乙烯超声速燃烧部分预混火焰面模型数值研究

Numerical Simulation of Ethylene Supersonic Combustion Using Partially Premixed Flamelet Model

关键词:  超声速燃烧  数值模拟  部分预混  火焰面模型  乙烯

Key words:  Supersonic combustion  Numerical simulation  Partially premixed  Flamelet model  Ethylene

摘要:

湍流涡结构的作用导致以扩散形式喷射燃料的超声速燃烧过程通常以部分预混的方式进行，为了使火焰面模型对这一燃烧过程描述的更准确，在模型中对扩散燃烧和预混燃烧状态均需要予以合理考虑。基于低Ma条件多区域火焰面模型(MRF)思想，发展得到了适用于超声速条件的部分预混火焰面模型。以碳氢燃料超声速双燃烧室结构作为验证算例，采用k-ω SST湍流模型、部分预混火焰面模型和乙烯(C2H4)的28组分72步化学反应机理对超声速湍流燃烧流场进行了数值研究。计算结果与实验数据吻合良好，验证了模型的准确性。加权系数计算结果表明，在中心剪切层和下壁面附近区域流场主要由预混燃烧控制，而其他大部分区域则由扩散燃烧控制。

Abstract:

Supersonic combustion as a form of non-premixed injection is actually partially premixed because of turbulent vortex. In order to obtain a more accurate prediction of the combustion process by flamelet model，both the non-premixed and the premixed regimes should be properly simulated. A multi-regime flamelet(MRF)model proposed for low Mach number flows has been modified and developed under supersonic conditions. Employing the k-ω SST turbulence model，the modified MRF model and the ethylene(C2H4) chemical kinetic mechanism including 28 species and 72 steps，the flow field of a hydrocarbon-fueled dual combustor was numerically investigated as test case. Good agreement between calculation and experiments validates the accuracy of the modified MRF model. The distribution of the weighting coefficient illustrates that the premixed mechanism dominates in the central shear layer and the boundary layer near the lower wall，while the rest of the flow field is mainly non-premixed.