High-speed rotor rotation under the low-density condition creates a special low-Reynolds compressible flow around the rotor blade airfoil where the compressibility effect on the laminar separated shear layer occurs. H...High-speed rotor rotation under the low-density condition creates a special low-Reynolds compressible flow around the rotor blade airfoil where the compressibility effect on the laminar separated shear layer occurs. However, the compressibility effect and shock wave generation associated with the increase in the Mach number (M) and the trend change due to their interference have not been clarified. The purpose is to clear the compressibility effect and its impact of shock wave generation on the flow field and aerodynamics. Therefore, we perform a two-dimensional unsteady calculation by Computational fluid dynamics (CFD) analysis using the CLF5605 airfoil used in the Mars helicopter Ingenuity, which succeeded in its first flight on Mars. The calculation conditions are set to the Reynolds number (Re) at 75% rotor span in hovering (Re = 15,400), and the Mach number was varied from incompressible (M = 0.2) to transonic (M = 1.2). The compressible fluid dynamics solver FaSTAR developed by the Japan aerospace exploration agency (JAXA) is used, and calculations are performed under multiple conditions in which the Mach number and angle of attack (α) are swept. The results show that a flow field is similar to that in the Earth’s atmosphere above M = 1.0, such as bow shock at the leading edge, whereas multiple λ-type shock waves are observed over the separated shear layer above α = 3° at M = 0.80. However, no significant difference is found in the C<sub>p</sub> distribution around the airfoil between M = 0.6 and M = 0.8. From the results, it is found that multiple λ-type shock waves have no significant effect on the airfoil surface pressure distribution, the separated shear layer effect is dominant in the surface pressure change and aerodynamic characteristics.展开更多
Icing on blade surface of the straight-bladed vertical axis wind turbine(SB-VAWT)set in cold regions is a serious problem.To study the performance effects of icing on SB-VAWT,numerical simulations were carried out on ...Icing on blade surface of the straight-bladed vertical axis wind turbine(SB-VAWT)set in cold regions is a serious problem.To study the performance effects of icing on SB-VAWT,numerical simulations were carried out on the ice accretion on NACA 0015 airfoil which was always used for blade airfoil of SB-VAWT by CFD methods based on 2D steady incompressible N-S Equation.The morphology and procedure of icing on blade airfoil were obtained under different wind speeds,attack angles of blade and water flow flux in wind.The static flow fields,especially the static pressure fields around blade airfoil with or without icing on it were computed.The aerodynamic characteristics including the lift and drag force coefficients of blade airfoil were also calculated.The results indicated that icing caused the static pressure field changed greatly and led to the increasing of drag force and reducing the aerodynamic performance.展开更多
According to the construction principle of B-spline, a formula of surface construction for airfoil blade with the given points has been derived. Meanwhile, the surface construction system for airfoil blade in practice...According to the construction principle of B-spline, a formula of surface construction for airfoil blade with the given points has been derived. Meanwhile, the surface construction system for airfoil blade in practice as well as menus for the system have been constructed with the help of the commercial software (AutoCAD R14). The result in this paper is helpful for CAD/CAM of airfoil blades.展开更多
文摘High-speed rotor rotation under the low-density condition creates a special low-Reynolds compressible flow around the rotor blade airfoil where the compressibility effect on the laminar separated shear layer occurs. However, the compressibility effect and shock wave generation associated with the increase in the Mach number (M) and the trend change due to their interference have not been clarified. The purpose is to clear the compressibility effect and its impact of shock wave generation on the flow field and aerodynamics. Therefore, we perform a two-dimensional unsteady calculation by Computational fluid dynamics (CFD) analysis using the CLF5605 airfoil used in the Mars helicopter Ingenuity, which succeeded in its first flight on Mars. The calculation conditions are set to the Reynolds number (Re) at 75% rotor span in hovering (Re = 15,400), and the Mach number was varied from incompressible (M = 0.2) to transonic (M = 1.2). The compressible fluid dynamics solver FaSTAR developed by the Japan aerospace exploration agency (JAXA) is used, and calculations are performed under multiple conditions in which the Mach number and angle of attack (α) are swept. The results show that a flow field is similar to that in the Earth’s atmosphere above M = 1.0, such as bow shock at the leading edge, whereas multiple λ-type shock waves are observed over the separated shear layer above α = 3° at M = 0.80. However, no significant difference is found in the C<sub>p</sub> distribution around the airfoil between M = 0.6 and M = 0.8. From the results, it is found that multiple λ-type shock waves have no significant effect on the airfoil surface pressure distribution, the separated shear layer effect is dominant in the surface pressure change and aerodynamic characteristics.
基金This study was sponsored by Scientific Research Fund of Heilongjiang Provincial Education Department(No.:1153h01)National Natural Science Foundation of China(No.:10702015)+1 种基金Natural Science Foundation of Heilongjiang Province of China(LC2009C36)supported by Northeast Agricultural University Scientific Research foundation started from 2008.
文摘Icing on blade surface of the straight-bladed vertical axis wind turbine(SB-VAWT)set in cold regions is a serious problem.To study the performance effects of icing on SB-VAWT,numerical simulations were carried out on the ice accretion on NACA 0015 airfoil which was always used for blade airfoil of SB-VAWT by CFD methods based on 2D steady incompressible N-S Equation.The morphology and procedure of icing on blade airfoil were obtained under different wind speeds,attack angles of blade and water flow flux in wind.The static flow fields,especially the static pressure fields around blade airfoil with or without icing on it were computed.The aerodynamic characteristics including the lift and drag force coefficients of blade airfoil were also calculated.The results indicated that icing caused the static pressure field changed greatly and led to the increasing of drag force and reducing the aerodynamic performance.
文摘According to the construction principle of B-spline, a formula of surface construction for airfoil blade with the given points has been derived. Meanwhile, the surface construction system for airfoil blade in practice as well as menus for the system have been constructed with the help of the commercial software (AutoCAD R14). The result in this paper is helpful for CAD/CAM of airfoil blades.
