Airworthiness Assessment Of Combustor Noise Of Civil Aircraft Engine

On February 14, 2013, the committee on aviation environmental protection of ICAO passed the latest airworthiness standards of aircraft noise. New standard required that the total noise level should be 7dB lower than the current standard, which will take effect in2017 for reducing the noise level further. However, one of the main noise level of the aviation aircraft is the engine noise in current, one of the main noise level of the engine is the combustor noise. So building a combustor noise assessment platform of the aviation aircraft has great significance for the airworthiness assessment of China. Assessing the combustor noise contribution before the research of the engine can effectively reduce the cost of measuring the combustor noise. In the meantime, it can provide combustor noise data for the researchers and it is helpful for our country to get rid of the restrictions on the research of the civil aircraft engine noise.In this paper, firstly, it researches the airworthiness standard of the aircraft noise,introduces three methods for assessing the combustor noise of the engine, which are SAE method, small engine method and narrowband method, establishes the combustor noise assessment platform based on the three methods through MATLAB GUI, which can compute the sound pressure level SPL, dBA and EPNL between 1m and 10 km distance,uses the three methods to assess one engine and compares the results of the three methods and the engine static test data to verify the reliability and accuracy of the model.Then, according to the assessment data, it analyzes the characteristic of the combustor noise, reveals the regular pattern that the combustor noise varies with the change of the directivity, frequency, the low pressure turbine rotating speed and the distance, researches the contribution of combustor noise for the engine noise in three stage(sideline, flyover and approach), calculates and draws the noise contour line. Finally, it considers the sound attenuation effect of atmosphere and the type of noise for assessing the result, then carries out the airworthiness assessment of the engine combustor noise, which provides a reference for the development and airworthiness of the engine in China.