Fault Mechanism Anasysis Of Fan Blade Based On Fluid-structure Coupling

With the development of science and technology,ventilators are widely used in factories,mines,tunnels,cooling towers,ships and buildings and other places.The blade is the key component of the fan.The failure of the blade seriously affects the safe operation of the blade fan.The early crack that has not been diagnosed will continue to expand under the action of lateral vibration.How to use a simple method and a higher Accuracy rate to achieve blade fault diagnosis is the focus of many people’s research.Because of the interaction between the oscillation of the blade itself and the unsteadiness of the excitation flow field,the traditional analysis method can not reveal its essential problem.Based on fluid-solid coupling,the mechanism of flutter and failure of the blade is studied,which has important research significance and application value.Firstly,the dynamic model of the fan blade and the fluid-solid coupling mathematical model are established.The relationship between the fan fluid field and the blade mode and the natural frequency of the blade are obtained.Secondly,the modal test and simulation of the fan blades are carried out to compare the blade frequency and mode variation law of health and crack faults.The law of the interaction between the vibration modes and aerodynamic forces of the blade and the influence of blade crack fault on the vibration mode of each order are studied.Finally,the fluid-solid coupling platform was built by ANSYS Workbench software.The variation of aerodynamic force and blade crack under different speed and wind resistance conditions was simulated and analyzed.The main research contents are as follows:(1)The force analysis of the actual fan blades is carried out to determine the mechanical model and fluid-structure coupling model of the fan blades.(2)Using modal test and simulation analysis,the natural frequency and mode shape of healthy blade and crack fault blade are obtained.The interaction between the aerodynamics of the blade surface and the vibration modes of the blade and the interaction between the location of the crack and the aerodynamic force are analyzed and compared.(3)BladeGen was used to create a fan blade model to analyze the distribution of aerodynamic forces in the fluid field at different speeds and wind pressures.Analyze and compare the aerodynamic distribution of the blade surface to provide a load basis for blade structure analysis.The flow pattern of the fluid field in the ventilator is used to analyze the variation of fluid flow in the fluid field under different parameters.(4)The multi-physics ANSYS simulation software was used to simulate the distribution of stress,strain and total deformation between healthy blades and crackedblades of different fans under different wind pressures.Through simulation analysis,the influence of crack on blade strain and stress and the expansion trend of blade crack are studied.