Trajectory optimization of morphing aircraft based on multi-fidelity model

基于变精度模型的变外形飞行器弹道优化

¹ School of Astronautics, Northwestern Polytechnical University, Xi’an 710072, China
² Jiangxi Hongdu Aviation Industry Group Co., Ltd, Nanchang 330024, China

Received: 18 June 2021

Abstract

Morphing aircraft can flexibly change its aerodynamic shape to adapt to the varying flight conditions during a flight. Compared with the traditional fixed shape aircraft, it has a very obvious advantage. This paper proposed a solution flow based on the multi-fidelity model for the morphing aircraft with morphing wings, and the optimal trajectory and morphing rules are studied. The angle of attack, Mach number, sweep angle and axial position of the morphing wing are defined as variables for generating training data for building the multi-fidelity Kriging model, which is used to predict the aerodynamic performance of the aircraft. Based on the hp-adaptive pseudospectral method, the model is used as aerodynamic input to establish the optimization process of morphing rules, and the trajectory optimization is carried out for the contrast fixed wing aircraft and morphing aircraft with the goal of minimum fuel consumption, respectively. The control parameters such as morphing parameters, angle of attack and engine control parameters are optimized simultaneously while meeting the flight mission requirements. The results show that the morphing aircraft has higher climbing and descending efficiency, and the optimal trajectory has obvious advantages. Moreover, the research flow proposed in this paper is universal, which can effectively reduce the CFD calculation cost and improve the efficiency of trajectory optimization of the variable shape vehicle.

摘要

变外形飞行器在飞行过程中可以根据需要灵活改变自身的气动外形以适应飞行条件的变化, 与传统的固定外形飞行器相比, 具有非常明显的优势。针对一种机翼后掠角和轴向位置可改变的变外形飞行器, 提出了基于变精度模型的求解流程, 并对其最优弹道和变形规律进行了研究。将攻角、马赫数、后掠角和机翼轴向位置定义为生成训练数据的变量, 建立了满足精度条件的变精度Kriging模型来预测飞行器的气动性能。将该模型作为hp自适应伪谱法的气动输入, 建立了变形规律优化求解流程, 并分别对固定翼飞行器和变外形飞行器以最少燃料消耗为目标进行弹道优化。在满足飞行任务要求的同时, 实现了变形参数、攻角和发动机控制参数等控制量的同时优化, 结果表明变外形飞行器的爬升、下降效率较高, 最优弹道具有明显的优势。同时, 所提出的研究流程具有通用性, 可以有效降低变外形飞行器的CFD计算成本, 提高变外形飞行器弹道优化效率。