Investigation of the Chemical Effect of Pilot Injection on Main Combustion in a Gasoline Controlled Auto-Ignition Engine by In-Cylinder Measurements and Numerical Simulation of H2O2, HO2, and OH

通过 H2O2、HO2 和 OH 的缸内测量和数值模拟研究引燃喷射对汽油控制自动点火发动机主燃烧的化学影响

• 批准号: 389807373
• 负责人: Professor Dr.-Ing. Hans-Jürgen Koß
• 金额: --
• 依托单位: Lehrstuhl für Thermodynamik mobiler Energiewandlungssysteme (TME)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389807373?language=en
• 关键词: Investigation; Chemical; Effect; Pilot; Injection

Controlled auto-ignition (CAI), homogeneous charge compression-ignition (HCCI), and gasoline controlled auto-ignition (GCAI) combustion represents a technology that can reduce both NOx emissions and fuel consumption of gasoline engines as well as NOx and particulate emissions of diesel engines. However, the difficulty in controlling auto-ignition and pressure-rise rate in CAI/HCCI/GCAI engines continues to be an important issue. In the proposed project, the understanding of the chemical effect of pilot injection (PI) on main combustion will be improved. For this purpose, reactive species formed by PI such as H2O2, HO2, and OH are proposed to be experimentally probed and numerically simulated. It will also be proposed to investigate the effect of these species on main-combustion phasing and pressure-rise rate in the second funding period, i.e., the second year. The measurement of H2O2 will be attempted by photo-fragmentation laser-induced fluorescence (PFLIF), particularly in the early compression stroke of an optical GCAI engine. Potential PFLIF signal contributions by HO2 and OH will be quantified by 3D-CFD (three dimensional computational fluid dynamics) in-cylinder reactive flow simulations, as well as other potential precursors to OH. Signal contributions by PFLIF and OH-LIF are proposed to be separated by experimental means. It will be attempted to produce approximately homogeneous species distributions in the cylinder. This will be verified by spatially resolved PFLIF/ LIF (laser-induced fluorescence) measurements. If homogenous H2O2 fields are established and PFLIF signal contributions by HO2 are negligible, it will be proposed to quantify the total amount of H2O2 experimentally in the entire cylinder within the second funding period. It is a major objective of the proposed project to answer the following questions within the first funding period: Can H2O2 be measured selectively by PFLIF in the early compression stroke? Are PFLIF signals strong enough for spatially resolved and/or single-shot measurements? Can this be conducted under relevant engine operating conditions?If H2O2 (or HO2/OH) can be measured selectively under relevant operating conditions with approximately homogeneous species distributions in the early compression stroke, it will be proposed to answer the following questions in the second funding period (among others):Is H2O2 measured by PFLIF a good indicator of the chemical effect of PI on main auto-ignition? Is H2O2 the decisive species produced by PI that 'triggers' main combustion? How important are intermediate-temperature reactions compared to high-temperature combustion during re-compression for the chemical effect of PI? What is the effect of mixture homogenization during re-compression? Can combustion instabilities, such as cycle-to-cycle variations, drifting combustion phasing, and prior-cycle effects, be explained by the considered species?

控制自动点火（CAI）、均质装药压缩点火（HCCI）和汽油控制自动点火（GCAI）燃烧代表了一种既可以减少汽油发动机的氮氧化物排放和燃料消耗，也可以减少柴油发动机的氮氧化物和颗粒排放的技术。然而，CAI/HCCI/GCAI发动机在控制自动点火和升压速率方面的困难仍然是一个重要的问题。在该项目中，将提高对先导喷射（PI）对主燃烧的化学效应的理解。为此，我们提出对由PI形成的H2O2、HO2和OH等活性物质进行实验探索和数值模拟。还将建议在第二个资助期，即第二年，调查这些物种对主燃烧阶段和压力上升率的影响。H2O2的测量将尝试通过光破碎激光诱导荧光（PFLIF），特别是在光学GCAI引擎的早期压缩行程中。HO2和OH对pfif信号的潜在贡献将通过3D-CFD（三维计算流体动力学）缸内反应流模拟以及其他潜在的OH前体来量化。提出了用实验方法分离pflf和OH-LIF的信号贡献。它将试图在圆柱体中产生近似均匀的物种分布。这将通过空间分辨pflf / LIF（激光诱导荧光）测量来验证。如果建立了均匀的H2O2场，并且HO2对pflf信号的贡献可以忽略不计，将提出在第二个资助期内通过实验量化整个圆柱体中H2O2的总量。该项目的主要目标是在第一个资助期内回答以下问题：在压缩冲程早期，PFLIF是否可以选择性地测量H2O2 ？PFLIF信号是否足够强，可以进行空间分辨和/或单次测量？是否可以在相关的发动机运行条件下进行？如果H2O2（或HO2/OH）可以在相关的操作条件下有选择地测量，并且在早期压缩行程中物种分布近似均匀，那么将在第二个资助期（其中包括）提出回答以下问题：PFLIF测量的H2O2是否是PI对主自燃的化学效应的良好指标？H2O2是由PI产生的“触发”主要燃烧的决定性物质吗？再压缩过程中的中温反应与高温燃烧相比，对PI的化学效应有多重要？再压缩过程中混合物均质化的影响是什么？燃烧不稳定性，如循环之间的变化、漂移燃烧相位和循环前效应，可以用考虑的物种来解释吗？