高温下正十二烷喷雾及燃烧数值模拟研究

Numerical simulation of n-dodecane spray and combustion at high temperature

耦合RANS湍流模型、KH-RT破碎模型及SAGE燃烧模型,运用CFD数值模拟平台,对正十二烷在高温定容状态下的喷雾及燃烧现象进行研究。首先进行喷雾模型的标定与验证,确定了适合模拟的最小网格尺寸,然后分析若干边界条件对于正十二烷喷雾着火的影响规律。结果表明,环境压力对正十二烷喷雾尖端平均推进速率的影响程度不大;随着环境温度的升高,正十二烷喷雾的气相贯穿距不断增大,液相贯穿距呈现下降趋势,但变化并不明显;随着环境温度、环境氧浓度的升高,正十二烷喷雾滞燃期在不断地缩短,着火位置越来越靠近喷嘴。

Coupled with RANS turbulence model,KH-RT break-up model and SAGE combustion model,CFD numerical simulation platform was used to study the spray and combustion of n-dodecane at high temperatures and constant volume.Firstly,the spray model was calibrated and verified to determine the minimum mesh size suitable for simulation.Then the influences of several boundary conditions on n-dodecane spray and ignition were analyzed.The results show that ambient pressure has slight effect on the average advancing velocity of n-dodecane spray tip.With the rise in ambient temperature,the gas penetration length of n-dodecane spray increases,while its liquid penetration length decreases even though the change is not obvious.As the ambient temperature and oxygen concentration increase,ignition delay period of n-dodecane spray is continuously shortened,and the ignition location is closer and closer to the nozzle.