In view of the reduction of hovering efficiency near high tension when a helicopter rotor hovers,a numerical simulation method of lifting rotor hovering aerodynamic characteristics based on leading edge droop is estab...In view of the reduction of hovering efficiency near high tension when a helicopter rotor hovers,a numerical simulation method of lifting rotor hovering aerodynamic characteristics based on leading edge droop is established in this paper. It is dominated by Reynolds average N-S equation in integral form. Firstly,VR-12 airfoil is taken as the research object,and the influence of leading edge droop angle on the aerodynamic characteristics of two-dimensional airfoil is studied. Secondly,the modified 7 A rotor is taken as the research object,and the effects of different leading edge droop angles at the position of blade r/R=0.75—1 on the aerodynamic characteristics in hover are explored. It is found that the leading edge droop can significantly improve the aerodynamic characteristics of two-dimensional airfoil and three-dimensional hovering rotor near high angle of attack,and can effectively inhibit the generation of stall vortex.展开更多
Rotor wake analysis,a fundamental research of helicopter technology,has been widely applied for rotor aerodynamic analysis. This paper summarizes the research of different rotor wake models at home and abroad and revi...Rotor wake analysis,a fundamental research of helicopter technology,has been widely applied for rotor aerodynamic analysis. This paper summarizes the research of different rotor wake models at home and abroad and reviews the development process of rotor wake methods as well as the research achievement obtained in each stage.Then,the new progress of helicopter rotor wake methods is described in detail. It includes constant circulation contours modeling method of rotor wake,pseudo-implicit relaxation iteration and time-accurate solution method,research on aerodynamic interaction characteristics of helicopter rotor/fuselage by wake method,research on the rotor blade-vortex interaction noise and interaction of coaxial rigid rotor aerodynamics by viscous vortex particle method,and application of free wake method to helicopter flight dynamics modeling. In the end,some prospects for the research of helicopter rotor wake method are put forward,which clarifies the ideas for the future development of rotor wake method.展开更多
Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m ? 6 m low-speed straightflow wind tunnel of China Aerod...Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m ? 6 m low-speed straightflow wind tunnel of China Aerodynamics Research and Development Center. In the experiment,a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and firstorder flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root.Rotor aerodynamic performance is measured under hovering and high advance ratio conditions.Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases.展开更多
The discontinuous Galerkin(DG) method is established and innovatively conducted on accurately simulating the evolution of blade-tip vortex and the aerodynamic characteristics of helicopter rotor. Firstly,the Reynolds-...The discontinuous Galerkin(DG) method is established and innovatively conducted on accurately simulating the evolution of blade-tip vortex and the aerodynamic characteristics of helicopter rotor. Firstly,the Reynolds-Averaged Navier-Stokes(RANS)equations in rotating reference frame are employed,and the embedded grid system is developed with the finite volume method(FVM)and the DG method conducted on the blade grid and background grid respectively. Besides,the Harten-Lax-Van Leer contact(HLLC)scheme with high-resolution and low-dissipation is employed for spatial discretization,and the explicit third-order Runge-Kutta scheme is used to accomplish the temporal discretization. Secondly,the aerodynamic characteristics and the evolution of blade-tip vortex for Caradonna-Tung rotor are simulated by the established CFD method,and the numerical results are in good agreement with experimental data,which well validates the accuracy of the DG method and shows the advantages of DG method on capturing the detailed blade-tip vortex compared with the FVM method. Finally,the evolution of tip vortex at different blade tip Mach numbers and collective pitches is discussed.展开更多
基金supported by the National Natural Science Foundation of China(No.11972190)the Aeronautical Science Foundation of China(No. 20185752)
文摘In view of the reduction of hovering efficiency near high tension when a helicopter rotor hovers,a numerical simulation method of lifting rotor hovering aerodynamic characteristics based on leading edge droop is established in this paper. It is dominated by Reynolds average N-S equation in integral form. Firstly,VR-12 airfoil is taken as the research object,and the influence of leading edge droop angle on the aerodynamic characteristics of two-dimensional airfoil is studied. Secondly,the modified 7 A rotor is taken as the research object,and the effects of different leading edge droop angles at the position of blade r/R=0.75—1 on the aerodynamic characteristics in hover are explored. It is found that the leading edge droop can significantly improve the aerodynamic characteristics of two-dimensional airfoil and three-dimensional hovering rotor near high angle of attack,and can effectively inhibit the generation of stall vortex.
文摘Rotor wake analysis,a fundamental research of helicopter technology,has been widely applied for rotor aerodynamic analysis. This paper summarizes the research of different rotor wake models at home and abroad and reviews the development process of rotor wake methods as well as the research achievement obtained in each stage.Then,the new progress of helicopter rotor wake methods is described in detail. It includes constant circulation contours modeling method of rotor wake,pseudo-implicit relaxation iteration and time-accurate solution method,research on aerodynamic interaction characteristics of helicopter rotor/fuselage by wake method,research on the rotor blade-vortex interaction noise and interaction of coaxial rigid rotor aerodynamics by viscous vortex particle method,and application of free wake method to helicopter flight dynamics modeling. In the end,some prospects for the research of helicopter rotor wake method are put forward,which clarifies the ideas for the future development of rotor wake method.
文摘Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m ? 6 m low-speed straightflow wind tunnel of China Aerodynamics Research and Development Center. In the experiment,a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and firstorder flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root.Rotor aerodynamic performance is measured under hovering and high advance ratio conditions.Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases.
基金supported by the National Natural Science Foundation of China(Nos.12072156, 12032012)the Foundation of Rotor Aerodynamic Key Laboratory (No.RAL20190102)the Priority Academic Program Development Project of Jiangsu Higher Education Institutions(PAPD)。
文摘The discontinuous Galerkin(DG) method is established and innovatively conducted on accurately simulating the evolution of blade-tip vortex and the aerodynamic characteristics of helicopter rotor. Firstly,the Reynolds-Averaged Navier-Stokes(RANS)equations in rotating reference frame are employed,and the embedded grid system is developed with the finite volume method(FVM)and the DG method conducted on the blade grid and background grid respectively. Besides,the Harten-Lax-Van Leer contact(HLLC)scheme with high-resolution and low-dissipation is employed for spatial discretization,and the explicit third-order Runge-Kutta scheme is used to accomplish the temporal discretization. Secondly,the aerodynamic characteristics and the evolution of blade-tip vortex for Caradonna-Tung rotor are simulated by the established CFD method,and the numerical results are in good agreement with experimental data,which well validates the accuracy of the DG method and shows the advantages of DG method on capturing the detailed blade-tip vortex compared with the FVM method. Finally,the evolution of tip vortex at different blade tip Mach numbers and collective pitches is discussed.
