Investigating the effects of ammonia injection position and timing on the formation and combustion characteristics of ammonia/hydrogen rotary engine

作者：Pengzhen Li, Jianfeng Pan, Baowei Fan, Qingbo Lu, Yi Zhang, Muhammad Nauman, Wenming Yang · 发表于：Physics of Fluids · 年份：2025 · DOI：10.1063/5.0307726 · 研究领域：Advanced Combustion Engine Technologies、Combustion and flame dynamics、Biodiesel Production and Applications

Ammonia/hydrogen blended fuel offers a promising alternative for reducing greenhouse gas emissions in engines. This study combines experimental and numerical simulations to validate a model and examine the impact of ammonia injection position and timing on mixture formation and combustion in a rotary engine. Results reveal that, under direct injection conditions, an ammonia jet angle greater than 90° leads to a high fuel concentration at the cylinder's front, while angles less than 90° cause concentration at both the front and rear. Injection at 190° CA (Crank Angle) before top dead center (TDC) results in nearly complete flame filling with a small high fuel concentration zone at the rear. Delaying injection timing initially shortens, then lengthens the ignition delay, and increases peak pressure, reaching a peak value of 1.79 MPa at 190° CA before TDC—43% higher than in premixed conditions. The highest heat release rate occurs closest to TDC, indicating optimal energy efficiency. Rear injection maintains a high heat release rate after TDC, leading to higher exhaust temperatures and NOx emissions. Specifically, NO and NO2 emissions vary drastically with injection position-timing combinations: The AIP (Ammonia Injection Position)-A mode produces the highest NOx, with case A-310's NO emissions 28-fold and 37-fold higher than cases B-190 and C-130, respectively, and NO2 emissions 87-fold and 444-fold higher. This study underscores the potential of ammonia/hydrogen blends for enh...