Analysis of Advanced Open Rotor Noise Measurements

摘要

This paper presents an analysis of the acoustic data collected during a series of tests of a model-scale advanced open rotor installed within the DNW low-speed wind tunnel. There is an overview of the tests and a description of the computational, numerical and analytical methods for predicting both tone and broadband noise levels of advanced open rotors. The measured data is discussed and assessed via comparisons with predictions and through analyses of tone radiation efficiencies. Comparisons between predictions and measured data are analysed in terms of the narrowband and one third octave noise levels, and in terms of both the tonal and the broadband contributions. It is shown that fast, analytical prediction methods are sufficiently accurate for both rotor-alone and interaction tones provided that the required inputs are obtained from a high-fidelity steady aerodynamic calculation. The effects of centerbody scattering and operation at angle of attack on measurements and predictions are also investigated. The paper concludes with a discussion of broadband noise showing, first, that broadband noise dominates the sound field at mid to high frequencies and, second, that there is some disagreement between current low-fidelity analytical methods for broadband noise and the measured broadband noise levels.