Abstract
The performance of the airfoil is strongly dependent on the development of the boundary layer on the surface and therefore an accurate prediction of the laminar to turbulent transition onset is essential. A grid independence study is performed, turbulence variables values have been changed frequently, regularly, and carefully so that they cover the entire range of acceptable values reported by previous researches. Effects of turbulent variating at far stream on turbulent boundary layer structure and on transition stage characteristics at moderate Reynolds number have been studied over a full range of angles of attack of NACA0012. numerical results have been post-processed, analyzed and found that far stream turbulence variables have a significant effect on transition characteristic, their effects on skin friction is limited to small extent along wing surface where transition take place, increasing turbulence intensity or eddy viscosity ratio at far boundary shifts transition onset towards leading edge and increase transition length.
Highlights
Flows at moderate and high Reynolds number are characterized by complex turbulent boundarylayer effects, including leading-edge laminar-to-turbulent transition, flow reattachment, trailingedge separation, and leading-edge separation.Laminar-to-turbulent transition in shear layer of the flows over airfoil is of particular importance, it has subjected to intensive research over the past decades but it still far from completely understood.The location where transition starts, and the spatial extension occupied by it are of a great importance in the airfoil performance
Ning Cao focused in his study on the independent effects of the turbulence intensity and integral length scale on the and, of an asymmetric, high lift airfoil, at different R and found that increasing leads to delay stall at high angle of attack [13], a literature review shows that there is a little investigation about the effects of eddy viscosity ratio at certain value of turbulent intensity on the transition character over airfoil at moderate Reynold number
The Menter Shear Stress Transport Turbulence Model k-ω SST is a two-equation eddy-viscosity model used for many hydrodynamic and aerodynamic applications, this model combines the well-known low Reynolds turbulence model − and high Reynolds turbulence model −, the former is suitable for simulating flow in the viscous sub-layer but it suffers from a high sensitivity to the inlet free-stream turbulence properties, while the latter is ideal for predicting flow behavior in regions away from the wall but it performs poorly in adverse pressure gradient situations and cannot be used all the way down to wall
Summary
Flows at moderate and high Reynolds number are characterized by complex turbulent boundarylayer effects, including leading-edge laminar-to-turbulent transition, flow reattachment, trailingedge separation, and leading-edge separation. Ning Cao focused in his study on the independent effects of the turbulence intensity and integral length scale on the and , of an asymmetric, high lift airfoil, at different R and found that increasing leads to delay stall at high angle of attack [13], a literature review shows that there is a little investigation about the effects of eddy viscosity ratio at certain value of turbulent intensity on the transition character over airfoil at moderate Reynold number. Bridging this gap is the main motivation of current study. Труды ИСП РАН, том 31, вып. 6, 2019 г., стр. 203–214
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
