Pumping Air Over Wing: Advantages & Disadvantages?

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In summary, pumping air over a wing can have both advantages and disadvantages depending on the angle of attack and uniformity of the airflow. It can help reduce turbulence and increase lift, but it can also detach the boundary layer and cause uneven lift distribution. Blowing air under the wing may result in increased performance, but it may also require complex ducting and decrease space for fuel tanks. Winglets are oriented with a positive angle to help reduce drag, and having both positive and negative winglets may improve performance in small aircraft. However, implementing this suggestion may require significant research and development. Additionally, research has been done on sucking air through a porous wing wall to delay boundary layer detachment and decrease drag.
  • #1
sid_galt
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pumping air over wing??

So if hot/cold air is blown over the top surface of a small sized wing inflight which has a medium angle of attack, will it help in the lift or will it be a disadvantage?

I can only think of two things

1) Advantage: It will reenergize the airflow and help in reducing turbulence. Higher speed of wind will decrease pressure and increase lift though temperature of hot air might render the effects of the increased lift negligible.

2) Disadvantage: It might detach the boundary layer and might increase the drag substantially. If the blow speed gets even a little bit uneven, it may destabalize the aircraft considerably. It will result in uneven distribution of lift across the wingspan unless the air is uniformly blown all over the wing. This will result in increased stress.

What do you think?

If it turns out to be a disadvantage, would blowing the air under the wing instead of the top result in increased performance/lift?


Also a question about winglets. Why are winglets oriented with a positive angle and not a negative one? What if one has two winglets with + and - angles? Would that help in performance especially in small aircraft?
 
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  • #2
The suggestion is not new. However the problem with pumping air through pores in the wing is that large amounts of complex ducting and pumps will be required. Space in the wing normally reserved for fuel tanks will also need to be cut down.
 
  • #3
Speed said:
The suggestion is not new. However the problem with pumping air through pores in the wing is that large amounts of complex ducting and pumps will be required. Space in the wing normally reserved for fuel tanks will also need to be cut down.

Ducting, energy issues and pumps aside, will the suggestion actually work with either hot or cold air even on low Reynold number wings?
 
  • #4
sid_galt said:
Ducting, energy issues and pumps aside, will the suggestion actually work with either hot or cold air even on low Reynold number wings?

I don't see any advantage, besides I don't understand the advantages you posted. Pumping air will increase turbulence instabilities and drag.

The fact is it has been a lot of research in sucking air through a porous wing wall. The suction of air delays the boundary layer point of detachtment, decreasing drag.

Some turbomachine blades are machined in such a way to have such porous wall.
 
  • #5
I was going to mention boundary layer control experiments using vacuums but Clausius beat me to it.

You may want to look at this link:
http://aerodyn.org/Drag/blc.html

It does talk about injection techniques.
 
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1. What is the purpose of pumping air over a wing?

The main purpose of pumping air over a wing is to increase the lift and reduce the drag of an aircraft. This is achieved by creating a higher pressure above the wing and a lower pressure below the wing, which results in an upward force.

2. How does pumping air over a wing improve aircraft performance?

Pumping air over a wing can improve aircraft performance in several ways. Firstly, it increases the lift, allowing the plane to fly at a lower speed and take off and land at shorter distances. It also reduces drag, which improves fuel efficiency and allows for higher speeds. Additionally, pumping air over a wing can improve the stability and control of the aircraft.

3. What are the advantages of using a pumped wing design?

The advantages of using a pumped wing design include increased lift, reduced drag, improved fuel efficiency, and better stability and control. This can result in improved performance, shorter takeoff and landing distances, and the ability to carry heavier loads.

4. Are there any disadvantages to pumping air over a wing?

One potential disadvantage of pumping air over a wing is the added complexity and weight of the necessary equipment. This can increase the cost and maintenance requirements of the aircraft. Additionally, in certain weather conditions, such as high winds or turbulence, the pumped wing design may not be as effective.

5. How is air pumped over a wing?

Air is typically pumped over a wing using a system of slots, ducts, and vents that allow air to flow over the top of the wing. This can be achieved through various methods, such as using engine bleed air or electric fans. The amount of air pumped over the wing can also be controlled to adjust the lift and drag as needed.

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