Isogeometric Analysis Of Fluid-structure Interaction And Shape Optimal Design Of Turbine Blade

Turbine blade is the core component of aero-engine,and it always bears the aerodynamic load.The service environment of blade is complex,and the mechanical analysis problem is a typical fluid-structure interaction problem.With the development of aerospace industry,the design and performance requirements of turbine blade are more and more stringent.Once the blade fails,it will cause great losses.How to efficiently and accurately carry out mechanical analysis and optimal design of turbine blade is a very important topic.As a new numerical simulation method,the isogeometric analysis integrates structural modeling and mechanical analysis into a unified mathematical framework,which provides a new tool for multiphysics analysis and optimum structural design.Besides,isogeometric analysis abandons the traditional approximate discretization process of finite element analysis,which can improve the computational efficiency and reduce the calculation cost.The fluid-structure coupling and optimization design based on finite element analysis has the characteristics of difficult mesh generation and complicated calculation process.Therefore,it has important research significance to make full use of the advantages of isogeometric analysis for fluid-structure interaction and shape optimization of turbine blade.In this thesis,the service environment load of aeroengine turbine blade is considered.Aiming at the three-dimensional turbine blade and two-dimensional profile,the fluid-structure interaction computing and two-dimensional shape optimization of turbine blade are carried out based on isogeometric analysis.Firstly,using spline curve to fit blade profile coordinate points according to blade aerodynamic data,the parametric model of twisted turbine blade was built by UG,which laid the foundation for structural analysis and shape optimization design.The two-dimensional fluid field and the three-dimensional solid field of turbine blade are computed respectively based on isogeometric analysis.The nonlinear equations of fluid are solved by Newton-Raphson method.The pressure,velocity in the fluid domain and the displacement,stress in the solid domain are obtained,which are basically consistent with the results of finite element analysis.Based on the parametric model,the velocity and pressure in the fluid domain and the stress of the blade under the fluid-structure interaction are calculated by using one-way coupling.The coupling data transfer errors between isogeometric analysis and finite element analysis are compared,and the advantages of the fluid-structure interaction data transfer based on the isogeometric analysis are expounded.Then,the shape optimization of two-dimensional profile based on isogeometric analysis is carried out,and the profile with smaller deformation under aerodynamic load is obtained.The sensitivity analysis formula based on isogeometric analysis is derived,and shape optimization of cantilever beam under concentrated load and uniform load is carried out by using Method of Moving Asymptotes(MMA).The results are consistent with those in the literature,and the correctness of the program is verified.In the part of profile optimization,the displacement of the contact point between the profile and the blade edge is taken as the objective function,and the control point on the blade back is set as the design variable.The shape optimization design is carried out under the uniform load and the real fluid-structure interaction respectively,and the optimization results can be directly converted into IGES file for display.The results show that the shape of the profile can be easily changed by taking the control points as the design variables,which saves the interaction between the analysis model and the physical model and makes the calculation more efficient.