基于边界层燃烧方法的宽速域飞行器内流道减阻研究

Drag Reduction by Boundary Layer Combustion on Internal Flowpath in a Wide-Range Mach Numbers Vehicle

关键词:  宽速域飞行器  内流  减阻  低燃点燃料  边界层燃烧  数值模拟

Key words:  Wide-range Mach numbers vehicle  Internal flow  Drag reduction  Low ignition temperature fuel  Boundary layer combustion  Numerical simulation

摘要:

为了降低宽速域飞行器的内流阻力，基于边界层燃烧方法，分析了系列进口马赫数条件下二维扩散段总阻力中摩阻和压阻的特性，研究了不同进口马赫数下摩阻和压阻分量对总减阻的贡献、燃烧影响区域和壁面热流密度，探讨了喷射参数对减阻效果的影响，探索了边界层燃烧方法在典型混压式进气道中的减阻应用。结果表明，随着进口马赫数的增加，总阻力中摩阻分量随之增加；边界层燃烧对摩阻和压阻减阻的机理有所不同，壁面附近流场特性变化使得摩擦系数减小，燃烧局部增压对壁面产生的增推效果使得压力系数减小；从总内阻减阻百分比看，在相同燃料/空气当量比下，低马赫数工况下边界层燃烧减阻效果不如高马赫数工况，且在低马赫数工况下，喷嘴附近壁面热流密度会显著增加；在本文所研究的参数范围内，摩阻和压阻对当量油气比更为敏感，而对喷射方向和喷射速度不敏感。

Abstract:

In order to reduce the internal flow drag of wide-range Mach numbers vehicle， based on boundary layer combustion， the characteristics of friction and pressure components in the total drag of two-dimensional diffusion section at a series of inlet Mach numbers are analyzed. The contribution of the friction and pressure components in the total drag reduction， the combustion influence domain， and the heat flux on the wall surface at different inlet Mach numbers are investigated. The effects of the injection parameters on the internal drag reduction are discussed. The effects of drag reduction by boundary layer combustion in a designed supersonic mixed compression inlet are explored. The results indicate that with the increase of inlet Mach number， the friction drag component in the total drag increases. The friction drag reduction mechanism mainly depends on the change of the flow characteristics in the boundary layer. The pressure drag reduction is mainly caused by the effect of the thrust enhancement by boundary layer combustion. From the view of total internal drag reduction， the effect of the internal drag reduction at lower Mach number condition is not as good as that at higher Mach number condition for the same fuel/air equivalence ratio. Furthermore， it is also found that at lower Mach number condition， the wall heat flux will increase significantly， which needs to be paid a special attention. For the parameters’ scope investigated in this paper， the friction drag and the pressure drag are more sensitive to the fuel/air equivalence ratio， but not to the injection direction and velocity.