Analysis Of The Noise Mechanism And Research On Sound Intensity Identification Of Diesel Engine

As reducing the noise of engine is the important content of improving the performance of engine and vehicle, it is significant to carry out the research on the noise mechanism and Sound Intensity Measurement Technique of Diesel Engine.This dissertation makes an exposition of the basic nature of noise and analyzes characteristics of the creation and transmission of sound; it classifies various noises of the diesel engine, and discusses the mechanism and spreading way of various engine noises under the analysis of the structural features and working principles of diesel engine; it puts emphasis on a theoretic research into producing mechanism, influencing factors and control measures of the aerodynamic noise, combustion noise, mechanical noise and surface radiation noise; moreover it makes a relevant experimental analysis of the intake and exhaust noise and surface radiation noiseThe dissertation works out a testing scheme of surface radiation noise of the diesel engine by using basic theories and methods of sound intensity measurement. The sound intensity measurement is carried out on the surface radiation noise of diesel engine in a semi-anechoic chamber. The author draws the sound intensity contour map of the diesel engine through the analysis of the results of the experiment, gets the noise distribution for the engine, and then locates the main parts of noise source of the diesel engine in deferent working conditions which mainly include the flywheel house, spray fuel pump, turbocharger and belt pulley. The dissertation also analyzes its noise radiation characteristic, calculates the acoustic power lever of the main noise source, and provides significant basis to reduce the engine's noise level.