两相爆震波爆燃向爆震转变过程的数值模拟

Numerical Simulation of Deflagration to Detonation Transition of Two-phase Detonation Wave

针对液态辛烷/空气两相混合物燃烧波在一维封闭空间内传播的爆燃向爆震转变(DDT)问题,运用化学反应流动基本理论、颗粒轨道模型和两步反应模型,在拉格朗日质量坐标系中建立了对该现象的数学表达,并开发了数值模拟程序CT-PD,其中气体动力学方程采用显式Sαγ,β差分格式,化学反应项使用二阶精度的Adams方法。通过数值模拟研究了液态燃料爆震波在爆震管内发生、发展、传播及其特性参数变化特点。研究发现在两相爆震中,由于油滴蒸发吸热及阻力作用,致使爆震波峰值压力及爆震波速等特性参数低于理论值。研究中将数值模拟结果与实验波形进行了比较,发现两者符合良好,说明计算方法是可行的。

Mechanism of Deflagration to Detonation Transition （DDT） of liquid octane/air mixture is studied by using the theory of one - dimension reaction flow, particle - trajectory model and two - step reaction model, of which the numerical formulation is described on the S^γα,β scheme of“gasdynamic” step and a second - order accurate Adams method of“chemical” step in Lagrangian mass coordination system, based on which code - CPTD is developed. The paper investigates numerically the generation, evolution, propagation and basic properties of liquid - fueled detonation structure. Simulations reveal that due to latent heat of vaporization required and drag force of fuel droplets the characteristic parameters of two phase detonation wave, such as peak pressure and propagation velocity are below theoretical values. It＇s found that the numerical results are in good agreement with experimental ones, which shows that a feasible numerical method has been provided here to simulate pulse detonation engine operation processes including DDT phenomena.