Analysis Of Combustion Noise Of Marine Diesel Engine Based On Fuel Injection Strategy

The rough working way of diesel engine makes combustion noise become a non-negligible and crucial leading part in the overall noise level.In this paper,the numerical simulation method is used to analyze the influence of different fuel injection strategies on the combustion noise of diesel engines based on the incylinder combustion process,and the relevant optimization is carried out.The main contents are as follows: First,a numerical simulation model describing the in-cylinder combustion process is established,the calculation grid is introduced,and the experimental results in related literature are compared;second,the generation mechanism of diesel engine transient combustion noise is analyzed.According to the in-cylinder combustion process,the evaluation index and calculation method of combustion noise are determined.Thirdly,the four injection strategies of main injection advance angle,pre-injection,pre-main injection interval and pre-injection amount are studied by the control variable method.The influence law of diesel engine combustion process and combustion noise.Finally,based on orthogonal test,the influence degree of each parameter of fuel injection strategy on combustion noise is studied,and the optimization is carried out with the reduction of in-cylinder sound pressure level as the main goal.Through the research of this paper,the feasibility of the numerical simulation method adopted in this paper is verified at first.The research shows that delaying the fuel injection time without pre-injection is beneficial to reduce the ignition delay period and the pressure rise rate,thereby reducing the average sound pressure level in the cylinder;adding pre-injection can better improve the incylinder combustion environment and optimize the combustion process reduces the level of combustion noise;the selection of the optimal pre-main injection interval is related to the speed and working conditions,and the appropriate premain injection interval setting can improve the main injection combustion and reduce noise radiation;the pre-injection amount accounts for The increase of the ratio increases the peak in-cylinder pressure,temperature and heat release rate,and makes the peak level of the pressure rise rate in the pre-injection stage higher than that in the main injection combustion stage,resulting in an increase in the incylinder pressure level.Through the orthogonal test design,the influence degree of each fuel injection parameter on the in-cylinder sound pressure level is obtained from large to small: pre-injection amount> main injection advance angle> premain injection interval> pre-injection duration> main injection duration;In addition,the optimization scheme obtained by the orthogonal design greatly improves the in-cylinder combustion process.Compared with the case where the original setting minimizes the in-cylinder sound pressure level,the optimized incylinder sound pressure level is reduced by 1.0% and the pressure is increased.The peak rate is reduced by 10.2%,while soot and NOx emissions are reduced by27% and 37%,respectively.The research work of this paper can provide some reference for the design of fuel injection strategy aiming at optimizing the combustion process of diesel engine and reducing combustion noise.