基于油压策略的柴油机瞬变过程烟度优化研究

Study on Soot Optimization in Diesel Transient Process Based on Fuel Injection Strategies

以降低微粒排放为目标,在一台带旁通阀的二级涡轮增压重型柴油机上探索了不同油压策略对柴油机恒转速增转矩5s典型瞬变过程燃烧及微粒排放的影响。研究结果表明:二级涡轮增压器有助于改善柴油机负荷加载瞬变过程空气量供给,旁通阀关闭时采用全程增油压方式可有效降低瞬变过程烟度排放峰值;但随着旁通阀开度增大,提高油压却使烟度峰值不降反升;在旁通阀小开度下采用分段增油压策略,有助于改善发动机负荷加载初期缸内燃烧热力学状态,促进中大负荷阶段油气充分混合,并在10%旁通阀开度下实现最大烟度峰值降幅达51.5%;旁通阀开度增大也会导致燃油经济性恶化,而采用分段增油压策略能够有效抑制这一恶化趋势。

Aimed at reduction of smoke emission, the influence of fuel injection strategies on combustion and soot emission was conducted in two-stage turbocharged diesel engine with a by-pass valve under typical 5s transient process of constant speed and increase toque. The test results show that： two-stage turbocharger can be allowed to improve intake air supply, and provide significant soot reduction as the valve was closed under full-stage rail pressure augment strategy, but soot deterioration happened once valve opening got larger; with small valve opening, sectional-stage fuel injection augment strategy can be provided to improve in-cylinder thermodynamics conditions during early transient process, and then enhance air-fuel mixture much more better at larger load rate, and maximum soot decline reached up to 51.5%, which happened with valve opening by 10%; fuel consumption could be getting worse as well when valve opening became larger, but this deterioration situation can effectively be restrained by utilization of sectional-stage fuel injection augment strategy.