Separation of Tonal and Broadband Noise Components by Cyclostationary Analysis of the Modal Sound Field in a Low-Speed Fan Test Rig

Abstract

The radial mode analysis is a well-established method used to analyze the tonal and broadband components of in-duct sound fields radiated from axial turbomachinery. Based on the cyclostationary analysis, a separation procedure is presented in order to obtain the signals associated with the tonal and broadband sound fields separately. The analysis of experimental data shows that the sound power and the mode coherences of the respective sound field components are identified exactly. Furthermore, the cyclostationary analysis is used to track the development of the sound power as a function of the rotor rotation angle at the blade passing frequencies, exemplarily.