Numerical Simulation For Flow Field Of Helicopters Based On High-precision Scheme

Rotor is the main source of lift for helicopters.The aerodynamic characteristics of rotor have a significant impact on helicopter noise levels,vibration levels,flight performance,and flight quality.Therefore,it is very important for the development of helicopters to effectively simulate the rotor vortex flow field with high-precision numerical scheme to accurately predict the rotor aerodynamic characteristics.The first chapter mainly introduces the research background of this paper and the current status of domestic and foreign research in the related fields such as numerical simulation of rotor flow field,high-precision scheme and numerical simulation of helicopter interaction flow field.It indicates the significance of developing high-precision numerical simulation method of rotor flow field and studying helicopter aerodynamic interaction such as rotor/fuselage aerodynamic interaction,and gives the main research content of this paper.In the second chapter,based on the RANS equation,a set of high-precision rotor CFD method with low dissipation for cell-centered scheme is developed.The spatial discretization method for convective flux on the Cartesian background grid uses the seventh-order Roe-WENO scheme to reduce the numerical dissipation during the blade tip vortex transport,and the spatial discretization method for convective flux on the unstructured body-fitted grid uses Roe-piecewise linear scheme;the time discretization method uses the dual time implicit LU-SGS method for time advancement.The third chapter mainly introduces the unstructured overset grid technology of cell-centered scheme,and introduces related technologies such as searching the host cell,calculation of distance to the wall and numerical transmission between nested grids.In the fourth chapter,the high-precision rotor CFD method established above is used to calculate the vortex flow field of rotors in different shapes in hover,and we compare the calculation results with the experimental data,which verifies the effectiveness of the method to numerically simulate the rotor flow field.At the same time,we compare the rotor blade tip vortex capture effect with the results of JST scheme,which reflects the lower numerical dissipation of the high-precision rotor CFD method in this paper.Then,the high-precision rotor CFD method established above is applied to calculate the helicopter rotor/fuselage aerodynamic interaction flow field.And the calculation results were compared with experimental data,which verifies the effectiveness of the high-precision CFD method to calculate the helicopter rotor/fuselage interaction flow field.In the fifth chapter,the high-precision rotor CFD method established above is further extended to calculate the double-thrust-propeller configuration compound high-speed helicopter aircraft flow field,and the in-depth calculation and analysis of the interaction characteristics of this configuration compound high-speed aircraft flow field are performed.Then,the flow fields of different combined models are compared to obtain some conclusions about aircraft interaction characteristics of the compound high-speed helicopter flow field,which provides a reference for the design of this configuration of helicopter in the future.