煤油总包反应机理对超声速燃烧的影响

Effects of Kerosene Global Reaction Mechanisms on Supersonic Combustion

关键词:  超声速燃烧  数值模拟  煤油  化学反应机理  热壅塞 

Key words:  Supersonic combustion  Numerical simulation  Kerosene  Chemical kinetic mechanism  Thermal choking

摘要:

为考察不同总包反应机理对超声速燃烧数值模拟的影响,以煤油燃料超燃冲压发动机支板加凹腔燃烧室为研究对象,分别采用单步和两步总包反应机理对其燃烧过程进行了三维数值模拟研究。对比分析表明,采用的单步反应机理计算结果与实验值呈现明显差异；而两步反应机理的壁面静压计算结果与实验数据吻合良好,验证了计算过程的有效性。该单步反应机理在前支板处局部反应释热量过大过快,致使超燃室内出现热壅塞现象；而两步反应机理的反应和释热规律更为合理,更逼近真实燃烧过程。 

Abstract:

To investigate the effects of different global chemistry kinetics on supersonic combustion simulation, a three-dimensional numerical simulation of a kerosene-fueled strut-cavity-based supersonic combustor was performed using two different global reaction mechanisms, namely the one-step and the two-step mechanisms. Comparisons between the predicted static pressure distribution along the combustor walls and experimental data show that there is obvious discrepancy found in the one-step case. On the other hand, good agreement between computation and experiments was obtained by the two-step mechanism, validating its effectiveness and availability. In the one-step calculation, over-predicted heat release near the front struts leads to thermal choking, thus the combustor can no longer work properly. The rules of chemical reaction and heat release generated by the two-step mechanism are more reasonable and closer to the authentic combustion process. 