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

受控自动点火（CAI）、均质充量压缩点火（HCCI）和汽油受控自动点火（GCAI）燃烧代表了一种既能减少汽油发动机的NOx排放又能减少燃料消耗以及柴油发动机的NOx和颗粒排放的技术。然而，在CAI/HCCI/GCAI发动机中控制自动点火和压力上升速率的困难仍然是一个重要的问题。在建议的项目中，将提高对预喷射（PI）对主燃烧的化学效应的理解。为了这个目的，由PI形成的反应物种，如H2 O2，HO 2，和OH的建议进行实验探测和数值模拟。还将提议在第二个供资期内调查这些物质对主燃烧相位和压力上升率的影响，第二年H2 O2的测量将尝试通过光致碎裂激光诱导荧光（PFLIF），特别是在早期的压缩冲程的光学GCAI发动机。通过3D-CFD（三维计算流体动力学）缸内反应流模拟以及OH的其他潜在前体来量化HO 2和OH的潜在PFLIF信号贡献。PFLIF和OH-LIF的信号贡献建议通过实验手段分离。它将试图在圆柱体中产生近似均匀的物质分布。这将通过空间分辨PFLIF/ LIF（激光诱导荧光）测量进行验证。如果建立了均匀的H2 O2场，并且HO 2的PFLIF信号贡献可以忽略不计，则建议在第二个资助期内通过实验量化整个气缸中的H2 O2总量。建议项目的主要目标是在第一个资助期内回答以下问题：在早期压缩冲程中，PFLIF能否选择性地测量H2 O2？PFLIF信号是否足够强以进行空间分辨和/或单次测量？在相关的发动机工作条件下是否可以进行此操作？如果H2 O2（或HO 2/OH）可以选择性地测量在相关的操作条件下与近似均匀的物种分布在早期的压缩冲程，它将被提议回答以下问题在第二个资助期（除其他外）：H2 O2测量的PFLIF是一个很好的指标的化学影响PI的主要自燃？H2 O2是PI产生的“触发”主燃烧的决定性物质吗？与再压缩过程中的高温燃烧相比，中温反应对PI的化学效应有多重要？在再压缩过程中混合物均匀化的效果是什么？燃烧不稳定性，如循环到循环的变化，漂移燃烧相位，和前循环的影响，可以解释所考虑的物种？

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?