Research On Helicopter Preliminary Design And Optimization

The application of Database and Multi-Objective/Multidisciplinary Design Optimization tohelicopter conceptual/preliminary design is researched in this thesis.As the rapid development of aviation technology and the growing complexity of aerial systems,the concept and patterns of modern aircraft design have a great change that from focusing on flightperformances to focusing on the aircraft system effectiveness, from serial/iterative design pattern toparallel/integrative design pattern. Meanwhile, the early stage of aircraft design such as conceptualdesign and preliminary design is getting more and more important. Helicopter is a large complexsystem and conceptual design is the most important stage in helicopter research as it has an overallinfluence. According to the features and Multidisciplinary connection of helicopter preliminary design,the application of Helicopter Preliminary Parameter Database and Artificial Neural Networks tohelicopter conceptual design stage is researched, and the Multidisciplinary Design OptimizationFramework integrating with several subsystem analytical models is established to explore the efficacyof Multidisciplinary Design Optimization to helicopter preliminary design stage. The main contents ofthe thesis are as followings.The Helicopter Preliminary Parameter Database and Group Weight Database are built to collectmost helicopters in the world. After the selection, input and fixing data, a helicopter concept designmethod based on Regression Analysis and Artificial Neural Networks is established to analysis theparameters of group weights, main rotor, tail rotor, fuselage and power plant. A set of simplifiedalgorithms and neural networks are obtained to estimate helicopter overall parameters.The model of flight performance suitable for helicopter preliminary parameter optimization is setup to analysis the helicopter basic flight performance including hover, climb and level flight. Animproved rank-density-based multi-objective genetic algorithm with solution strategies such asreal-coded, tournament selection, elitism preservation and adaptive operators is developed to find anear-optimal, near-complete, uniformly distributed Pareto front. Based on this genetic algorithm,helicopter model of flight performance is optimized with a set of optimal solutions to helpdecision-making efficiently and accurately.A free wake model with Wessinger-L lifting surface and PIPC solution is set up with anappropriate precision in blade aerodynamic shape optimization and the less time consuming at thepreliminary design stage. As the optimization goal of minimizing the rotor required power in bothhover and level flight status, parallel computing technology and surrogate model of neural networks are applied to the improved multi-objective genetic algorithm to reduce time consuming and improvethe efficiency and quality.Based on the establishment and validation of helicopter group weight, flight performance, rotoraerodynamic shape, stability and control and maneuverability, the data flow and connections areanalyzed and the helicopter conceptual/preliminary multidisciplinary design optimization model is setup.As the characteristics of helicopter conceptual/preliminary multidisciplinary design optimizationmodel and the bad convergence and large computation of regular collaborative optimization method,the Multi-Objective Collaborative Optimization method with surrogate model is presented in thisthesis. UH-60A helicopter is taken as the example to show the feasibility and effectiveness comparingwith multidisciplinary feasible method. Finally, referring to AH-64attack helicopter, conceptualdesign of a new attack helicopter is undertaken according to the design requirements. Based on thisconceptual design, helicopter preliminary multidisciplinary design optimization with CombatEfficiency Index as the composite indicator is carried out. The results show that the helicopterconceptual/preliminary multidisciplinary design optimization framework can be effectively applied tooptimize helicopter design parameters, able to improve efficiency and quality.