Research On One-dimensional Optimization Design Method For Positive And Negative Aerodynamic Problems Of Turbines Based On Thermal-Fluid-Structure Coupling

In turbine multidisciplinary multi-dimensional optimization design system,low-dimensional rapid optimization design plays a crucial role.Its combining with multi-objective optimization algorithm can speed up the selection of design parameters and predict turbine performance,which has been widely used in turbine optimization design process.However,the turbine characteristics calculation methods considering thermal-fluid-solid coupling are mainly concentrated on the three-dimensional field.In order to improve the calculation efficiency and speed up the design process,this paper studies a one-dimensional optimization design method for axial flow turbines considering thermal-fluid-solid coupling.Firstly,the development status of turbine optimization design is introduced,and the research advances of axial flow turbine loss model is summarized.For three-dimensional thermal-fluid-solid optimized design calculation of the disadvantage of slow,the one dimensional characteristics prediction based on thermal-fluid-solid coupling was organically combined multi-objective optimization algorithm;a turbine pneumatic multi-objective optimization design method of one dimensional axial flow turbine was established and one-dimensional aerodynamic optimization design of axial flow turbine was carried out.Secondly,the influence of thermal-fluid-solid coupling on turbine components was studied.A tip clearance calculation code was programmed in this paper in order to predict the variation of turbine tip clearance.On the premise of considering aerodynamic,centrifugal and thermal loads,the calculation model of turbine disc,casing and blade was established to predict tip clearance change.The stress distribution of each turbine component and tip clearance numerical calculation was carried out by means of ANSYS Workbench computational simulation platform.Then,on the basis of describing the calculation method of one-dimensional characteristics,the loss model and lag angle model are modified through the CFD calculation results,and the calculation program of one-dimensional characteristics of multistage turbines is developed.A characteristic line of a certain speed is calculated through the increase of turbine inlet flow rate.On the premise of given turbine inlet total temperature,total pressure,speed and physical properties of working medium,the variation relationship of turbine total-total efficiency and total-total expansion ratio with inlet flow rate is calculated.The results of the program was compared with the reference data,and the results show that the program has high accuracy in the prediction of axial flow turbine characteristics.Besides,the rare working medium turbine loss model has been explored and compared with the air turbine loss model.The numerical simulation results have been modified,and the accuracy of the modified helium-xenon turbine characteristics calculation results was found significantly improved.Finally,the multi-objective optimization method was organically combined with the one-dimensional inverse problem design method for axial turbines,the one-dimensional prediction method of tip clearance variation and the one-dimensional characteristic prediction method,and a one-dimensional optimization design method of axial turbines based on thermal-fluid-structure coupling was established.A one-dimensional optimization design was carried out by taking a single stage axial flow turbine as the prototype and the total to total expansion ratio and total to total efficiency of the optimized turbine were increased by 0.55%and 0.89% respectively.