Research On Fluid-Solid-Thermal Coupling Characteristics Of Gas Turbine Ejector Valve Mechanism

In the trend of pursuing high-performance aero-engine and gas turbine,all kinds of motion regulating mechanisms play an important role in improving the performance of the whole machine.The motion adjustment mechanism with various forms and functions bears the coupling effect of complex loads such as aerodynamic,thermal,centrifugal force,vibration and so on in the working process.The failure problem becomes more and more obvious,which threatens the normal operation of the engine.Only considering the calculation and verification of the above load action,it is not in line with the actual working conditions of the engine,nor can it meet the design requirements of the new generation engine.It is important to carry out the multi field coupling characteristics analysis of the typical motion adjustment mechanism for the flow field design and strength design of the engine.In this paper,the fluid solid thermal coupling characteristics of a gas turbine exhaust ejector valve mechanism are studied,including the flow characteristics of the ejector flow field,the motion characteristics of the mechanism,the structural mechanical characteristics,the vibration characteristics,and the data transmission of the coupling interface.The fluid-solid-thermal coupling analysis method described in this paper can also be used for the typical motions of the stator regulating mechanism,nozzle,backstepping and so on It provides a reference for the strength analysis and structure optimization of the mechanism.The main research contents are as follows:(1)In order to analyze the flow characteristics of the ejector,based on the continuity equation,energy conservation law,Bernoulli equation and perfect gas equation of state,the general equation of one-dimensional ejector is derived,and the influencing factors of outlet pressure are obtained.According to the structure and working principle of the valve mechanism,the movement law of the valve plate is analyzed,and the relationship between the displacement of the input slider and the rotation angle of the output valve plate is obtained;(2)Taking a gas turbine exhaust ejector as the research object,in order to analyze the variation law of internal pressure and temperature of the ejector,the correctness of the steady-state simulation method is verified by comparing with the literature results.According to the actual structure,the flow field model of the ejector is established,the steady-state and transient solutions of the flow field model of the ejector are carried out,and the changes of temperature and pressure in the flow field during the movement of the valve are obtained law;(3)The structure strength of the fluid solid thermal coupling of the valve mechanism is studied.The structure model of the valve plate is established.The corresponding boundary conditions are determined by the aerodynamic load and thermal load of the transient CFD simulation and the centrifugal load of the valve movement.The static analysis of the one-way fluid solid thermal coupling of the valve plate is carried out,and the main influence factors of the temperature variation characteristics and the strength of the valve plate are obtained factor;(4)Based on the Kriging model,the interpolation transfer of pressure and thermal load is completed,and the contact boundary conditions of the structure are determined.The valve mechanism is analyzed according to the multi field coupling theory,and the time-domain response and variation law of the fluid solid thermal coupling of the valve mechanism are obtained;(5)The multi field coupling dynamics of the rigid flexible coupling valve mechanism is analyzed,and the multi rigid body dynamics model of the valve mechanism is established.Based on the theoretical calculation of the motion characteristics,the correctness of the established model is verified by comparison.The key component valve plate is flexible,and the aerodynamic and thermal loads are introduced to analyze the motion law,structural strength and vibration response of the rigid flexible coupling valve mechanism Finally,some suggestions for structural optimization are put forward.