摘要
就高超声速再入体尾迹等离体场而言，为进行其亚密湍流雷达散射截面的理论分析，提出了计算湍流尾迹脉动等离子体场强的理论模型及求解方法，即在研究高超声速尾迹流动特征的基础上，推导，使用包括化学组份浓度脉动强度的ｋ－ε－ｇ湍流模型，用以封闭高超声速粘性尾迹湍流运动时均控制方程组，并用全隐式有限差分法求解，算例小钝锥体的飞行条件为零攻角，Ｍ∞＝２１．３，Ｒｅ∞Ｄ＝１．３３×１０＾６，Ｍ∞＝２０．５。
For analysis of radar cross section (RCS) of hypersonic underdense turbulent ware of reentry vehicles, a theoretical method for calculating the plasma fluctuation intensity is developed based on analysis of the characterization of the hypersonic wake flow. In the method k-ε-g turbulent model is adopted to complete Reynolds equation, in which the chemical component fluctuation intensity is taken into account. The governing equations are solved by fully implicit finite-difference schemes. For calculating RCS, the single-electron multiple-scattering model──distorted wave Born approximation is used. As an example the turbulent wake flow field and the RCS of a small blunt cone are computed in which M_∞ = 21.3 and 20.5, Re_(∞D) = 1.33 × 10~6 and 3.22 × 10~5. The present computational results are mainly as follows:The characteristic parameters of flow field on the centerline and along radial direction in the wake, such as velocity, temperature, electron number density, turbulent energy, dissipation,electron concentration fluctuation intensity and so on, are obtained. The distributions of these calculated quantities are reasonable.The effects of turbulent fluctuation on the now field parameters are remarkable in a relatively short distance after the transition point, but become weaker quickly downstream so that they may be neglected in computation for the far wake.The variations of RCS with sight angle in different region of the scattering background flow field, under various polarization states are given by the present work, which aie consistent with previous theoretical analysis[3].The present calculated results have also shown that for the body shape and flying conditions used in this paper, after appropriately selected scale of turbulent eddy, the RCS can be approximately predicted baized on the weak fluctuation hypothesis, i.e. By the method,the difficulty of solving the fluctuation equations can be circumvented.
出处
《力学学报》
EI
CSCD
北大核心
1999年第4期434-441,共8页
Chinese Journal of Theoretical and Applied Mechanics
关键词
高超声速
再入体
湍流尾迹
雷达散射截面
hypersonic reentry vehicle, turbulent wake, radar cross section (RCS), electron fluctuation intensity
