Wind power harnesses the energy of galloping

[crazynutsx]

 

THE thought of wind power brings visions of giant turbines, high-altitude kites and graceful sailboats to mind. But the breeze has a more sinister side, full of turbulence that can wreak havoc with bridges and other structures.

 

Now Hyung-Jo Jung and Seung-Woo Lee at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, plan to harness these destructive forces to generate energy. They have built a prototype that produces energy using a specific type of unstable airflow called wake galloping.

 

Wake galloping is a form of vigorous vibration that affects cylindrical parts of structures, such as the cables on suspension bridges, exposed to seemingly harmless airflow. When the wind passes a horizontal cylinder, eddy currents called wake vortices are created on the lee side. These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first.

 

The leeward cylinder's weight counteracts the lift by pulling it back down again, resulting in the cylinder repeatedly moving up and down as the wind continues to blow. It is this movement that Jung and Lee hope to harness as energy.

 

 

[swansont]

!

Moderator Note

Plagiarism is a big no-no, as is copyright violation.

http://www.newscientist.com/article/mg21028145.700-wind-power-harnesses-the-energy-of-galloping.html

[StringJunky]

You should have wrapped your post in quote tags with the link:

 

THE thought of wind power brings visions of giant turbines, high-altitude kites and graceful sailboats to mind. But the breeze has a more sinister side, full of turbulence that can wreak havoc with bridges and other structures.

 

Now Hyung-Jo Jung and Seung-Woo Lee at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, plan to harness these destructive forces to generate energy. They have built a prototype that produces energy using a specific type of unstable airflow called wake galloping.

 

Wake galloping is a form of vigorous vibration that affects cylindrical parts of structures, such as the cables on suspension bridges, exposed to seemingly harmless airflow. When the wind passes a horizontal cylinder, eddy currents called wake vortices are created on the lee side. These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first.

 

The leeward cylinder's weight counteracts the lift by pulling it back down again, resulting in the cylinder repeatedly moving up and down as the wind continues to blow. It is this movement that Jung and Lee hope to harness as energy. http://www.newscientist.com/article/mg21028145.700-wind-power-harnesses-the-energy-of-galloping.html

 

or italicise the post with the link attached:

 

THE thought of wind power brings visions of giant turbines, high-altitude kites and graceful sailboats to mind. But the breeze has a more sinister side, full of turbulence that can wreak havoc with bridges and other structures.

 

Now Hyung-Jo Jung and Seung-Woo Lee at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, plan to harness these destructive forces to generate energy. They have built a prototype that produces energy using a specific type of unstable airflow called wake galloping.

 

Wake galloping is a form of vigorous vibration that affects cylindrical parts of structures, such as the cables on suspension bridges, exposed to seemingly harmless airflow. When the wind passes a horizontal cylinder, eddy currents called wake vortices are created on the lee side. These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first.

 

The leeward cylinder's weight counteracts the lift by pulling it back down again, resulting in the cylinder repeatedly moving up and down as the wind continues to blow. It is this movement that Jung and Lee hope to harness as energy. http://www.newscientist.com/article/mg21028145.700-wind-power-harnesses-the-energy-of-galloping.html

 

or even just quotation marks at each end with the link to make it clear it's not your work...then you will avoid accusations of plagiarism.

 

As far as I know only partly quoting an article is permissible which is ok with your post here.

Edited June 10, 2011 by StringJunky

[J.C.MacSwell]

 

THE thought of wind power brings visions of giant turbines, high-altitude kites and graceful sailboats to mind. But the breeze has a more sinister side, full of turbulence that can wreak havoc with bridges and other structures.

 

Now Hyung-Jo Jung and Seung-Woo Lee at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, plan to harness these destructive forces to generate energy. They have built a prototype that produces energy using a specific type of unstable airflow called wake galloping.

 

Wake galloping is a form of vigorous vibration that affects cylindrical parts of structures, such as the cables on suspension bridges, exposed to seemingly harmless airflow. When the wind passes a horizontal cylinder, eddy currents called wake vortices are created on the lee side. These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first.

 

The leeward cylinder's weight counteracts the lift by pulling it back down again, resulting in the cylinder repeatedly moving up and down as the wind continues to blow. It is this movement that Jung and Lee hope to harness as energy.

 

This is clearly wrong (unless I have the context wrong) . Any cable diameter (at the right windspeed) will shed vortexes in oscillatory fashion giving rise to lift in one direction, at right angles to the cable and flow, and then the other.

[Ophiolite]

This is clearly wrong (unless I have the context wrong) . Any cable diameter (at the right windspeed) will shed vortexes in oscillatory fashion giving rise to lift in one direction, at right angles to the cable and flow, and then the other.

The authors are not harnessing energy from vortex shedding but, as noted in the extract, from wake galloping. Given that they have generated energy in wind tunnel tests the technique appears to be valid both theoretically and practically.

 

Hyung-JoJung, Seung-WooLee "The experimental validation of a new energy harvesting system based on the wake galloping phenomenon." Smart Mater. Struct. 20 (2011)

 

Abstract

In this paper, a new energy harvesting system based on wind energy is investigated. To this end, the characteristics and mechanisms of various aerodynamic instability phenomena are first examined and the most appropriate one (i.e. wake galloping) is selected. Then, a wind tunnel test is carried out in order to understand the occurrence conditions of the wake galloping phenomenon more clearly. Based on the test results, a prototype electromagnetic energy harvesting device is designed and manufactured. The effectiveness of the proposed energy harvesting system is extensively examined via a series of wind tunnel tests with the prototype device. Test results show that electricity of about 370 mW can be generated under a wind speed of 4.5 m s − 1 by the proposed energy harvesting device. The generated power can easily be increased by simply increasing the number of electromagnetic parts in a vibrating structure. Also, the possibility of civil engineering applications is discussed. It is concluded from the test results and discussion that the proposed device is an efficient, economic and reliable energy harvesting system and could be applied to civil engineering structures.

 

The complete paper.

[J.C.MacSwell]

The authors are not harnessing energy from vortex shedding but, as noted in the extract, from wake galloping. Given that they have generated energy in wind tunnel tests the technique appears to be valid both theoretically and practically.

 

Hyung-JoJung, Seung-WooLee "The experimental validation of a new energy harvesting system based on the wake galloping phenomenon." Smart Mater. Struct. 20 (2011)

 

Abstract

In this paper, a new energy harvesting system based on wind energy is investigated. To this end, the characteristics and mechanisms of various aerodynamic instability phenomena are first examined and the most appropriate one (i.e. wake galloping) is selected. Then, a wind tunnel test is carried out in order to understand the occurrence conditions of the wake galloping phenomenon more clearly. Based on the test results, a prototype electromagnetic energy harvesting device is designed and manufactured. The effectiveness of the proposed energy harvesting system is extensively examined via a series of wind tunnel tests with the prototype device. Test results show that electricity of about 370 mW can be generated under a wind speed of 4.5 m s − 1 by the proposed energy harvesting device. The generated power can easily be increased by simply increasing the number of electromagnetic parts in a vibrating structure. Also, the possibility of civil engineering applications is discussed. It is concluded from the test results and discussion that the proposed device is an efficient, economic and reliable energy harvesting system and could be applied to civil engineering structures.

 

The complete paper.

 

 

 

Fair enough, but I highly doubt the accuracy of this statement at face value (bolded by me)

 

"These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first"

Edited June 13, 2011 by J.C.MacSwell

[Ophiolite]

Fair enough, but I highly doubt the accuracy of this statement at face value (bolded by me)

 

"These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first"

You think their experimental mehodology was flawed? In what way?

[J.C.MacSwell]

You think their experimental mehodology was flawed? In what way?

 

No idea on their methods, but I find that particular statement in their conclusion to be incredible...or perhaps something was lost in translation.

[Ophiolite]

No idea on their methods, but I find that particular statement in their conclusion to be incredible...or perhaps something was lost in translation.

Right, so you are basically using the logical fallacy of Argument From Incredulity. The apparatus is described in section 4. of their paper, as are there experimental results, which showed power being generated. Unless you have something more substantial than your own belief system to offer up, I shall provisionally go with what is revealed by the experimental data.

[J.C.MacSwell]

Right, so you are basically using the logical fallacy of Argument From Incredulity. The apparatus is described in section 4. of their paper, as are there experimental results, which showed power being generated. Unless you have something more substantial than your own belief system to offer up, I shall provisionally go with what is revealed by the experimental data.

 

I haven't read the paper but...if you choose to believe that the experimental data might support:

 

 

"These induce a lifting force on a cylinder in the path of these eddies - but only if the two have the same diameter and the second cylinder is three to six diameters away from the first"

I'm guessing they don't have enough data to prove that statement. I don't think you should take it at face value, even temporarily. (It may very well be a misquote but you go ahead and believe it "provisionally", so as to avoid any personal incredulity)

Edited June 14, 2011 by J.C.MacSwell

[Ophiolite]

I think I'm done here. You reach your conclusion without even reading the paper! No more to be said.

[J.C.MacSwell]

I think I'm done here. You reach your conclusion without even reading the paper! No more to be said.

 

 

I disbelieve anything I know is untrue from experience and basic science principles.

 

The paper may have some merit, but that statement is untrue.

 

If I showed you a paper with an untrue statement that you could understand I doubt you would accept it at face value.

 

At least I would hope not, whether you read further or not.

 

If it stated that a planet of 10,000 miles diameter could stay in orbit, but only if it was between 100 and 200 million miles from a star, would you accept it "provisionally" at face value? Do you really need to read further to find that statement outright wrong or not really what they meant?

Edited June 14, 2011 by J.C.MacSwell

[Ophiolite]

The statement is based on observation and experiment. Your counter statement is based on personal belief and incredulity. I'm not a creationist: i don't like creationist logic, regadless of what field it is applied in. Now tell me specifically which basic physics principles you think it violates.

[J.C.MacSwell]

The statement is based on observation and experiment. Your counter statement is based on personal belief and incredulity. I'm not a creationist: i don't like creationist logic, regadless of what field it is applied in. Now tell me specifically which basic physics principles you think it violates.

 

 

 

Oscillating lift results from instability in the wake behind a cylinder. It is a well known and common phenomenon in both turbulent and laminar (upstream) flow.

 

To claim lift does not happen in the wake of another cylinder except in very specific and limited circumstances is not credible. It would take an infinite amount of experiments (rule every other possibility out) while getting no lift to support that claim.

 

Did you actually read the statement? It says there can be no lift in a cylinder in the wake (vortex street) of another unless it is identical in diameter and even then only while between 3-6 diameters distance downstream. Do you not think it might be a misquote, typo, translation or transcription error or there is something wrong or missing...?

 

Not convinced? Hold two 1" broomsticks out the window of a car, one behind the other, the second covered loosely with a 1.5" plastic pipe, but secured so that it will not slide off. Accelerate until the pipe flutters.

 

(When did you stop believing creationist theory? Is it fair to assume you accepted it, when you first heard it, on a "provisional basis" until you were convinced otherwise? Or did you, somewhat ironically, doubt it immediately using "creationist logic"?}

Edited June 15, 2011 by J.C.MacSwell