郭建军, 刘一泽, 邬斌扬, 苏万华.高充量密度重型柴油机燃烧室形状优化数值模拟研究[J].内燃机工程,2021,42(2):72-81.
高充量密度重型柴油机燃烧室形状优化数值模拟研究
Numerical Simulation of Piston Bowl Optimization for Heavy-Duty Diesel Engines with High Charge Density
DOI：10.13949/j.cnki.nrjgc.2021.02.010
关键词:重型柴油机  燃烧室  热效率  充量密度
Key Words:heavy duty diesel engine  piston bowl  thermal efficiency  charge density
基金项目:国家重点研发计划项目(2017YFE0102800)；天津市面上基金项目(19JCYBJC21200)；移动源污染排放控制技术国家工程实验室开放基金项目(NELMS2018A05)
作者单位
郭建军, 刘一泽, 邬斌扬, 苏万华 天津大学 内燃机燃烧学国家重点实验室, 天津 300072 
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摘要:为解决采用较高充量密度后出现的燃烧室与喷雾匹配不合理的问题，基于一台采用阶梯（stepped lip）型燃烧室的重型柴油机，利用计算流体动力学软件CONVERGR建立了仿真模型并进行了标定验证，在中低转速全负荷工况、高充量密度条件下，通过三维数值模拟研究了燃烧室的唇口直径、唇口深度、底部凹弧半径的变化对缸内燃烧过程和传热损失的影响规律，并以进一步提高高压循环指示热效率为主要目标对燃烧室形状进行了优化。结果表明，在较高充量密度条件下宜采用相对较扁平、唇口深度较小、凹弧半径适中的燃烧室。对燃烧室进行优化后，燃烧后期放热速率加快，传热损失减少，高压循环指示热效率由49.00%提高至49.47%，NOx 排放基本不变而碳烟排放减少了50%。
Abstract:To address the poor matching between piston bowl and spray due to in-cylinder charge density being increased, a simulation model of a heavy-duty diesel engine with stepped-lip piston bowl was established with CONVERGR, a computational fluid dynamics software, and was calibrated with the experimental data. The effects of the lip diameter, lip depth, and bottom arc radius of piston bowl on the combustion process and heat transfer loss at low and medium speeds with full load and high charge density were studied, and the shape of piston bowl was optimized to further improve the indicated thermal efficiency. Results show that a relatively flat piston bowl with small lip depth and moderate concave arc radius should be applied when the charge density in the cylinder was higher. The optimization brought higher heat release rate in the later stage of combustion and lower heat transfer loss, making the indicated thermal efficiency increase from 49.00% to 49.47%. At the same time, the NOx emissions were basically unchanged while the soot emissions were reduced by 50%.
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