Airworthiness Assessment For Forward-radiated Fan Noise Of Civil Aircraft Engine Based On Heidmann Module

In this paper, some basics about civil aircraft engine noise are introduced firstly,including physical metrics and subjective metrics, engine noise static test and engine component noise separation. Then, prediction assumptions and mechanisms of forward-radiated fan noise of the civil aircraft engine are explained. The prediction algorithms for forward-radiated fan noise of the civil aircraft engine are compared between each other and are analyzed including the original Heidmann module and the two modified modules. With Matlab GUI(Graphical User Interface) function, a software for the airworthiness assessments of the forward-radiated fan noise is built.Then, by using this software, compare the predicted results by the three modules with the test data, the proper module is determined to predict the forward-radiated fan noise for the high bypass ratio engine. The influences on the forward-radiated fan noise by the direction and frequency are analyzed through comparing the SPL errors varying with different direction, analyzing the annoyance level varying with different frequencies, the perceived noise level and tone corrected perceived noise level based on the predicted results and static data.Then using the built prediction module, airworthiness assessment for the forward-radiated fan noise to certain engine is conducted by the following aspects:firstly, draw specific noise level contour to analyze the effect range; secondly, analyze the contribution of the forward-radiated fan noise to the engine noise and relation between the contribution variation and the direction and rotating speed; thirdly, study the effects of the numbers and the axial distance of the blades and vanes on the forward-radiated fan noise. All these aspects are important for the control of the forward-radiated fan noise in the design and development.