Theoretical prediction model and experimental investigation of detonation limits in combustible gaseous mixtures
Theoretical prediction model and experimental investigation of detonation limits in combustible gaseous mixtures
复制标题
可燃气体混合物爆炸极限的理论预测模型和实验研究
DOI：
10.1016/j.fuel.2019.116132
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发表时间：
2019
期刊：
影响因子：
7.4
通讯作者：
Liu Hong
中科院分区：
文献类型：
--
作者：
Zhang Bo;Liu Hong
由于安全保护和预防措施的原因，气体爆轰的传播极限是工业化学过程中的一个重要问题。传播极限对新概念爆震发动机的研制也具有重要意义。由于近极限爆轰现象的复杂性以及混合物性质和边界条件之间的多重竞争机制，发展一种通用的理论预测模型来满意地估计极限附近的爆速差(实际爆速与理论CJ爆速之差)仍然是非常具有挑战性的。本文主要研究了爆轰结构与预测模型之间的本质联系。通过分析ZND模型爆轰结构中的化学长度尺度，发现ΔI(诱导长度)和ΔR(放热长度)是重要的长度尺度，它们与反应区厚度(X)之间存在如下关系：x=C·(Δi+α·ΔR)。结合Fay的边界层理论，提出了一种修正的理论预报模型。并与前人的Fay模型和实验结果进行了比较。为了验证MF模型的可靠性，对三种燃烧混合物(CH4-2O2、2H2-O2和C2H4-6N2O)和三种不同内径的管子(d= 36、14和4 mm)进行了研究。结果表明，MF模型能较好地预测近极限条件下的爆轰亏差。在大尺度管(d= 36 mm)中，与实验数据的最大误差为9.3%。在微尺度管(d= 4 mm)中，最大差值为10.7%。如果考虑实验测量误差，则MF模型的预测具有合理的精度。结果表明，爆轰结构对爆轰极限预测有重要影响。
Propagation limits in gaseous detonation are an important problem in industrial chemical processes due to safety protections and precautions. Propagation limits are also of great significance for developing new-concept detonation engines. Due to the complex phenomena of near-limit detonation and the multiple competing mechanisms between the properties of mixtures and boundary conditions, development of a universal theoretical prediction model that can satisfactorily estimate the detonation velocity deficit (the difference between the actual detonation velocity and the theoretical CJ detonation velocity) near the limits is still extremely challenging. This work focuses on the essential relation between the detonation structure and prediction models. By analyzing the chemical length scales in the detonation structure of the ZND model, it is found that ΔI(induction length) and ΔR(exothermic length) are important length scales and that they are related to the reaction zone thickness (x) by:x=C·(ΔI+α·ΔR). In combination with Fay’s boundary layer theory, a modified theoretical prediction model (MF) is proposed. The MF model is also compared with previous Fay models and experimental results. To verify the reliability of the MF model, three combustion mixtures (CH4-2O2, 2H2-O2and C2H4-6N2O) and tubes with three different inner diameters (d= 36, 14 and 4 mm) are investigated. The results show that the MF model satisfactorily predicts the detonation deficit at the near-limit conditions. In the macroscale tube (d= 36 mm), the maximum difference with the experiment data is 9.3%. In the microscale tube (d= 4 mm), the maximum difference is 10.7%. If experimental measurement error is considered, the prediction of the MF model has reasonable accuracy. The results confirm that the detonation structure has an important impact on detonation limit predictions.