力噪声基本理论的研究分析,在建立水(气)动声学主要相似关系的基础上,研究了由于不满足雷诺数一致而可能导致的相似关系的破坏以及需要进行的相应修正。研究结果表明,尽管模型与实物的流体动力性噪声并不严格相似,但只要保证两者边界面流体的运动状态没有本质的区别,则从模型实验的结果推算实物的噪声性能是可行的,不过要对因雷诺数不同而引起的差异进行适当的修正。文中还以船舶螺旋桨为例,通过对模型和实桨对比实验结果的分析和计算,说明了尺度效应的基本特性。对于桨叶振动的影响以及当测试距离不满足相似关系时所需进行的修正等,本文也进行了初步的分析讨论。

Based on the principles of acoustic similarity, the main similar relationships of fluid-dynamic noise are studied by analyzing its basic theory and excitation mechanism, especially the necessary amendment while the Reynolds numbers of a model and a real one are not equal. The results show that it is feasible to calculate the acoustic properties of a real object from the outcome of model test, while the moving states of fluid on surfaces of model and real one are not essentially distinctive, although their fluid-dynamically acoustic similarity is not exact. Then an appropriate correction according to the difference between their Reynolds numbers is needed. As an example, the results of model test of ship propellers were analyzed and calculated to show the main characteristics of scale effect. The amendments when the measuring distances do not meet the similar relations and the influences of propeller leaves' vibration are discussed as well.