Method for the analysis of sound sources in rotating systems

旋转机械部件往往是产生噪音的重要原因。因此，许多控制噪声的努力都集中在这些部分的噪声控制措施上。旋转系统中声音产生的实验分析往往退回到非旋转系统中的分析。例如，在风洞中只分析风扇的一个叶片，而不是整个风扇。这种检验的结论不能总是转移到旋转系统中可以找到的条件。在某些情况下(例如电动马达)，这样的程序本质上是不可能的。因此，该项目旨在为分析和更好地了解旋转系统中的声音产生作出相当大的贡献。这应该通过开发一种新的实验方法来实现，该方法允许详细和可靠地测量转子处的声音产生的位置、种类和强度。该方法的基础是使用固定的、不旋转的麦克风阵列进行测量。使用适当的信号处理，阵列虚拟地与声源一起旋转，并使用各种声源和声音传播模型，通过计算方法估计旋转声源的特性。该项目的关键是检查哪些模型和方法能够产生可靠的结果。为此，使用蒙特卡罗方法和各种合成测试数据集来实现和分析各种模型和方法。此外，通过两个实验室实验对实际应用进行了测试。AIMS项目的重要性是因为有可能对旋转系统中声音产生的假设、模型预测或数值计算进行更详细的测试，就像今天所可能的那样。这使得能够在源头上采取更集中的噪声控制措施。

Rotating machinery parts are often significant causes of noise. Accordingly, many efforts to control noise focus on noise control measures on these parts. The experimental analysis of sound generation in rotating systems often falls back to an analysis in the non-rotating system. For example, instead of a whole fan just one blade of a fan is analyzed in a wind tunnel. The conclusions from such examination cannot always be transfered to the conditions that can be found in rotating system. In some cases (for example an electric motor) such procedure is inherently impossible. Thus, the project aims at a considerable contribution to the analysis and the improved understanding of the sound generation in rotating systems. This should be accomplished by developing a new experimental method allowing detailed and reliable measurements of location, kind and strength of sound generation at rotors. Basis of the method is a measurement using a fixed, non-rotating microphone array. Using appropriate signal processing, the array is virtually rotated with the source and using various sound source and sound propagation models the properties of the rotating sound sources are estimated by a calculation method. Essential to the project is the examination of which models and methods yield reliable results. To this end various models and methods are implemented and analyzed using a Monte-Carlo-approach and various sets of synthesized test data sets. Additionally, the practical application is tested using two laboratory experiments. The importance of the project aims results from the possibility to test hypotheses, model predictions or numerical calculations of sound generation in rotating systems with much greater detail as it is possible today. This enables more focus noise control measures at the source.