Computational fluid dynamics (CFD) simulations of a single-cylinder gasoline compression ignition engine are performed to investigate the impact of gasoline-ethanol blending on autoignition, nitrogen oxide (NOx), and soot emissions under low-load conditions. A four-component toluene primary reference fuel (TPRF) + ethanol (ETPRF) surrogate (with 10% ethanol by volume; E10) is employed to represent the test gasoline (RD5-87). A 3D engine CFD model employing finite-rate chemistry with a skeletal kinetic mechanism, adaptive mesh refinement (AMR), and hybrid method of moments (HMOM) is adopted to capture in-cylinder combustion and soot/NOx emissions. The engine CFD model is validated against experimental data for three gasoline-ethanol blends: E10, E30 and E100, with varying ethanol content by volume. Model validation is carried out for multiple start-of-injection (SOI) timings (-21, -27, -36, and -45 crank angle degrees after top-dead-center (aTDC)) with respect to in-cylinder pressure, heat release rate, combustion phasing, NOx and soot emissions. For late injection timings (-21 and -27oaTDC), E30 yields higher soot than E10; while the trend reverses for early injection cases (-36 and -45oaTDC). E100 yields the lowest amount of soot among all fuels irrespective of SOI timing. Further, E10 shows a non-monotonic trend in soot emissions with SOI timing: SOI-36>SOI-45>SOI-21>SOI-27, while soot emissions from E30 exhibit monotonic decrease with advancing SOI timing. NOx emissions from various fuels follow a trend of E10>E30>E100. NOx emissions increase as SOI timing is advanced for all fuels, with an anomaly for E10 and E100 where NOx decreases when SOI is advanced beyond -36oaTDC. Detailed analysis of the numerical results is performed to investigate the emission trends and elucidate the impact of chemical composition and physical properties on autoignition and emissions characteristics.

翻译：采用计算流体动力学（CFD）对单缸汽油压燃发动机进行模拟，研究低负荷条件下汽油-乙醇混合对自燃、氮氧化物（NOx）及碳烟排放的影响。以四组分甲苯基础参比燃料（TPRF）与乙醇（ETPRF）的替代燃料（含10%体积乙醇；E10）代表试验汽油（RD5-87）。采用结合有限速率化学的骨架反应机理、自适应网格加密（AMR）及混合矩方法（HMOM）的三维发动机CFD模型，捕捉缸内燃烧及碳烟/NOx排放特性。针对三种不同乙醇体积含量的汽油-乙醇混合燃料（E10、E30及E100），通过与实验数据对比验证发动机CFD模型。模型验证涵盖多个喷油正时（SOI：-21、-27、-36及-45曲轴转角，以上止点后aTDC表示），对标缸压、放热率、燃烧相位、NOx及碳烟排放。对于晚期喷油正时（-21及-27oaTDC），E30的碳烟排放高于E10；而早期喷油（-36及-45oaTDC）趋势相反。无论SOI正时如何，E100的碳烟排放量在所有燃料中最低。此外，E10的碳烟排放随SOI正时呈现非单调变化：SOI-36>SOI-45>SOI-21>SOI-27，而E30的碳烟排放随SOI提前单调递减。不同燃料的NOx排放趋势为E10>E30>E100。所有燃料的NOx排放均随SOI提前而增加，但E10及E100在SOI提前至-36oaTDC后出现NOx下降的反常现象。对计算结果进行详细分析，探究排放趋势，阐明化学组分与物理性质对自燃及排放特性的影响。