Improvements to direct-injection spark ignition engines by advanced technologies

最新的直喷式火花点火发动机在喷射正时和使用多种喷射策略方面具有很大的灵活性。其他技术也可以对发动机有利，例如改进点火过程，实施分层EGR(废气再循环)，或者使用生物燃料，在考虑到燃料的生命周期时，减少温室气体排放。在这项研究计划中，建议研究多种喷射策略要求作为不同生物燃料的函数的影响，并表征由此产生的混合气点火要求。此外，由申请者提出的新的分层废气再循环系统将被开发和测试，作为一种减少燃油消耗和污染物排放的方法。因此，将使用火花点火发动机进行实验，包括多次喷射生物燃料、火花放电特性的参数研究和分层EGR的实施。为了了解这些现象，并帮助解释发动机中观察到的行为，将使用大涡模拟(LES)方法进行燃油喷雾实验和模拟。这些实验将允许分离不同的参数，并通过先进的光学诊断来查看其对混合物形成过程的影响。燃油喷雾的LES将包括改进液滴碰撞模型。此外，还将建立包括火焰和离解动力学的火花放电LES模型，以量化分层EGR和流动混合气对火花点火特性的影响。这两个模型都可以满足发展先进的建模能力的长期目标，在发动机设计中使用，同时也为发动机中观察到的结果提供合理的解释。拟议中的研究计划的影响可能是深远的。例如，通过将燃料特性和发动机性能联系起来，该研究计划可以帮助确定“必备”生物燃料特性或潜在的生物燃料。后者可能被证明对下一代可再生燃料有帮助，这将使加拿大的生物燃料行业受益。此外，生物燃料具有减少温室气体排放的潜力，加拿大拥有很高的生物质可获得性。通过先进的喷射策略改进直喷发动机，本文建议的先进的EGR和生物燃料也将有助于达到加拿大的清洁燃料标准，到2030年每年减少30公吨温室气体排放。

The latest direct-injection spark ignition engines possess a great flexibility with respect to injection timing and the use of multiple injection strategies. Other technologies can also be beneficial to the engine such as improvement to the ignition process, the implementation of stratified EGR (exhaust gas recirculation), or the usage of biofuels that offer reduced greenhouse gas emissions when the fuel life-cycle is considered. In this research program, it is proposed to study the impact of multiple injection strategy requirements as a function of different biofuels as well as to characterize the resulting mixture ignition requirements. Moreover, a new stratified EGR system proposed by the applicant will be developed and tested as a means to reduce fuel consumption and pollutant emissions. Thus, experiments will be conducted using spark ignition engines and will involve multiple injection of biofuels, parametric study of the spark discharge characteristics and the implementation of a stratified EGR. To gain an understanding of the phenomena at play and to help explaining the observed behaviour in the engine, fuel spray experiments and simulations using a Large Eddy Simulations (LES) approach will be pursued. The experiments will allow isolating different parameters and to see its impact on the mixture formation process through advance optical diagnostics. LES of the fuel spray will include improvement to droplet collision model. Moreover, a spark discharge LES model will be developed including flame and dissociation kinetics to quantify the impact of spark ignition characteristics under stratified EGR and flowing mixture. Both models allow meeting long-term goal of developing advanced modelling capability to that are used in engine design while also offering a rational explanation.on for the observed results in engine. The impact of the proposed research program could be far-reaching. For example, by linking fuel properties and engine performance, the research program could help identify "must-have" biofuel properties or potential biofuels. The latter could prove helpful with the next generation of renewable fuels that will benefit the Canadian biofuel industry. Moreover, biofuels have the potential to reduce GHG and Canada has a high biomass availability. By improving DISI engines through advanced injection strategy, advanced EGR and biofuels, as proposed herein, will also help reaching Canada's Clean Fuel standard to reduce GHG emissions by 30 Mt/year by 2030.