火星进入的气动力特性预测模型分析

Model Analysis for Predicting Aerodynamic Characteristics of Mars Entry

针对火星探测器的高超声速进入问题,利用三维并行程序求解流体力学Navier-Stokes方程,分别考虑真实气体模型和完全气体模型,分析模型及参数对气动力特性预测的影响,旨在得到准确、高效和可靠的火星进入器气动力特性预测模型.采用真实气体模型对海盗号进行了沿飞行轨道的数值模拟,气动力特性预测结果与飞行数据一致,验证了火星大气热化学模型及数值方法.分别采用真实气体模型和完全气体模型对海盗号升力式进入和探路者号零攻角进入进行了气动力特性预测,结果表明采用等效比热比的完全气体模型的预测值非常接近真实气体模型,偏差均在1%左右,配平攻角相差约0.4°,来流比热比模型的气动力特性预测值偏差很大.火星进入器的气动力预测建议采用真实气体模型和等效比热比完全气体模型.

Martian atmosphere which is quite different from Earth atmosphere plays an important role for Mars entry vehicles. Therefore aerodynamic predictions for trajectory design and layout optimization should be settled firstly. Three-dimensional Navier-Stokes equations with real gas model and ideal gas model have been solved by a parallel code to analyze the impact of different models on aerodynamic characteristics, to obtain accurate, efficient and reliable model for aerodynamic predictions. The good agreement among the numerical results, the reference values and the flight data of Viking along the trajectory validates the real gas physical-chemical models and the numerical methods applied. Using real gas model and ideal gas model, aerodynamic characteristics of lift-entry Viking and zero angle of attack Mars Pathfinder have been predicted. The results show that predicts value of ideal gas model with effective specific heat ratio is very close to that of the real gas model, the deviation is about 1%, and the difference of the trim angle of attack is about 0.4°. Prediction of ideal gas with specific heat ratio from inflow temperature shows a large deviation. Real gas model and ideal gas model with effective specific heat ratio are suggested in aerodynamic characteristics predictions of Mars entry.