Research On Separation Method Of Civil Aircraft Core Engine Noise

With the rapid development of China's aviation economy, the engine noise reduction problem becomes very important. Since the promulgation of Federal Aviation Regulations Section 36 started, the civil aircraft noise emissions have been regarded as one of the important indexes to obtain airworthiness certification of aircraft. At the same time, with the development of the aviation industry, the emissions of jet noise and fan noise have been greatly decreased, the importance of the core noise is highlighted. The experiment data which can be measured directly is the total engine noise spectrum, and we cannot obtain the components noise by direct experimental measurements. It greatly affects the work of the exploration process of engine noise. Therefore, a method which can separate the core noise from the engine noise is in urgent need to be developed.At present, the domestic study on core engine noise is still in the basic stage. Through the in-depth study of a large number of foreign documents, this paper summarizes three separation algorithm based on the measured noise at each microphone and autocorrelation and cross-correlation relationship, which are Parthasarathy method, Miles method and Ahuja method.. The research mainly divided into five parts, the significance of topics and research background, the acoustic basic and core noise mechanism, the algorithm model for the core noise separation, the realization of the algorithm based on MATLAB, and the analysis and visualization of numerical results. Based on these three core noise separation algorithm models, this paper will use the engineering software Matlab to complete the algorithm calculation, obtain the corresponding results, and the visualization of results. With the calculation results being further analyzed, this paper will obtain the changes of core machine noise sound pressure level with the engine rotation rate, measuring angle and frequency, have a more in-depth understanding of the nature of core noise.Through the comparison of the calculation results and the core noise value provided by the engine manufacturer, the algorithms are verified the validity and rationality. It will provide the reference for the validation of our current civil aviation engine research and development and airworthiness provisions.