Research On The Noise Identification Methods Of Aero Engine Turbine

With the rapid development of civil aviation, the aircraft and engine noise has become a topic of concern. The noise compliance with the requirement is one of the key factors in obtaining airworthiness certificate. It is quite important to research and product the civil aircraft and engine which meet the airworthiness standards, other than enhancing the airline's strength during the development of the civil aviation. The domestic high bypass ratio turbofan engines for civil projects has just started, the engine component noise are more cutting-edge research. By studying the noise of the engine components, the distribution and characteristics of noise of the various components can be determined, which is conducive to future noise reduction and airworthiness certification work.In the early turbojet and low bypass ratio turbofan engine, the turbine noise is less studied since it is not significant. With the increase of bypass ratio, the fan and jet noise is significantly reduced while the turbine noise rises. The turbine noise has become an important source during the approach phase.Two categories of turbine noise identification methods are researched and presented in this paper: the Beam Forming and Deconvolution Approach for the Mapping of Acoustic Sources(DAMAS) which using the sound field radiation information, and the 7 Microphones Method using the auto and cross spectra. The noise test data requirements and detailed steps of the two categories of methods are presented in this paper. With noise test data of GE Company, the identification of turbine noise is performed with the Beam Forming and DAMAS. The results are the sound pressure distribution at the polar arc of 45.72 m with different frequencies,angles and working states.To analyze the accuracy of the turbine noise identification, the Smith and Bushell model is selected to predict turbine noise. The comparison of overall sound pressurelevel, directivity and frequency distribution between the identification and prediction results is performed.Finally, an outlook of the turbine noise identification is made. This might be a reference for our ongoing civil aviation engine development and airworthiness research.