Research On The Prediction Method Of Static Noise Data Of Turbofan Core Engine

According to the suggestion of the ninth meeting of the committee on aviation environmental protection of ICAO: new aeroplane types submitted for certification on or after 31 December 2017,and on or after 31 December 2020 for aircraft less than 55 tons in weight would be required that the total noise level should be 7EPNdB lower than the current standard.And one of the main noise source of the aviation aircraft is the engine noise,and with the turbofan design trends and its higher and higher by-pass ratio,the reduction of fan pressure ratio and the reduction of fan-tip speed,and the use of acoustic form of fan,thus reducing the noise level of jet and fan.However,with the increase of overall pressure ratio and the combustor exit temperature,the core engine noise level is greatly enhanced,and to a certain extent,surpasses fan and jet noise level.So to analyze the turbofan core engine noise is important,especially after the assembly of our C919 aircraft,our CJ-1000 A is on the process to develop,so we need to do the noise assessment in the beginning,thus reducing our research cost.In this paper,firstly I introduce the methods to assess the turbofan combustor and turbine noise,then I choose the three methods with high accuracy,they are: SAE method,Peart &Dunn method and Smith & Bushell method.And I do the combustor noise assessment of turbofan CF34-10 A with SAE method,besides I do the core engine noise assessment of turbofans DGEN 380 and CFM56-7B with SAE method,Peart & Dunn method and Smith &Bushell method.By the construction of the models for the combustor and turbine noise assessment,I analyze the noise properties of the combustor noise and turbine noise,and in use of the measured static noise data of CF34-10 A and CFM56-7B given by GE to compare with the predicted noise,I verify the accuracy of our models.And then,I combine the CFM56-7B and DGEN 380's combustor and turbine noise together to get the core noise,analyzing its properties and the influence of “Doppler fator”,in the meantime,I analyze also the weight of core noise of CFM56-7B in all the engine parts and the total engine noise,by doing so I analyze the influence of the parameter turbine diameter on the core noise,thus providing reference for the development and airworthiness of our big engine CJ-1000 A,which is a rival engine of CFM56-7B.Finally,I disscuss the influence of core engine parameters on the corenoise: the combustor entrance total pressure,the turbine diameter,the turbine stages,the entrance temperature of turbine and the temperature drop across turbine.