为解决当前汽车气动减阻设计中基于工程师经验的试凑法所带来的盲目性与低效性,以及车身曲面难于参数化的问题,作者将离散伴随法和试验设计(Design of Experiment,DOE)引入汽车减阻优化流程,以阶梯背式MIRA模型为研究对象,通过对外流场...为解决当前汽车气动减阻设计中基于工程师经验的试凑法所带来的盲目性与低效性,以及车身曲面难于参数化的问题,作者将离散伴随法和试验设计(Design of Experiment,DOE)引入汽车减阻优化流程,以阶梯背式MIRA模型为研究对象,通过对外流场进行数值计算,根据外流场特性和车辆表面灵敏度分析,确定优化变量;通过DOE创建样本空间,并采用网格变形技术对各优化变量进行参数化;通过CFD仿真获取各样本点的风阻系数;采用Kriging空间插值法来建立近似模型;使用自适应模拟退火算法对模型优化。优化后模型风阻系数较原模型共计降低16 counts,减阻5.4%,表明该方法在汽车气动减阻优化中有较好的减阻效果和可行性。展开更多
针对汽车车身局部修形传统气动减阻方法存在经验式和盲目性问题,以某款成熟简化实车发动机罩低阻曲面优化减阻为例,提出了基于硬点-骨架约束的车身低阻曲面优化设计法.采用DOE(design of experiment)试验设计方法对发动机舱罩进行硬点采...针对汽车车身局部修形传统气动减阻方法存在经验式和盲目性问题,以某款成熟简化实车发动机罩低阻曲面优化减阻为例,提出了基于硬点-骨架约束的车身低阻曲面优化设计法.采用DOE(design of experiment)试验设计方法对发动机舱罩进行硬点采样,通过硬点-骨架约束建立样本曲面.构建以硬点为设计因子,阻力系数为响应值的数学近似模型,并使用多岛遗传算法获得发动机舱罩理论最优解.计算表明:优化后的实车车模气动阻力减少3.32%,证明了硬点-骨架约束在车身减阻上的可行性和有效性.展开更多
The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the r...The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.展开更多
文摘为解决当前汽车气动减阻设计中基于工程师经验的试凑法所带来的盲目性与低效性,以及车身曲面难于参数化的问题,作者将离散伴随法和试验设计(Design of Experiment,DOE)引入汽车减阻优化流程,以阶梯背式MIRA模型为研究对象,通过对外流场进行数值计算,根据外流场特性和车辆表面灵敏度分析,确定优化变量;通过DOE创建样本空间,并采用网格变形技术对各优化变量进行参数化;通过CFD仿真获取各样本点的风阻系数;采用Kriging空间插值法来建立近似模型;使用自适应模拟退火算法对模型优化。优化后模型风阻系数较原模型共计降低16 counts,减阻5.4%,表明该方法在汽车气动减阻优化中有较好的减阻效果和可行性。
文摘针对汽车车身局部修形传统气动减阻方法存在经验式和盲目性问题,以某款成熟简化实车发动机罩低阻曲面优化减阻为例,提出了基于硬点-骨架约束的车身低阻曲面优化设计法.采用DOE(design of experiment)试验设计方法对发动机舱罩进行硬点采样,通过硬点-骨架约束建立样本曲面.构建以硬点为设计因子,阻力系数为响应值的数学近似模型,并使用多岛遗传算法获得发动机舱罩理论最优解.计算表明:优化后的实车车模气动阻力减少3.32%,证明了硬点-骨架约束在车身减阻上的可行性和有效性.
基金Project(50575202) supported by the National Natural Science Foundation of China
文摘The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.
