直喷式柴油机瞬态工况燃烧噪声二级影响机理研究

研究直喷式柴油机瞬态工况燃烧噪声二级影响机理。设计瞬态与稳态工况燃烧噪声试验，测量燃烧噪声二级影响因素，分析瞬态工况下壁面温度、油管压力和针阀升程等间接因素影响动力负荷与压力高频振荡，从而影响燃烧噪声的二级影响机理，并对不同供油提前角瞬态工况燃烧噪声二级影响机理进行了研究。结果表明，瞬态工况壁面温度、油管压力、针阀升程及针阀开启时间均高于同负荷同转速的稳态工况，影响到瞬态工况滞燃期以及滞燃期的喷油量，进而影响动力负荷和压力高频振荡，使得瞬态与稳态工况燃烧噪声产生差异。

Secondary Influencing Factors of Combustion Noise Mechanism under Transient Conditions of DI Diesel Engine

The secondary influencing factors of combustion noise mechanism under transient conditions of DI Diesel engines were studied.The secondary influencing factors of combustion noise were measured under steady and transient conditions.Under the same load and engine speed,the secondary influencing factors of combustion noise was analyzed including combustion chamber wall's temperature,fuel injection pressure,needle lift between transient conditions and steady conditions.The difference of the secondary influencing factors under the two conditions affects the aerodynamic load,high-frequency oscillation and combustion noise between steady and transient conditions.The secondary influencing mechanism of combustion under transient conditions at different fuel delivery advance angles is also studied.The result shows that wall temperature of combustion chamber,fuel injection pressure,maximum of needle lift and opening duration of needle lift under transient conditions are higher than those under steady conditions in the same load and engine speed,resulting in the difference in ignition delay,starting point of combustion,and fuel injection quantity between transient and steady condition,influencing the aerodynamic load and high-frequency oscillation of combustion pressure,making the difference of combustion noise between the two conditions.