The results show that increasing the level of free-stream turbulence intensity leads to a decrease in separation bubble length, attributed to a downstream shift in mean separation and an upstream shift in mean reattachment, the later ascribed to an upstream shift in mean transition. All experiments are performed for an angle of attack of 4°, chord Reynolds numbers of 80,000 and 125,000, and free-stream turbulence intensities between 0.06 and 1.99%. The laminar-to- turbulent transition process in a laminar separation bubble formed over a NACA 0018 airfoil is investigated experimentally. However, turbulence kinetic energy and eddy dissipation contours vary as turbulence intensity changes, but their changes are disproportionally small, compared with values adopted for free-stream turbulence.Įffects of free-stream turbulence intensity on transition in a laminar separation bubble formed over an airfoil Results revealed that drag and lift coefficients are approximately the same at every aforementioned value of turbulence intensity.
#DIETER DER FILM STREAMCLOUD FREE#
Numerical simulations were performed, with free stream turbulence intensity ranging from low (1%), medium (5%) to high (10%) levels. A Shear Stress Transport (SST) turbulence model is validated against experimental data available in the literature. Mesh refinement using a mesh-adaption technique based on velocity gradient is presented for more accurate prediction of shocks and boundary layers. The finite volume method in a commercial CFD package ANSYS-CFX is used to perform the numerical analysis of the flow. In particular, NACA 0012 airfoil performance at Ma∞ = 0.7 is considered in terms of drag, lift, turbulence kinetic energy, and turbulence eddy dissipation parameters under the influence of varying angle of attacks and free-stream turbulence. This paper presents the influence of free-stream turbulence intensity on transonic flow over an airfoil in the presence of a weak shock wave.
In transonic flow conditions, typically in the military or aerospace applications, existence of nonlinear and unsteady effects of the airflow stream significantly alters the performance of an airfoil. During these flight conditions the free-stream approaching the wings undergo fundamental changes. Zhao, Y.Īirplanes regularly operate switching between various flight modes such as take-off, climb, cruise, descend and landing. Effect of Free-Stream Turbulence Intensity on Transonic Airfoil with Shock Wave
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