Chemical Engineering
Frank Rebout
Abstract
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 ...
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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.
Chemical Engineering
Frank Rebout
Abstract
There are many ways to reduce the coefficient of friction as a result of pressure drop in internal flows and thrust force in external flows. For example, film suction, injection of gas bubbles in the boundary layer, use of magnetic fluid, etc., which are mostly intermediate fluids. Polymers are among ...
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There are many ways to reduce the coefficient of friction as a result of pressure drop in internal flows and thrust force in external flows. For example, film suction, injection of gas bubbles in the boundary layer, use of magnetic fluid, etc., which are mostly intermediate fluids. Polymers are among the materials that can be used as intermediate fluids. Due to their ring structure and chain structure, polymer particles stretch and elongate when they are inside the stream. This stretching first absorbs energy from the fluid and does not allow this energy to be used to produce vortices. Second, stretching the polymer chain like a wall prevents the growth of vortices. The higher the molecular mass of the polymer, the greater the drop loss and the lower the critical concentration due to the heavier the polymer. As the concentration of polymer in water increases, the drop curve in terms of discharge towards the horizontal axis of Shifa and gets closer to it. In other words, the friction drops decreases. Percentage drop for 100gr per cubic meter of water is 4.54%, 200gr per cubic meter is 12.78%, 300gr per cubic meter is 27%, 400gr per cubic meter is 30.7% and 500gr per cubic meter is 39.4%, the maximum amount of reduction is.
