汽油机进气道及燃烧室结构优化与性能研究

Research on Structural Optimization and Performance of Intake Port and Combustion Chamber of Gasoline Engine

通过优化进气道和燃烧室结构来提升某缩缸后排量0.375 L的单缸汽油机的性能,达到小型强化的目的。利用CONVERGE软件对发动机进行不同气门升程下气道稳态数值模拟和3000 r/min满负荷工况下的瞬态燃烧过程模拟。分别提出4种进气道优化方案和3种燃烧室优化方案。综合考虑流量系数和滚流比,选取优化进气道方案A。采用方案A进气道,平均流量系数提升22.26%,平均滚流比提升14.41%。在选用进气道方案A的前提下,综合分析不同燃烧室方案下流场分布、混合气分布、温度分布、缸内压力和燃烧相关参数,最终确定燃烧室优化方案2的缸内流场分布、湍动能和混合气分布情况能增加火焰传播速度,缩短急燃期,指示功率较缩缸后原方案提升14.1%,动力性能达到缩缸前0.400 L排量发动机的水平。

The performance of a single-cylinder gasoline engine(0.375 L)was improved by optimizing the structures of intake port and combustion chamber to achieve the purpose of downsizing.The CONVERGE software was used to simulate the steady-state air flow in the intake port at different valve lifts and the combustion process at 3000 r/min with full load.Four optimization schemes of intake port and three optimization schemes of combustion chamber were proposed respectively.Considering flow coefficient and tumble ratio comprehensively,the first scheme of intake port was selected.With the selected intake port,the average flow coefficient was increased by 22.26%,and the average tumble ratio was increased by 14.41%.The flow distribution,turbulence kinetic energy and mixture distribution of the second combustion chamber scheme could accelerate flame propagation speed and shorten fast combustion period after comprehensively analyzing the flow distribution,mixture distribution,temperature distribution,cylinder pressure and combustion parameters of different combustion chamber schemes based on the first intake port scheme.The indicated power of the second scheme of combustion chamber was increased by 14.1%compared to the base combustion chamber,and the power performance reached the level of the base engine(0.400 L).