超低轨航天器气动力分析与减阻设计

轨道降低，航天器受到的气动力增大，气动力对航天器影响显著。考虑自由分子流态 下的超低轨航天器，利用分割法把简单外形的航天器分割为几部分，分别计算各部分的气动 力，然后相加获得总的气动力效果；通过对平面的气动力进行计算分析，提出了超低 轨航天器的减阻设计方法；结果表明：当轨道高度降低到250 km左右时，航天器受到的气动 阻力比500 km高出约2个数量级；一般情况下，超低轨航天器应采用细长体构型，减小迎风 面积；侧面积引起的航天器阻力已经不可忽略，应采用侧面光滑技术，减少侧面阻力；当超 低轨航天器长细比超过一定限度后，随着长细比增大，大气阻力升高。

Aerodynamics Analysis and Reduced Drag Design for the Lower LEO Spacecraft

When the orbit is lower, the aerodynamic force on the spacecraft is higher, so the influence of the aerodynamic force on the spacecraft is biger. We considered the spacecraft in the Free Molecular Aerodynamics, based on the Free Molecular Aerodynamics, calculated the aerodynamics of the spacecraft by the summation of the aerodynamic force of each parts of a simple figure spacecraft. By the calculation of the aerodynamic force of a plane, this article proposed the reduced drag method for a Lower LEO spacecraft. The result shows that: the drag on the orbit of 250 km is almost hundred times than that of 500 km;a leptosomatic figure is preferred for a Lower LEO spacecraft in most cases;the side drag effect can not be neglected and a smooth method is proposed;when limit rate of the length to the radius is passed, the rate is larger, the drag is increased.