气动力辅助椭圆轨道转移技术研究

研究了两种共面椭圆轨道最优转移方法--基于单纯推力的双脉冲对称转移和基于气动力辅助变轨技术的协同机动方法。推导了双脉冲对称转移问题中转移椭圆轨道的求解公式，采用遗传算法求解最优变轨点位置，给出了变轨脉冲的计算方法。将气动力辅助对称转移过程分为3段：真空飞行段、大气飞行段、真空飞行段。以能量最小为性能指标，将大气飞行段轨迹优化问题转化为标准最优控制问题模型，并利用Gauss伪谱法进行求解，得到“巡航+滑行+巡航+滑行”的大气最优飞行轨迹。最后对两种转移方法进行详细比较，指出初始椭圆轨道近地点越接近大气层，气动力辅助对称转移方法比双脉冲对称转移方法越节省能量。

Research on Aeroassisted Orbital Transfer between Elliptical Orbits

Two kinds of coplanar elliptic orbital transfer methods were studied: two-impulse symmetric transfer using pure rocket propulsion and synergetic maneuver using aeroassisted orbital transfer technology.For the problem of two-impulse symmetric transfer,the formula for solving elliptical transfer orbit was derived.Then the optimal position of orbit changing was obtained by genetic algorithm,and the characteristic velocity was given.The process of aeroassisted symmetric transfer was divided into three parts,including vacuum flight portion,atmospheric flight portion,and vacuum flight portion.Assuming the minimum-fuel as performance index,trajectory optimization during atmospheric flight was transformed into standard optimal control model and was solved by Gauss pseudospectral method.The optimal atmospheric flight trajectory was "aerocruise+aeroglide+aerocruise+aeroglide".Finally,detailed comparisons were carried out for the two methods.The results show that when the perigee of initial elliptic orbit is more close to atmospheric boundary,aeroassisted symmetric transfer is more predominant than the two-impulse symmetric transfer.