【作者】 张家雨；

【导师】 舒歌群；

【作者基本信息】 天津大学 ， 动力机械及工程， 2007， 硕士

【摘要】 直喷式柴油机燃烧噪声对整机噪声的贡献占有重要地位,而工况的瞬态变化首先反映的是内燃机工作过程的变化。因此,对内燃机在瞬态工况下噪声的剧烈变化现象的研究中,瞬态工况对内燃机燃烧噪声的影响机理是必须加以解决的问题。本文以涡轮增压直喷式柴油机作为研究对象,开展瞬态工况燃烧噪声测试技术和测试方法研究,通过近场声压法测量噪声并设计时间窗获取燃烧噪声,同时测量了缸内压力、油管嘴端压力和振动信号,从影响燃烧噪声的直接因素——气体动力载荷和缸内压力高频振荡两个方面——分析了瞬态和稳态工况下燃烧噪声产生差异的原因。研究发现,压力升高率和缸内压力高频振荡是影响燃烧噪声的主要因素。通过分析燃烧噪声的间接影响因素(滞燃期、喷油量等)在瞬态与稳态工况下的差异,研究了这些间接影响因素是如何影响瞬态与稳态工况下的气缸压力的激励特性和缸内压力高频振荡,并进一步影响燃烧噪声的。研究结果表明,同负荷同转速下的瞬态与稳态工况的滞燃期、喷油量、壁面温度等参数的差异,引起燃烧压力、压力升高率和高频压力振荡频率和幅值发生变化,使得瞬态工况与稳态工况燃烧噪声产生差异。更多还原

【Abstract】 The combustion noise plays an important role in the whole noise of the direct injection diesel engine. The transient change of conditions firstly reflects the change of the in-cylinder process of the internal combustion engine. In order to study the phenomena that the noise changes acutely in transient conditions, it is necessary to find out the effect mechanism of the transient conditions on combustion noise.This dissertation takes a turbocharged direct injection diesel engine as its research object, applying testing technology and testing method to the research on the combustion noise in transient conditions. It measures the noise through the method of near-field sound pressure and obtains combustion noise by way of designing time window. Meanwhile it measures the cylinder pressure, the pressure of nozzle end and the vibration signal. It analyzes the cause of the differences in combustion noise in transient conditions and stable conditions respectively through two direct factors which influence the combustion noise: the Aerodynamic load and the high-frequency oscillation of cylinder pressure. It shows that the rate of pressure rise and the high-frequency oscillation of cylinder pressure are the main factors which influence the combustion noise.The combustion delay period, the quantity of fuel injected, and so on are indirect influencing factors of the combustion noise. This dissertation analyzes that how these factors vary in transient condition and stable condition respectively. Thought that, this dissertation then researches how these factors influence the stimulus property of the cylinder pressure and the high-frequency oscillation of the cylinder pressure, and how they further influence the combustion noise in transient and stable condition respectively.The research shows that differences in parameter such as the combustion delay period, the quantity of fuel injected, the temperature of chamber wall in transient and stable conditions in the same load and rotation speed respectively result in the change of combustion pressure, the rate of pressure rise, the frequency and amplitude of the high-frequency oscillation of cylinder pressure, therefore result in different combustion noise in transient and stable conditions respectively.更多还原