Link to video for part D 3. A wing tip vortex is formed due to air at high press

Question

Link to video for part D

3. A wing tip vortex is formed due to air at high pressure below the wing spilling over to the top of the wing near the tip (Fig. P3a). It creates a "downwash" (Fig. P3b). The downwash affects the angle at which wind is incident onto the wing from the front. The wind, instead of being horizontal, now has a downward component. [25 pts] Pressure Profile Swirling Air Tip Vortices" Drag High Pressure air Spilils Over Wing Into Low Pressure Above Wing Figure P3a Figure P3b a) Use the information above to explain how the wing tip vortex reduces lift. b) How would the pressure in the core of the vortex affect the drag on the wings?

Explanation / Answer

a) Wingtip vortex are produced when a wing generates lift. it is a pattern of rotating air which is trailing behind wings. they are the consequence of lift generation of wings. For a 3 dimensional wing an effect on lift called downwash occurs which affects the angle at which wind is incident on the wing. The downwash produced is very strong near the wing tips. The effective angle of attack is hence reduced and gives an downward component over the entire wing adn is called induced drag . The local flow is hence at lower angle than free stream flow. Resolution of the wing tp lift back to free stream reference produces reduction in lift coefficient of entire wing.

b) The vortex produced due to the wingtips are associated with the induced drag , downwash effect and are cause of lift generation. The air on the top surface of the has lower pressure than bottom surface when lift is generated. Air flows from higher to lower pressure.Near the wingtips air is free to move . Hence vortex is observed which has a circular pattern and also a low pressure core. the wingtip produces downwash and the downstream component of the force is called induced drag. Hence the drag is affected by the pressure in the core.

c) The function of winglets on the tails of the wings are to reduce turbulence at the tips of the airplane wing. Air pressure is higher on the bottom than that of the top. The air flows from higher pressure to lower and meets at the wingtips it forms a vortex. Winglets help reduce the force of the vortex by breaking it up and reduces drag which in turn saves fuel. They tend to increase performance, increase range and also decrease amount of fuel burn by opposing the drag created by wingtip vortices. Winglets create forward lift and they create it perpendicular to the relative wind. Blending of winglets reduce even more drag which eliminates interference drag and makes them more efficient.

d) The drag created at the wingtips for a GEV is reduced and vortex builds up below the wings and increases the lift of the GEV. This increase of lift and decrease of drag gives better performance for the GEV. The aerodynamic interaction between wings and the surface is used by GEV. The Airfoil Flairboats are example of GEV. They need some forward velocity to produce lift and lift dependent dragis produced with ground effect. The closer the wing operates to the ground the more effcient it becomes.

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