Document Type : Original Article


Department of Chemical Engineering, Calgary University, Canada


Fluid molecules adhere to objects due to their viscosity when passing through them, thus causing friction between the fluid and the body. This friction depends on the type of surface, its amount, fluid characteristics and flow. There is a transition zone between the stratified boundary cortex and the turbulent region. This practice has been extensively researched in airfoils, especially in Transonic airfoils. For example, research at NASA (ACEE: Air Craft Energy Efficiency) was conducted in the 1970s and 1980s. In this regard, they have succeeded in making airfoils with a border layer up to 60% on the upper edge and up to 50% layer on the lower edge, for the angle swept by the airfoil 26 degrees and Mach number 0.81-0.85 and Reynolds number Chord. The reduction rate of airfoil drag coefficient was 55% compared to the same airfoil with 26 angle and completely turbulent flow. As mentioned before, blowing can delay the onset of disturbance. The physical cause of this will be discussed in the section on secondary fluid. The blowing action can either give more momentum to the fluid and delay the separation, or it can dampen the turbulence and keep the boundary layer layered, thus delaying the transition point. NASA has re-used the airfoil of the previous topic and used blowing in it. The name of these airfoils (ATC: Anti Separtation Tailord Control) has been specified.


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