Prediction Analysis Of Cylinder Pressure Oscillation And Combustion Noise Of Marine Diesel Engine

Response to the current emission regulations of noise,the control of diesel engine noise has become an important research topic of diesel engine designer and manufactory,and combustion noise as the most important part of diesel engine noise has naturally attracted the research attention from scholars.Because of the high manufacturing cost of diesel engine,the noise emission performance optimization of diesel engine during the design stage can effectively reduce the cost.In this thesis,the combustion noise of diesel engine is predicted by simulation and verified by experiments.The specific research content is as follows:Firstly,the combustion simulation model of the diesel engine cylinder is established and compared with the experimental results,to correct the cylinder model and verify the accuracy.The combustion chamber data is obtained by the simulation model,by this established the acoustic model of the cylinder,and the resonant frequency zone of the diesel engine is obtained.The pressure graph and pressure curve are used to show the pressure oscillation inside the cylinder,and the calculation method of combustion noise is evaluated by pressure,and the prediction method of the post-body radiation noise of combustion noise is introduced.Then,changing the operation parameters of the diesel engine combustion model(including speed,compression ratio,injection advance angle,multiple injection and so on),by comparing the evaluation index of combustion noise,the influence of different parameters on the combustion noise change trend is determined,and the mechanism of the effect of multiple injection indicators on the combustion noise change is expounded according to the heat rate curve.It provides some design ideas for the combustion noise control of diesel engines.Finally,the noise and pressure measurement under the advance angle of a direct injection single-cylinder diesel engine is measured,the accuracy of the simulation results to predict the change trend is verified,and the correlation of pressure-noise data is calculated,and the combustion noise is mainly presented in the mid-band after the body radiation.Therefore,the noise reduction needs to mainly consider the combustion thermo acoustic resonance of the mid-frequency band.