柴油机多脉冲喷射预混燃烧过程多维数值模拟

Multi-Dimensional Simulation of PCCI Combustion in a Diesel Engine with Multi-Pulse Injection

建立了三维CFD耦合化学反应动力学模型,对柴油机缸内多脉冲喷射形成的预混燃烧过程进行了模拟,结果表明:该模型能够较准确地预测缸压曲线、着火时刻、NOx和CO2排放,能够预测着火位置、燃烧中间产物和有害排放物的生成历程。多脉冲喷射预混燃烧产生的NOx、CO和未燃HC排放主要来源于靠近缸壁余隙内,要提高这种燃烧方式的效率和降低排放,关键是要减少燃油附壁。

The multi-dimensional CFD coupling with chemical kinetics model was developed to study the combustion process in premixed charge compression ignition （PCCI） engine with multi-pulse injection. Results show that the model can accurately predict in-cylinder pressure, ignition timings, NOx and CO2 emissions. Both the ignition zones and the formation of intermediate species and engine harmful emission species were clarified. The crevice zone close to cylinder liner is the main source of NOx, CO and uriC emissions in PCCI engine with multi-pulse injection, and this indicates that for the PCCI combustion to minimize wall-adhering fuel is the key to obtain high thermal efficiency and low emissions simultaneously.