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
针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加...针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加权的前飞速度和横向速度对操纵量、姿态角、气动导数和操纵导数进行三维插值,对气动力进行实时计算,完成了UH-60直升机的LPV-MPC系统建模。采用粒子群优化算法,针对前飞速度插值间隔、横向速度插值间隔和滤波常数等三个建模参数进行优化。利用UH-60直升机非线性模型生成一系列用于优化的线性状态空间模型,对直升机纵向通道、横向通道同时给定激励进行仿真试验。仿真结果表明:在一定范围内任意选取的优化参数,经过粒子群寻优后,建立的LPV-MPV模型精度更高。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.
文摘针对直升机飞行动力学建模参数优化问题,提出了一种基于粒子群的线性变参数模型预测控制(Linear parameter variable and model predictive control,LPV-MPC)优化设计,通过优化建模参数,提高直升机飞行动力学建模精度。基于经过滤波加权的前飞速度和横向速度对操纵量、姿态角、气动导数和操纵导数进行三维插值,对气动力进行实时计算,完成了UH-60直升机的LPV-MPC系统建模。采用粒子群优化算法,针对前飞速度插值间隔、横向速度插值间隔和滤波常数等三个建模参数进行优化。利用UH-60直升机非线性模型生成一系列用于优化的线性状态空间模型,对直升机纵向通道、横向通道同时给定激励进行仿真试验。仿真结果表明:在一定范围内任意选取的优化参数,经过粒子群寻优后,建立的LPV-MPV模型精度更高。
