高原环境下重型柴油机的性能优化研究

Performance Optimization of Heavy-duty Diesel Engine in Plateau Environment

为改善重型柴油机在高原环境下的动力下降和燃烧恶化等问题,针对某型重型柴油机进行了不同海拔高度(简称海拔)及不同柴油-空气-燃烧室(简称油-气-室)匹配方案的性能优化研究。通过模拟海拔4 500 m的高原进气状态,开展了重型柴油机不同压缩比、涡流比和喷油器喷孔直径的试验研究。结果表明,随着海拔的升高,柴油机实际运行工况呈现由低速、低负荷向高速、高负荷工况迁移的特性。研究了海拔4 500 m高原环境下柴油机5种油-气-室匹配方案下的性能,5种方案分别为:方案A(涡流比2.2,喷油器10×0.32 mm,压缩比13.3)、方案B(涡流比2.2,喷油器10×0.32 mm,压缩比14.1)、方案C(涡流比1.5,喷油器10×0.32 mm,压缩比13.3)、方案D(涡流比1.5,喷油器10×0.32 mm,压缩比14.1)和方案E(涡流比1.5,喷油器10×0.30 mm,压缩比14.1)。油-气-室匹配仿真与试验研究结果显示:适当提高压缩比、降低涡流比以及选取适当的喷孔直径,可提高柴油机在高原环境下油-气-室的匹配状况;最佳方案D的油-气-室匹配效果最优,柴油机动力性、经济性和排放性均有较明显的改善。

The performances of different fuel-air-chamber matching schemes at different altitudes are optimized for a heavy-duty diesel engine. The results show that,with the increase in altitude,the actual operating conditions of diesel engine are shifted from low speed and low load to high speed and high load.The five schemes are presented,such as Scheme A（ swirl ratio of 2. 2,10 × 0. 32 mm injector,and compression ratio of 13. 3）,Scheme B（ swirl ratio of 2. 2,10 × 0. 32 mm injector,and compression ratio of 14. 1）,Scheme C（ swirl ratio of 1. 5,injector 10 × 0. 32 mm,and compression ratio of 13. 3）,Scheme D（ swirl ratio of 1. 5,10 × 0. 32 mm injector,and compression ratio of 14. 1）,and Scheme E（ swirl ratio of 1. 5,10 × 0. 30 mm injector,and compression ratio of 14. 1）. Simulated and experimental results show that the fuel-air-chamber matching condition of diesel engine in plateau environment can be improved by appropriately increasing the compression ratio,reducing the swirl ratio and selecting the appropriate nozzle diameter. The difference between the internal and external equivalent ratios of the best scheme is smaller. The fuel-air-chamber optimization of the best scheme is optimal,and the power,economy and emission performance of diesel engine are improved.