强迫对流下硼颗粒燃烧特性影响因素研究

针对冲压发动机燃烧室内强迫对流下的硼颗粒燃烧特性展开了系统研究,考虑气相流动、扩散和表面单步有限化学反应动力作用,建立了强迫对流下硼颗粒燃烧过程的物理和数学模型;采用有限体积法求解含多组分反应流的二维轴对称Navier-Stokes方程,并验证了数值仿真方法的正确性。首先通过数值仿真研究了来流速度、颗粒半径、环境中氧气质量分数和环境压力等因素对硼颗粒燃烧特性的影响,并对其成因展开了详细分析。研究表明,在强迫对流作用下,硼颗粒总的燃烧质量流率和质量流率通量均随来流速度、颗粒半径、环境中氧气质量分数和环境压力的增加而增大。通过深入分析发现,强迫对流下硼颗粒的燃烧质量流率通量随着来流雷诺数的增加而增大。然后基于大量数值仿真结果,对相对静止气氛下的硼颗粒质量流率通量进行了修正,用于描述强迫对流下的硼颗粒燃烧特性。

Influencing factors of combustion characteristics of boron particle in forced convective flow

The combustion characteristics of single boron particle in forced convective flow in ramjet engines are investigated systemically. A physical and mathematical model is proposed taking into consideration the gas flow around the particle, the gas diffusion and the surface finite reaction dynamics. The two-dimensional axi-symmetric Navier-Stokes equations with species reactions are solved using the finite volume technique. And the numerical simulation method is validated. Then influencing factors such as the free stream velocity, particle radius, the ambient oxygen mass fraction and the ambient pressure on the combustion characteristics of single boron particle are studied by numerical simulations. And the effect mechanism for each factor is analyzed in detail. The numerical prediction results show that in forced convective flow, both the mass rate and the mass flux of the buring boron particle increase with the increase in the free stream velocity, the particle radius, the ambient oxygen mass fraction and the ambient pressure. A comprehensive analysis of the results is conducted and it is found that the mass flux of the buring boron increases with the stream Reynolds number. Then the mass flux of the buring boron particle in the static atmosphere is modified based on abundant numerical results to describe the combustion characteristics of the boron particle in forced convective flow.