摘要
镁颗粒因其能量密度高、点火特性和燃烧效率好的优势,作为燃料或添加剂应用于爆震燃烧动力系统具有广阔的应用前景.本文建立了镁颗粒-空气混合物的一维稳态爆震波模型,数值模拟爆震波稳态传播过程及其内部流场分布.结果表明,镁颗粒-空气混合物爆震波仅能以特征值速度稳定自维持传播,特征值爆震速度的高低并不仅仅取决于反应放热多少,两相间的相互作用也会影响热能向气相动能的转化效率.当爆震波末端氧化镁处于熔化过程时,满足一定的来流速度和镁颗粒密度条件,爆震波仍能够稳定自维持传播.气相吸收反应放热膨胀加速至声速的过程主要发生在镁颗粒纯蒸发反应阶段,但在氧化镁熔化阶段由于熔化过程吸热量大,使气相吸热膨胀过程近乎停止.颗粒粒径变化主要影响爆震波尺寸,而对特征值爆震速度以及波后声速面参数影响甚微.在常温常压的初始条件下,爆震波稳定自维持传播过程中波内不涉及氧化镁的汽化离解过程.
Magnesium particles have broad application prospects as fuel or additive for detonation combustion power systems due to their high energy density,ignition characteristics and combustion efficiency.In this paper,a onedimensional steady-state model is established for the magnesium particle-air mixture.The distribution of the flow field and the influences of factors such as phase transition process,inlet velocity,particle radius and initial particle density on the structure of detonation wave are analyzed numerically under different working conditions.The studies have shown that the process accelerating to the sound speed due to the expansion of the gas phase mainly occurs in the pure evaporation reaction stage of the magnesium particles.The duration of magnesium and magnesium oxide melting accounts for a small proportion of the entire combustion process.Under the initial conditions of normal temperature and pressure,the theoretical maximum temperature in the detonation wave during self-sustaining propagation is lower than the dissociation temperature of the magnesium oxide.The heat absorbed in the magnesium melting process is released into the gas phase for expansion work as the reaction progresses,leading to a small effect of magnesium melting on the structure of the detonation wave.The amount of exothermic heat absorbed in the magnesium oxide melting process is so large that the process of expansion of the gaseous working fluid is almost stopped.Moreover,the absorbed heat cannot be used for gas phase expansion work.Therefore,the melting process of magnesium oxide has a great influence on the structure of the detonation wave.The detonation wave of the magnesium particle-air mixture can be stabilized and selfsustained only at the eigenvalue velocity.Below this value,a singular point appears in the flow field.Above this value,the wave cannot be accelerated to the speed of sound,and the downstream flow field disturbance can pass through the reaction combustion zone and weaken the intensity of the detonation wave.When
作者
刘龙
夏智勋
黄利亚
?马立坤
那旭东
Liu Long;Xia Zhi-Xun;Huang Li-Ya;Ma Li-Kun;Na Xu-Dong(Science and Technology on Scramjet Laboratory,College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China;College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第24期210-220,共11页
Acta Physica Sinica
基金
国家自然科学基金(批准号:51706241,11572349)资助的课题~~
