An Investigation On Numerical Simulation Method For The Internal Flow In The Single Channel Of Axial Compressor

In the current design system of the aeroengine,the design of the compressor/fan has gradually developed into the three dimensional stage.As a result,the numerical simulation of three dimensional flow field around the compressor based on the Navier-Stokes equation has become crucial to the design and analysis of compressor.In the initial design stage,the geometry of the compressor is updated and the flow field around which is simulated during every iteration.A fast numerical simulation of the flow field with acceptable accuracy is desired.In order to obtain an excellent design,it is necessary to conduct the numerical simulation of the flow around the compressor designed with high accuracy to decrease the risk of experiment.Thus,choosing a numerical simulation method whose accuracy is as high as possible on condition that the computational cost and computational efficiency are acceptable is of importance.To do research on the applicability and features of different numerical simulation methods,and to explore the internal flow features of the compressor,the numerical methods which solve the single channel flow field of compressor including the mixing plane method,the harmonic balance method and the phase lag method together with the unsteady simulation method(URANS methods)which solves the multi channels flow field of compressor are developed based on the CFD solver program developed by the research team I belong to.Through comparing the simulation results of single channel algorithms with the results of experiment and the simulation results of commerical software,it is validated that the single algorithms developed can be applied to the numerical simulation of flow field in turbomachinery.In the numerical examples provided by the thesis,it is validated that the harmonic balance method and the phase lag method can simulate the unsteady flow with the same accuracy of the URANS method,with the computational efficiency one order of magnitude higher than the URANS method.In the first chapter,the background and significance of the research is introduced,following which is the development history and the current situation of the research in CFD of the compressor,the main content of the thesis is introduced at last.In the second chapter,the numerical method is introduced,including the governing equations of the flow around the compressor,the numerical schemes,the turbulence models and boundary conditions.In the third chapter,research is conducted on a single stage compressor.Firstly the feature curves in the design speed are calculated by the single channel algorithms,which are compared with the results of experiment and the simulation results of commerical software.The results of comparisons indicate that the single channel algorithms and programs developed are effective in the simulation of turbomachinery.Under the same boundary conditions,the simulation results of single channel algorithms are compared with those of URANS method,which include flow field details,global parameters and spectral analysis.All the results are nearly the same,validating that the unsteady flow fields simulated by the harmonic balance method and the phase lag method are correct.Finally,it is validated that the single channel algorithms are also suitable for the simulation of the flow around the rotating cascades.In the fourth chapter,the flow around multi stage compressor with single fundamental frequency is studied.It is validated that the harmonic balance method and the phase lag method which are suitable for the simulation of flow around the single stage compressor can be extended to the simulation of flow around the multi stage compressor without any change in the program and algorithms.The fifth chapter focuses on the simulation of flow around the mult i stage compressor with multi fundamental frequencies.Firstly,the robustness of the harmonic balance method on the simulation of flow with more than one fundamental frequencies is guaranteed by coupling the CFD algorithm with the optimization algorithm.Then the algorithm of the phase lag method is extended to the simulation of flow with multi fundamental frequencies.Finally the result of single channel algorithms and URANS mehod are compared and analysed.In the sixth chapter,the content of this thesis is summarized,the shortcomings are also pointed out,following which is the expectation for the future work.