| At present,China has made some achievements in the independent research and development of civil aviation,especially after the successful test flight of the large aircraft C919,which proves that China's development in the civil aviation industry is getting better and better.In order to obtain the airworthiness certification,all aspects of the measurement must meet the requirements of civil aviation regulations,which stipulate the noise for the whole aircraft.With the decrease of jet noise,people pay more and more attention to combustion noise.However,combustion noise can't be directly obtained through experiments,so it becomes particularly important to study combustion noise through prediction.The study of combustion noise in flight can provide a powerful basis for airworthiness assessment,however,there are few researches on time domain.This paper introduces the basic knowledge of noise and the mechanism of combustor noise.In this paper,SAE model is firstly established in Matlab,then its accuracy is verified in static state,and finally it is applied in flight state.Specifically,the angle and distance parameters obtained from the track calculation,as well as the correction factors to be considered,are input into the model to obtain the sound pressure level.The prediction of time-domain signal is to take a measuring point every 0.5s on the obtained track for prediction,and obtain the relevant data of combustion noise in the time-domain,such as the total sound pressure level.The change of combustion noise with time in each flight state was analyzed,and the effective sensible noise level and the noise level limit data of the fifth stage in each state were compared,and then concluded that the engine in the study meets the airworthiness approval after being installed on the aircraft.Using SAE algorithm to predict combustor noise can further enrich the database and provide more reference information for airworthiness examination. |
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