The paper examines the dynamic stall characteristics of a finite wing with an aspect ratio of eight in order to explore the 3D effects on flow topology,aerodynamic characteristics,and pitching damping.Firstly,CFD meth...The paper examines the dynamic stall characteristics of a finite wing with an aspect ratio of eight in order to explore the 3D effects on flow topology,aerodynamic characteristics,and pitching damping.Firstly,CFD methods are developed to calculate the aerodynamic characteristics of wings.The URANS equations are solved using a finite volume method,and the two-equation k-ωshear stress transport(SST)turbulence model is employed to account for viscosity effects.Secondly,the CFD methods are used to simulate the aerodynamic characteristics of both a static,rectangular wing and a pitching,tapered wing to verify their effectiveness and accuracy.The numerical results show good agreement with experimental data.Subsequently,the static and dynamic characteristics of the finite wing are computed and discussed.The results reveal significant 3D flow structures during both static and dynamic stalls,including wing tip vortices,arch vortices,Ω-type vortices,and ring vortices.These phenomena lead to differences in the aerodynamic characteristics of the finite wing compared with a 2D airfoil.Specifically,the finite wing has a smaller lift slope during attached-flow stages,higher stall angles,and more gradual stall behavior.Flow separation initially occurs in the middle spanwise section and gradually spreads to both ends.Regarding aerodynamic damping,the inboard sections mainly generate unstable loading.Furthermore,sections experiencing light stall have a higher tendency to produce negative damping compared with sections experiencing deep dynamic stall.展开更多
An effective method for delaying the dynamic stall of helicopter retreating blade by using the trailing edge flap has been established in this paper.The aerodynamic loads of blade section are calculated by using the L...An effective method for delaying the dynamic stall of helicopter retreating blade by using the trailing edge flap has been established in this paper.The aerodynamic loads of blade section are calculated by using the Leishman-Beddoes unsteady two-dimensional dynamic stall model and the aerodynamic loads of the trailing edge flap section are calculated by using the Hariharan-Leishman unsteady two-dimensional subsonic model.The analytical model for dynamic stall of elastic blade with the stiff trailing edge flap has been established.Adopting the aeroelastic analytical method and the Galerkin's method combined with numerical integration,the aeroelastic responses of rotor system in high-speed and high-load forward flight are solved.The mechanism for control of dynamic stall of retreating blade by using trailing edge flap has been presented.The numerical results indicate that the reasonably controlled swing of trailing edge flap can delay the dynamic stall of retreating blade under the same flight conditions.展开更多
基金supported by the National Natural Science Foundation of China(No.12072156)the National Key Laboratory Foundation of China(No.61422202103)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘The paper examines the dynamic stall characteristics of a finite wing with an aspect ratio of eight in order to explore the 3D effects on flow topology,aerodynamic characteristics,and pitching damping.Firstly,CFD methods are developed to calculate the aerodynamic characteristics of wings.The URANS equations are solved using a finite volume method,and the two-equation k-ωshear stress transport(SST)turbulence model is employed to account for viscosity effects.Secondly,the CFD methods are used to simulate the aerodynamic characteristics of both a static,rectangular wing and a pitching,tapered wing to verify their effectiveness and accuracy.The numerical results show good agreement with experimental data.Subsequently,the static and dynamic characteristics of the finite wing are computed and discussed.The results reveal significant 3D flow structures during both static and dynamic stalls,including wing tip vortices,arch vortices,Ω-type vortices,and ring vortices.These phenomena lead to differences in the aerodynamic characteristics of the finite wing compared with a 2D airfoil.Specifically,the finite wing has a smaller lift slope during attached-flow stages,higher stall angles,and more gradual stall behavior.Flow separation initially occurs in the middle spanwise section and gradually spreads to both ends.Regarding aerodynamic damping,the inboard sections mainly generate unstable loading.Furthermore,sections experiencing light stall have a higher tendency to produce negative damping compared with sections experiencing deep dynamic stall.
基金supported by the National Natural Science Foundation of China (Grant No. 5107520)the Fundamental Research Funds for the Central Universities (Grant No. NP2011057)
文摘An effective method for delaying the dynamic stall of helicopter retreating blade by using the trailing edge flap has been established in this paper.The aerodynamic loads of blade section are calculated by using the Leishman-Beddoes unsteady two-dimensional dynamic stall model and the aerodynamic loads of the trailing edge flap section are calculated by using the Hariharan-Leishman unsteady two-dimensional subsonic model.The analytical model for dynamic stall of elastic blade with the stiff trailing edge flap has been established.Adopting the aeroelastic analytical method and the Galerkin's method combined with numerical integration,the aeroelastic responses of rotor system in high-speed and high-load forward flight are solved.The mechanism for control of dynamic stall of retreating blade by using trailing edge flap has been presented.The numerical results indicate that the reasonably controlled swing of trailing edge flap can delay the dynamic stall of retreating blade under the same flight conditions.
