Research And Application Of Turbine Inverse Problem Based On Streamline Curvature Method

Axial flow turbine is one of the most important components of aeroengine and ground gas turbine.Its aerodynamic design directly determines the performance of the engine and gas turbine.The research on advanced aerodynamic design methods for turbines has always been the core content of turbine research.Although CFD numerical simulation technology now plays an important role in the full three-dimensional design system of turbines,as the basis of the full three-dimensional design system,turbine S2 flow surface design(two-dimensional throughflow)is still the main content of turbine aerodynamic design.In the throughflow design stage,the overall performance parameters and the profile parameters of each section of the turbine are roughly determined,thus completing most of the content of turbine design.In this paper,the inverse problem of throughflow design of axial flow turbines based on streamline curvature method is studied.The main work contents include the following aspects:Firstly,the governing equation of the inverse problem of streamline curvature method used in the throughflow design of S2 flow surface in turbine is derived,and the meridian velocity equation is solved discretely by using the knowledge of differential equations.Then,a throughflow inverse design program for multistage axial flow turbines is developed by using Fortran90 language,which is suitable for both ideal gas and real gas.The turbine inlet boundary conditions,meridional flow passage and blade circulation distribution information are given to design the turbine fastly.Then,the single-stage and multi-stage ideal gas turbines and an organic Rankine cycle expander using R245 fa as working medium were designed and calculated by using the program.By comparing with the CFD three-dimensional numerical simulation results,it is found that the overall turbine performance parameters calculated by the program and the aerodynamic parameters of each calculation station are in good agreement with the CFD results,which preliminarily verifies the effectiveness of the inverse design program.Finally,this paper combines the developed turbine inverse design program with Mode Frontier software to study the performance changes of a single-stage axial flow turbine under different circulation distribution laws,such as linear,parabolic,exponential,etc.,by using the optimization algorithm,so as to provide some guidance for the turbine inverse problem on how to set the circulation.The multistage axial flow turbine inverse design program developed in this paper is universal to a certain extent,but its accuracy needs to be further improved by improving the empirical model,so that it can be truly incorporated into the quasi-three-dimensional turbine design system.