In this work,the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry (PIV) system.The experiment was carried out in a low speed wind tunnel ...In this work,the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry (PIV) system.The experiment was carried out in a low speed wind tunnel with a test section of 0.5 m × 0.5 m.The Reynolds number (Re),defined by the chord length of the wing (C),was 8.1×10 4.The angle of attack was fixed at 10°.The PIV measurements were made from 0 to 2C,measured from the trailing edge of the model.The dihedral angle of three flaps was 15°,0° and 15°,respectively.Compared with the clean airfoil,the one with three flaps significantly changed the wing tip vortex structure,the vorticity and the core of the wing tip vortex.The occurrence of three flaps decreased the gradient of pressure on the two sides of the wing tip,which depressed wing tip vortex formation to some extent.Vortices shed from three flaps influence the evolution of the wingtip vortex generated by the base airfoil.The interaction of those vortices resulted in a weakening of the wing tip vortex.展开更多
In the present study, the formation of the wing-tip vortex from a rectangular NACA0015 wing with a square tip at the Reynolds number of 1.8× 105 and the angles of attack （AOA） α = 8° and 10° were sim...In the present study, the formation of the wing-tip vortex from a rectangular NACA0015 wing with a square tip at the Reynolds number of 1.8× 105 and the angles of attack （AOA） α = 8° and 10° were simulated with an incompressible detached eddy simulation （DES） method and the Reynolds averaged Navier-Stokes （RANS） equations with the SA model respectively. Numerical results were compared with experimental results to validate the capability of the employed methods in resolving tip vortex flows. The results show that DES model could capture the complicated three-dimensional structures in the vortex, and the streamwise vorticity and the cross-flow velocity agree with the experiment results quite well, but RANS-SA model with the same grid as that of DES failed to capture the correct structures and under-predicted the streamwise vorticity in the vortex by 40%. The present study suggests that under the same calculation cost, DES but not RANS-SA could be used to effectively predict the flow characteristics in tip vortex.展开更多
基金supported by the National Natural Science Foundation of China(Grant No. 10642002)
文摘In this work,the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry (PIV) system.The experiment was carried out in a low speed wind tunnel with a test section of 0.5 m × 0.5 m.The Reynolds number (Re),defined by the chord length of the wing (C),was 8.1×10 4.The angle of attack was fixed at 10°.The PIV measurements were made from 0 to 2C,measured from the trailing edge of the model.The dihedral angle of three flaps was 15°,0° and 15°,respectively.Compared with the clean airfoil,the one with three flaps significantly changed the wing tip vortex structure,the vorticity and the core of the wing tip vortex.The occurrence of three flaps decreased the gradient of pressure on the two sides of the wing tip,which depressed wing tip vortex formation to some extent.Vortices shed from three flaps influence the evolution of the wingtip vortex generated by the base airfoil.The interaction of those vortices resulted in a weakening of the wing tip vortex.
基金supported by the National Natural Science Foundation of China(Grant No.11102110)
文摘In the present study, the formation of the wing-tip vortex from a rectangular NACA0015 wing with a square tip at the Reynolds number of 1.8× 105 and the angles of attack （AOA） α = 8° and 10° were simulated with an incompressible detached eddy simulation （DES） method and the Reynolds averaged Navier-Stokes （RANS） equations with the SA model respectively. Numerical results were compared with experimental results to validate the capability of the employed methods in resolving tip vortex flows. The results show that DES model could capture the complicated three-dimensional structures in the vortex, and the streamwise vorticity and the cross-flow velocity agree with the experiment results quite well, but RANS-SA model with the same grid as that of DES failed to capture the correct structures and under-predicted the streamwise vorticity in the vortex by 40%. The present study suggests that under the same calculation cost, DES but not RANS-SA could be used to effectively predict the flow characteristics in tip vortex.
