基于化学反应动力学耦合G方程的定容弹爆震燃烧研究

Knock Combustion of Constant Volume Bomb Based on Chemical Kinetics Coupling G-equation

由于爆震受多方面的因素共同影响,且这些因素往往是相互耦合在一起,直接在内燃机上对各因素进行解耦进而研究单因素对爆震的影响几乎不可能。针对上述问题,首先基于化学反应动力学和G方程火焰面模型建立了长方体燃烧弹内的爆震燃烧三维CFD模型;然后在该模型基础上把初始压力、初始气温和初始壁温（末端）设为独立变量,系统地研究了各变量对正庚烷与空气混合气的爆震界限及爆震强度的影响。结果表明：当初始压力不高于0.25 MPa时,初始气温和末端壁温在300~700K之间无论如何变化都不会发生爆震;当初始气温不高于450K时,初始压力在0.2~0.5 MPa之间、末端壁温在300~700K之间无论如何变化也都不会发生爆震。同时发现最大压力振幅可作为发生爆震与否的判据,本研究中只要最大压力振幅不高于0.02 MPa即不会发生爆震。

It was extremely difficult to analyze the effect of single factor on knock due to the collective action and mutual coupling of knock influencing factors.For the above problem,a 3DCFD model of knock combustion in a rectangular constant volume bomb was built based on the chemical kinetics and G-equation flame model.Then the influence of single variable such as initial pressure,initial mixture and wall temperature on knock limit and intensity of n-heptane and air mixture was researched systematically.The results show that the knock will not occur when the initial temperature of mixture and wall is between300 Kand 700Kand the initial pressure is lower than 0.25 MPa;and when the initial temperature of mixture is lower than450 K,the initial temperature of wall is between 300 Kand 700Kand the initial pressure is between 0.2 MPa and 0.5 MPa.Besides,the maximum fluctuation amplitude of pressure can be used as knock criterion and its upper limit is 0.02 MPa.