重型单缸柴油机燃烧过程强化研究

在1台排量为2.8L的单缸柴油机上,通过燃烧过程不断强化,将输出功率从73kW提高到150kW。研究分为两个阶段:第一阶段通过提高进气压力、降低进气阻力、优化配气相位、优化喷油系统参数,将输出功率从73kW提高到92kW;第二阶段采用了电控单体泵供油系统,并优化喷孔参数、进一步提高进气压力、降低进气温度、提高发动机转速,将输出功率提高到150kW。放热率分析结果表明:对于高强化燃烧过程,虽然预混和扩散燃烧阶段的放热速率大幅度增加,但其放热量占总放热量的比率下降,后燃阶段的放热比率显著增加。因此加强扩散燃烧阶段的放热速率仍然是高强化燃烧过程面临的主要问题。

Intensifying the Combustion Process on a Heavy-duty Single Cylinder Diesel Engine

Increasing power density is a promise technical measure for displacement downsize and fuel economy improvement.This paper describes a research into power increase from 73 kW to 150 kW by consecutive combustion process enhancement on a single-cylinder diesel engine with a displacement of 2.8 L.The research was conducted through two steps: The first step was to boost the power output to 92 kW by virtue of increasing intake pressure,reducing intake flow resistance,optimizing cam profile and modifying fuel injection system.The second step was to significantly increase the power to 150 kW by further increasing the intake pressure,raising the engine speed,using an electronic unit pump with a high injection pressure instead of the mechanical pump.The heat release analysis results show that the heat release rate is increased significantly for pre-mixed and diffusion combustion periods.However,the percentage of accumulated heat release during those periods to the total heat release is reduced considerably and hence the percentage of heat release during the late stage of the combustion is obviously increased.How to increase heat release rate during the diffusion combustion period is the main challenge for highly intensified combustion process development.