首页> 外文会议>Proceedings of the 2009 spring technical conference of the ASME Internal Combustion Engine Division >INVESTIGATION OF IN-CYLINDER MIXING USING LARGE EDDY SIMULATION MODELS FOR LTC DIESEL APPLICATIONS
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INVESTIGATION OF IN-CYLINDER MIXING USING LARGE EDDY SIMULATION MODELS FOR LTC DIESEL APPLICATIONS

机译:LTC柴油机应用大涡模拟模型的缸内混合研究

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In-cylinder mixture preparation and early combustion heat release are studied using Large Eddy Simulation (LES) for direct injection (DI) diesel with high exhaust gas recirculation (EGR) and early injection timing. Both LES and traditional Reynolds Average Navier-Stokes (RANS) calculations are carried out using KIVA-3V release 2 and compared with experimental results of medium load LTC-diesel (Low Temperature Combustion) cases. Simulations presented in this paper are carried out using KH-RT (Kelvin Helmholtz -Rayleigh Taylor) breakup model for spray atomization and CHEMKIN n-heptane mechanism for combustion and both dynamic structure LES and RNG (re-normalized group) kε RANS for turbulence model. Although engine simulation using LES model poses significant challenges on practical engine grids, significant agreement with LTC-diesel experiments is observed by using an additional spray source term for modeling the effect of liquid sprays on sub-grid kinetic energy transport calculation in engines. Results when compared to RANS, demonstrate that LES is able to predict local spots of early heat release resulting in more accurate prediction of start of combustion timing and early heat release phasing. Mixing due to bulk fluid motion such as swirl is also observed more distinctively in LES calculations.
机译:使用大涡模拟(LES)对具有高排气再循环(EGR)和早期喷射正时的直接喷射(DI)柴油进行了缸内混合气制备和早期燃烧放热的研究。 LES和传统雷诺平均Navier-Stokes(RANS)计算都是使用KIVA-3V版本2进行的,并与中等负荷LTC柴油(低温燃烧)情况的实验结果进行了比较。本文采用的模拟是使用KH-RT(Kelvin Helmholtz -Rayleigh Taylor)分解模型进行喷雾雾化和CHEMKIN n-庚烷燃烧机理以及动态结构LES和RNG(重新归一化组)kεRANS进行湍流模型进行的。尽管使用LES模型进行发动机仿真对实际的发动机网格提出了重大挑战,但通过使用附加的喷雾源术语对液体喷雾对发动机中子网格动能传输计算的影响进行建模,可以观察到与LTC柴油实验的显着一致性。与RANS相比,结果表明LES能够预测早期放热的局部结果,从而可以更准确地预测燃烧正时的开始和早期放热的阶段。在LES计算中,也可以更明显地观察到由于整体流体运动(例如涡流)引起的混合。

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