Experimental and theoretical investigation of transient fluid dynamic phenomena in the vicinity of automotive fuel injectors

汽车喷油器附近瞬态流体动力学现象的实验和理论研究

• 批准号: 1793447
• 金额: --
• 依托单位: University of Brighton
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1793447
• 关键词: Experimental; theoretical; investigation; transient; fluid

Understanding the mechanisms that lead to the atomisation and evaporation of liquid fuels is a key step towards the design of efficient and clean combustion systems. The vast majority of fuel spray research is focused on steady-state atomisation processes and based on the assumption that droplets are perfectly spherical, even though such sprays can contain a large proportion of ligaments and deformed droplets. The lack of information about transient atomisation and mixing processes (i.e. during start and end of injection) at the microscopic scale inhibits the development and validation of accurate engine simulation tools. For example, after the end of fuel injection, residual fuel present inside the injector's nozzle is discharged through inertia and capillarity. These uncontrolled fuel discharge events can present several problems. The excess fuel can undergo incomplete combustion due to its large, slow moving and often surface-bound nature. Not only does this have a negative effect on emissions and performance, but the by-products of incomplete combustion are thought to be implicated in the growth of carbonaceous deposits on the tips of fuel injectors. Accumulation of these deposits is known to lead to premature fuel injector failure that can lead to reductions in power output and engine lifetime. With modern multiple-injection strategies giving rise to an increased number of transient injection phases, post-injection discharges are increasingly problematic for modern engines

了解导致液体燃料雾化和蒸发的机制是设计高效清洁燃烧系统的关键一步。绝大多数燃料喷雾研究都集中在稳态雾化过程上，并且基于液滴是完美球形的假设，即使这种喷雾可能包含很大比例的韧带和变形液滴。在微观尺度上缺乏关于瞬态雾化和混合过程（即在喷射开始和结束期间）的信息，阻碍了精确发动机模拟工具的开发和验证。例如，在燃油喷射结束后，存在于喷油器喷嘴内的残余燃油通过惯性和毛细作用排出。这些不受控制的燃料排放事件会带来几个问题。由于其体积大、移动缓慢且经常是表面结合的性质，多余的燃料可能经历不完全燃烧。这不仅对排放和性能有负面影响，而且不完全燃烧的副产品被认为与燃料喷射器尖端的碳质沉积物的生长有关。众所周知，这些沉积物的积累会导致喷油器过早失效，从而导致功率输出减少和发动机寿命缩短。随着现代多重喷射策略导致瞬态喷射阶段数量的增加，现代发动机的喷射后排放问题日益严重