【作者】 熊伟；

【导师】 刘会猛；

【作者基本信息】 华中科技大学 ， 动力机械及工程， 2009， 硕士

【摘要】 船舶柴油机使用低质燃油的目的是为了合理地利用石油资源和降低营运成本。而低质油的物理化学性质较普通轻质柴油而言要差得多。因此在使用低质燃油前,对其进行预处理是很有必要的,预热就是其中一项有效的措施。内河航运使用的柴油机缸径更小、转速更快,燃用的物性更差的低质燃油时,组织好其喷雾过程显得更为重要。雾化质量的好坏决定了可燃混合气的形成质量,进而影响到燃烧,最终将影响内燃机的动力性、经济性和排放水平。因此组织好燃油的喷雾,将对内燃机的各项指标起着决定性作用。文中在综合分析目前研究发动机燃油喷射雾化机理和研究成果的基础上,建立了合适的数学物理模型。对20号重柴油的喷雾过程进行了多维数值模拟研究。认为空穴流对雾化的进行起了至关重要的作用,而考虑到水力倒流在实际中不可能发生。因此,通过改变喷嘴的几何结构以控制喷孔内流动状态,研究了在单向流和空穴流情况下的喷雾过程。计算20号重柴油的与喷雾相关的物性参数随温度的改变值。研究了在不同启喷压力、喷孔直径和燃油预热温度下20号重柴油的喷雾。研究表明,空穴流对喷雾有着积极的作用。相比单相流,在空穴流状态下,喷雾可以获得更大的喷雾贯穿距,更小的索特平均直径。提高喷射压力改善了喷雾质量,提高了喷雾贯穿距,降低了索特平均直径。预热燃油对喷雾起到了积极作用,提高20号重柴油的预热温度使索特平均直径降低,提高了雾化质量。更多还原

【Abstract】 Marine diesel engine using low-quality oil is aimed at rational using oil resources and reducing operating costs. But the physical and chemical properties of heavy oil are much worse than diesel. So, the pretreatment of heavy oil before using is very important. Pre-warming is one of the effective measures. For the internal combustion engine, the spray is very important. The quality of atomization determines the quality of the formation of flammable mixture, which affects the combustion, and ultimately will affect the dynamics, economy and emission of internal combustion engines. Therefore organize the fuel spray will play a decisive role to the indicators of the IC-engine. And the quality of the spray will be more important when using heavy oil.After comprehensive analyzing the mechanism of current research in the IC-engine fuel injection atomization and research results, establish a suitable mathematical physics model. Simulate the spray of 20# heavy diesel by Multi-dimensional numerical model.Cavitating flow plays a vital role in atomization. Taking account flipped will not happen in real live. By changing the geometry of nozzle control the flow in the nozzle, discuss the spray in single-phase flow and cavitating flow respectively. Calculate the change of the physicochemical parameters of 20# heavy oil with the change of temperature. Study the spray of 20# heavy oil in different injection pressure, nozzle diameter and pre-warming temperature.Research shows that cavitating flow play a positive role to the spray. Compared to single-phase flow, it will get longer penetration, smaller SMD and so on. It will get longer penetration and smaller SMD when raising injection pressure. Pre-warming plays a positive role in spray. It improves the atomization quality of the 20# heavy diesel.更多还原