综合热力学模型的平流层飞艇上升轨迹优化

针对平流层飞艇的上升轨迹优化问题,综合热力学模型进行了研究.主要分析了飞艇基本热力学行为,研究了蒙皮及内部气体的能量方程并建立了详细的飞艇动力学和运动学模型.在热力学、动力学和运动学分析的基础上,建立了以飞行时间为优化目标的平流层飞艇的轨迹优化模型.利用直接配点法将轨迹优化问题转化为非线性优化问题,再通过非线性求解器SNOPT(Sparse Nonlinear Optimizer)对不同场景的问题进行最优化轨迹求解.优化结果表明:热力学效应对优化轨迹有较大影响,在上升过程中,太阳能辐射为主要影响因素,另外风场也对换热量有一定影响.

Ascent trajectory optimization for stratospheric airships with thermal effects

In respect for ascent trajectory optimization of stratospheric airship,a research was conducted with the thermal effects.Basic thermal characteristics of the stratospheric airship and the energy equations about the ship film and the internal gas were introduced.Besides,the equations of motion for the airship were described in detail.To minimum the flight time,a trajectory optimization problem was constructed and then converted into a parameter optimization problem by a direct collocation method.In different scenarios,the optimal trajectories were developed by a numerical nonlinear solver,sparse nonlinear optimizer(SNOPT).It shows that the solutions are greatly affected by the thermal behaviors.Solar irradiation is the most important factor during ascent,and in addition,the natural wind also affects the thermal transfer of convection.