Theoretical And Experimental Study On Oxygen-enriched Combustion In Gasoline Engine

The crisis of petroleum,combined with the desire to reduce the pollutant effects of combustion have led to a finding ways to increase the efficiency,of the engine combustion process.Thus,the latest research by experts and institutions around the world is being driven towards ways to improve power,improve combustion performance and reduce pollution from the engine.Aimed at characteristic of engine combustion,the thesis discusses oxygen-enriched combustion technique and the effect of oxygen in combustion.A turbulent propagation model for oxygen-enriched combustion flame is proposed,considering the combustion flame propagation velocity.Series of gasoline experimentation are carried out,based on the theoretic discuss,to validate the combustion model and the effect of oxygen in combustion.The technique of oxygen-enriched combustion and the effect mechanism of oxygen are proposed,regard to the air entering cylinder.Combustion and emission characteristics of the engine are studied under the condition of engine worked with different componential air,which were based on the effect mechanism of oxygen,then to explore the measurements of how to improve the combustion characteristic and the power-output ability of engine.According to the single-cylinder earbureted gasoline engine Honda G200,semi-physical simulation model of engine combustion are proposed,including quasi-dimensional diagnosis model,forecast model,calculation model of physical parameters for gas,heat transfer submodel in cylinder,etc.,to forecast the combustion characteristics under different engine operating conditions.Considering the combustion flame propagation velocity,a turbulent propagation model for oxygen-enriched combustion flame is proposed.As one of the influence factors of engine combustion,oxygen concentration in the air entering the cylinder is proposed to describe the gasoline combustion velocity and flame propagation characteristics,as well as the influences of different oxygen concentration on the engine cornbustion characteristics are studied too,results indicate that as the oxygen concentration enriches,flame propagation velocity is enhanced, mass burning rate increases,and the average temperature and pressure in cylinder increase too, the ability to work of engine is enhanced.Based on the chemic balance theory of combustion,ratio of air to fuel and some other parameters,such as heat value,temperature,and products of combustion,are studied.Using the calculation theory of engine work characteristic,influence of oxygen concentration on combustion characteristics and power is studied,the emission of engine is studied too.According to the experimental single-cylinder carbureted gasoline engine Honda G200, combustion chamber geometry is measured by three coordinate measuring machine,and a combustion chamber model is proposed by node integral,method.Boundary conditions are confirmed,the characteristics of flame propagation in combustion process and some parameters,such as burned volume,are calculated to analyze combustion model of engine.An experiment is performed on a single-cylinder carbureted gasoline engine Honda G200, to study the dynamical performance,combustion performance and emission perfonmance of engine.Cycle variation of combustion is studied,using cylinder pressure.