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针对液体火箭发动机真空比冲基本不变,火箭基循环组合发动机(RBCC)比冲随着飞行条件不断变化的特点,提出了将增广拉格朗日遗传算法优化第一级飞行弹道与传统液体火箭质量估算方法估算第二级起飞质量相结合,获得水平起飞两级入轨RBCC-RKT飞行器第一级起飞质量的估算方法,为总体方案初步设计论证提供参考.通过算例,分析了一级RBCC飞行器惰性质量比、最高动压,气动特性与起飞质量之间的关系.计算表明,降低RBCC飞行器惰性质量比、提高一级飞行器最大飞行动压、提高飞行器升阻比,都能有效地降低一级起飞质量. 相似文献
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《中国航空学报》2022,35(9):208-225
Accurate prediction of sonic boom is one of key challenges for the design of a low-boom supersonic aircraft. For most of available far-field prediction methods, the effect of atmospheric turbulence appearing in the planetary boundary layer cannot be considered, which results in remarkable inaccuracy of predicting ground-level sonic boom waveform. Although some efforts have been made to overcome the shortcoming, the turbulence effects are not yet well described so far. This article proposes an improved method by extending the two-dimensional Heterogeneous One-Way Approximation for the Resolution of Diffraction (HOWARD) equation to account for the axial and transverse convections of wind fluctuation as well as the effect of temperature fluctuation. The proposed method is validated by comparing the predictions with the flight-test data of JAXA D-SEND#1 LBM, which shows that the result of the proposed method is in better agreement with the flight-test data than that of the method without considering atmospheric turbulence effects. Then, distortion mechanism of sonic boom waveforms caused by atmospheric turbulence is analyzed by using the proposed method. It is indicated that the effect of turbulent convection makes uniform sonic-boom wavefronts irregular, which creates the condition of diffraction effect to perturb waveforms. Finally, the proposed method is applied to investigate the behavior of two types of waveforms given by the sonic boom minimization theory. Results show that a far-field waveform with a weaker initial shock is more beneficial for low-boom design of a supersonic aircraft. 相似文献