The aim of this paper is to present a finite element modeling of the dynamic motion of a turbine rotor and its controller design with the mass unbalance under a crack on a rotating shaft. This process is an advanced m...The aim of this paper is to present a finite element modeling of the dynamic motion of a turbine rotor and its controller design with the mass unbalance under a crack on a rotating shaft. This process is an advanced method to the mathematical description of a system including an influence of a mass unbalance and a crack on the rotor shaft. As the first step, the shaft is physically modeled with a finite element method and the dynamic mathematical model is derived by using the Hamilton principle;thus, the system is represented by various subsystems. The equation of motion of a shaft with a mass unbalance and a crack is established by adapting the local mass unbalance and stiffness change through breathing and gaping from the existence of a crack. This is a reference system for the given system. Based on a fictitious model for transient behavior induced from vibration phenomena measured at the bearings, an elementary estimator is designed for the safety control and detection of a mass unbalance on the shaft. Using the state estimator, a bank of an estimator is established to get the diagnosis and the system data for a controller.展开更多
In order to overcome the efficiency problem of the conventional gradient-based optimal design method,a highly-efficient viscous adjoint-based RANS equations method is applied to the aerodynamic optimal design of hover...In order to overcome the efficiency problem of the conventional gradient-based optimal design method,a highly-efficient viscous adjoint-based RANS equations method is applied to the aerodynamic optimal design of hovering rotor airfoil.The C-shaped body-fitted mesh is firstly automatically generated around the airfoil by solving the Poisson equations,and the Navier-Stokes(N-S)equations combined with Spalart-Allmaras(S-A)one-equation turbulence model are used as the governing equations to acquire the reliable flowfield variables.Then,according to multi-constrained characteristics of the optimization of high lift/drag ratio for hovering rotor airfoil,its corresponding adjoint equations,boundary conditions and gradient expressions are newly derived.On these bases,two representative rotor airfoils,NACA0012 airfoil and SC1095 airfoil,are selected as numerical examples to optimize their synthesized aerodynamic characteristics about lift/drag ratio in hover,and better aerodynamic performance of optimal airfoils are obtained compared with the baseline.Furthermore,the new designed rotor with the optimized rotor airfoil has better hover aerodynamic characteristics compared with the baseline rotor.In contrast to the baseline airfoils optimized by the finite difference method,it is demonstrated that the adjoint optimal algorithm itself is practical and highly-efficient for the aerodynamic optimization of hover rotor airfoil.展开更多
文摘The aim of this paper is to present a finite element modeling of the dynamic motion of a turbine rotor and its controller design with the mass unbalance under a crack on a rotating shaft. This process is an advanced method to the mathematical description of a system including an influence of a mass unbalance and a crack on the rotor shaft. As the first step, the shaft is physically modeled with a finite element method and the dynamic mathematical model is derived by using the Hamilton principle;thus, the system is represented by various subsystems. The equation of motion of a shaft with a mass unbalance and a crack is established by adapting the local mass unbalance and stiffness change through breathing and gaping from the existence of a crack. This is a reference system for the given system. Based on a fictitious model for transient behavior induced from vibration phenomena measured at the bearings, an elementary estimator is designed for the safety control and detection of a mass unbalance on the shaft. Using the state estimator, a bank of an estimator is established to get the diagnosis and the system data for a controller.
文摘In order to overcome the efficiency problem of the conventional gradient-based optimal design method,a highly-efficient viscous adjoint-based RANS equations method is applied to the aerodynamic optimal design of hovering rotor airfoil.The C-shaped body-fitted mesh is firstly automatically generated around the airfoil by solving the Poisson equations,and the Navier-Stokes(N-S)equations combined with Spalart-Allmaras(S-A)one-equation turbulence model are used as the governing equations to acquire the reliable flowfield variables.Then,according to multi-constrained characteristics of the optimization of high lift/drag ratio for hovering rotor airfoil,its corresponding adjoint equations,boundary conditions and gradient expressions are newly derived.On these bases,two representative rotor airfoils,NACA0012 airfoil and SC1095 airfoil,are selected as numerical examples to optimize their synthesized aerodynamic characteristics about lift/drag ratio in hover,and better aerodynamic performance of optimal airfoils are obtained compared with the baseline.Furthermore,the new designed rotor with the optimized rotor airfoil has better hover aerodynamic characteristics compared with the baseline rotor.In contrast to the baseline airfoils optimized by the finite difference method,it is demonstrated that the adjoint optimal algorithm itself is practical and highly-efficient for the aerodynamic optimization of hover rotor airfoil.
