Research On Multi-objective Optimization Methods And Their Applications To Hypersonic Test Vehicle

With the development of hypersonic air-breathing propulsion theory, hypersonic flight test is becoming an important direction for validating all kinds of hypersonic vehicles'performance indexes in complex flight atmosphere. Therefore, the design of hypersonic test vehicle with optimal performance indexes is commonly the key factor to maintain test reliability and success rate, so the multi-objective optimization problem in the process of system analysis and design has also been drawn attention by many researchers in aerospace design domain. This dissertation, focusing on the optimal design of hypersonic test vehicle based on various conflicting objectives, explores multi-objective optimization methods and their applications systematically and comprehensively. The results attainted are as followed.(1) On the basis of multi-objective evolutionary schemes and strategies, common MOEA algorithms and some kinds of test functions are expounded in detail, as well as their performance assessment methods of multi-objective optimizers.(2) Multi-Objective Particle Swarm Optimization algorithm (MOPSO) is studied thoroughly. Aiming to solve out the pre-mature convergence phenomenon, the chaos mutation is introduced into PSO for improving global optimal ability. Then, taking advantage of MOPSO algorithm with chaos mutation and no mutation, a kind of grouped MOPSO algorithm is proposed to tackle the problem of converging to local optimal region in the process of evolutionary calculation. For lessening their conflicts between diversity and convergence, a new improved MOPSO algorithm based on angle coordinate parameters and auxiliary fitness value is studied to maintain convergence indexes in the premise of good diversity for Pareto solutions.(3) Pareto Solutions and relative boundary are analyzed. Firstly, the preference function model is established with various design rules. Then, an improved method based on Pareto sensitivity analysis is proposed to increase the number of candidate set. Finally, the multi-objective decision making method based on multi-object-value loss is proposed with robust design analysis by the index of objective-value-loss, validating its rightness and effectiveness by the example of satellite appendix control system.(4) Some researches on hypersonic test vehicle's multi-objective optimization design are carried out. Firstly, the overall design plan of low-cost hypersonic test flight is established, including the system function, indexes and configuration components. Secondly, the multi-objective optimization problem of hypersonic test vehicle is analyzed including the necessity and solving methods for multi-objective evolution. Lastly, the minimum takeoff mass and the maximum range of hypersonic free-flight period is considered as objective functions to carry out multi-objective evolutionary calculation on the basis of multidisciplinary knowledge such as propulsion model, aerodynamic calculation, ballistic calculation, structure and mass model. And the multi-objective optimization design and decision analysis to hypersonic test vehicle is carried out deeply, improving its necessity and reasonability for multi-objective optimization design.(5) In the light of engineering practical problem, the uncertain multi-objective optimization design for hypersonic test vehicle is investigated in this dissertation. Based on uncertain multi-objective optimization theory, the multi-objective optimization model of hypersonic test vehicle in the presence of uncertainty is established when considering all kinds of uncertain factors in multidisciplinary knowledge. And the robust ultimate design plan is ascertained by means of UC-IMOPSO algorithm with probability dominating relationship. Moreover, for the purpose of larger ballistic parameter deviations deriving from unguided flight motion, a new altitude-correction algorithm is proposed, which has increased hypersonic vehicle flight probability in the range of nominal working dynamic pressure.The research of this dissertation is a typically application of multi-objective optimization problem, which could provide some relative analysis and demonstrating methods for other aerospace vehicle systems with different flight mission.