We have investigated transition characteristics of a boundary layer on a NACA0012 airfoil with upstream wake generated by an airfoil aligned in tandem with zero angle of attack by measuring velocity signal using hot wire anemometer. Reynolds number based on airfoil chord varies from 2.0 x 105 to 6.0 x 105; distance between two airfoils varies from 0.037 to 1.0 of the chord length. To measure skin friction which is used to identify the transition onset and completion, we have devised a modified wall law to accommodate transitional flows with pressure gradient and nonuniform inflows. Variations of the skin friction are quite similar to that of the fiat plate boundary layer with turbulent inflow. It is found that measured velocity profiles are well consistent with ones computed by modified wall laws in the range up to y+ = 40. Turbulence of the upstream wake shifts the onset of transition upstream and the transitional region longer as the airfoils approach and the Reynolds number increases. Mean velocity distribution gradually varies from a laminar to the logarithmic one during the transition. We have found that the maximum rms velocity fluctuation is located over y+ = 15-20. Strong positive skewness of velocity fluctuation is observed at the onset of transition and the overall rms level of velocity fluctuation reaches 3.0-3.5 in the wall unit. The data are expected to develop a turbulence model for the simulation of transitional flow.
Flow characteristics of transitional boundary layer on the NACA0012 airfoil in wakes
1998
Seiten
Aufsatz (Konferenz)
Englisch
Numerical Investigation of Transitional Flows over a NACA0012 Airfoil
SAE Technical Papers | 2008
|Optimal Operation of the NACA0012-IK30 Airfoil
TIBKAT | 2023
|Optimal Operation of the NACA0012-IK30 Airfoil
AIAA | 2023
|