The Analysis Of The Rule About Variable Sweep Wing-Body

Variable-sweep wing can make the performance both in high and low speed,improved the performance both the economic efficiency and the operational mission.How to determine the angle attack in the range of different height.The speed is the key of optimal variable sweep,named swept-back rules.In this paper,in order to find the best target for variable-sweep rules.Designed a variable-sweep wing body model and based on CFD, calculated its aerodynamic characteristics. Combined with calculation tools, MATLAB, and the standard genetic algorithm, get the optimal height under specified variable-sweep rules. Through the calculation and analysis the results in different height, get the final conclusion. The specific content are as follows:Firstly, variable-sweep wing body is proposed,based on the research of the variable-sweep technological achievements at home and abroad, and established five models on CATIA. GAMBIT is used to do grid breakdown of wing-body model,boundary conditions are set, then provide the calculation for the latter work.Numerical simulation was done by FLUENT, and get the aerodynamic characteristics of the variable-sweep wing. Compares of the aerodynamic characteristics at different speeds, and find the reason.Then,used genetic algorithm to optimize the calculation results in the global scope, best lift to drag ratio was the constraint conditions, then got curve of optimal sweep angle versus Mach in the specify height.Finally, calculated aerodynamic performances in different altitude and analysis comparative the results, for analysis influence of altitude on the law of optimal variable swept, to obtain the law of optimal variable swept under different altitude and velocity. And comparative analysis with other variable sweep aircraft aerodynamic performances, verified the reasonableness of obtained law of variable swept indirectly.The results of the research show that:the rule curve of optimal sweep and angle of attack t with Mach number, based on finding the best result in global optimization for variable-sweep wing body by genetic algorithms, is reasonable. The optimal sweep gently increases with increasing speed in a range of small Mach numbers and low altitude. Angle of attack is a sinusoidal curve growth in small range of Mach numbers and regardless of the height.the optimal sweep rises sharply in range of largeMach numbers and high altitude. In range of large Mach numbers, the angle of attack keep the initial curve unchanged at low altitude and then increases sharply in altitude.The targets of driving with flying wing resistance variable-geometry can be achieved by designing reasonably flexibility drive mechanism-based a preferred variant derived swept law.