To reduce aircraft engine noise ,a measurement technique is urgently needed for broadband noise determination inside the turbomachinery duct to guide noise reduction design .In this paper ,results of the sound power propagating up-stream and downstream are determined with cross-correlation analysis of sound pressure .The microphone arrays installed upstream of the fan rig consist of 2 axial arrays with circumferential interval of 180° ,with each array having 14 equidistant microphones .Arrays are installed on a rotating duct .In the experiment ,the duct rotates once per 6° ,and the sound pressure data of 840 positions in total are acquired .The incident sound waves can be as much as 10 dB higher than the reflected sound waves .The decomposed modal results show that rotor-stator interaction modes are the dominant modes at blade pass-ing frequency and its harmonics .The decomposed results are consistent when different sensors are used as reference signals and thus this experimental method is not sensitive to the reference signal position ,showing good applicability of the method .%航空发动机降噪研究迫切需要一种叶轮机械管道内宽频噪声测量方法来指导降噪设计.本文通过对阵列测量的声压信号进行互相关分析,得到管道内顺流和逆流传播的模态声功率结果.安装在风扇实验台进口段的传声器阵列由2排周向间隔180°的轴向阵列组成,每排阵列有14个等间距的传声器.阵列安装在可周向旋转的测量段上,实验中测量段每隔6°旋转一次,共获得840个测点位置的声场信号.结果表明入射波与反射波最大可相差10 dB.模态分解结果表明,转静干涉模态是转子通过频率及其谐频处的主导模态.利用不同参考信号计算出的声场结果相同,说明该实验测试方法对参考信号位置没有特殊要求,进一步说明该方法有很好的适用性.
展开▼
