直喷式柴油机瞬态工况燃烧噪声的试验研究与分析

Experimental Study and Analysis of Combustion Noise in DI-Diesel Engine under Transient Conditions

研究直喷式柴油机瞬态工况对燃烧噪声影响机理。开展内燃机瞬态工况测试技术和测试方法研究,找出瞬态工况下燃烧噪声相对于同转速、同负荷的稳态工况燃烧噪声差异的规律,并从瞬态与稳态工况下燃烧过程的差异对试验结果进行分析。瞬态工况壁面温度、喷油压力、针阀升程最大值和针阀开启持续时间均高于同负荷同转速的稳态工况,导致瞬态工况滞燃期、燃烧始点和喷油量与稳态工况相比产生差异。结果表明,瞬态工况下动力负荷和压力高频振荡相对于同负荷同转速的稳态工况发生改变是引起燃烧噪声产生差异的根本原因。

This paper studies the influencing mechanisms of combustion noise in DI-Diesel engines under transient conditions, and investigates the testing methods under transient conditions. The reason for the difference in combustion noise between transient conditions and steady conditions at the sanle load and engine speed is clarified. The results show that there exist the differences in ignition delay, starting point of combustion and fuel injection amount between transient conditions and steady conditions. These would be due to the large values in combustion chamber wall＇s temperature, fuel injection pressure, maximum needle lift and lift duration under transient conditions rather than under steady conditions at same load and speed. The result shows that the aerodynamic load and high-frequency oscillation of combustion pressure result in their differences in combustion noise.