来流温度对气动热的影响及关联方法初步研究

Preliminary study on the influence of freestream temperature on aeroheating and correlation method

  • 摘要: 边界层底层温度梯度是造成气动热的重要原因,而边界层底层恢复温度和壁面温度直接影响边界层底层温度分布。为提升地面风洞低总温环境下气动热实验数据外推预测真实飞行高总温环境下气动热的预测精度,首先基于无量纲N−S方程推导了层流和湍流流态下气动热的主要影响参数;然后针对高超声速飞行器标模外形,在相同马赫数、雷诺数条件下,分别开展固定壁温/壁温比的数值模拟,对比分析了来流温度对气动热系数的影响规律;最后基于边界层近似解理论,分别针对层流和湍流流态建立了考虑当地边界层外缘参数影响的气动热关联换算方法,并在不同温度条件下,对量热完全气体假设下的气动热计算结果开展了关联换算。

     

    Abstract: The temperature gradient at the bottom of the boundary layer is a significant factor causing aeroheating, and both the near-wall recovery temperature and wall temperature directly influence the temperature distribution at the bottom of the boundary layer. To enhance the extrapolation accuracy of aeroheating predictions from ground wind tunnel tests under low total temperature conditions to real-flight high total temperature environments, the primary influencing parameters for aeroheating in both laminar and turbulent flow regimes are derived based on dimensionless Navier−Stokes equations. Subsequently, for a standard hypersonic vehicle configuration, numerical simulations are carried out under identical Mach number and Reynolds number by separately fixing wall temperature and wall-to-freestream temperature ratio. The influence of freestream temperature on aeroheating coefficient is compared and analyzed. Finally, based on the boundary layer approximate solution theory, aeroheating correlation and conversion methods accounting for the influence of local boundary layer outer edge parameters are developed separately for laminar and turbulent flow regimes. At different temperatures, the aeroheating results computed under the calorically perfect gas assumption are respectively correlated and converted.

     

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