User:Hsingh8658/enes100/Bernoulli Effect

Link back to team page.[]

Give instructor top 3 project choice list
1. Bernoulli effect

2. Helicopter

3. Model boat

Write problem statement
To make projects to show the difference between Coanda and Bernoulli effect

Assign Task1
To search about coanda and bernoulli effect. Learn as much as I can about these two effects and to compare them for differences between them.

Compare actual work done to Task1
Rationalize differences

Watched many videos on youtube about Bernoulli's effect and Coanda on youtube. The video that we used for understanding the concept of Bernoulli effect is http://www.youtube.com/watch?v=iDpPnucmjyY The Bernoulli effect is explained using the principle of conservation of energy in this video. Links to other videos showing Bernoulli effect are as follows-

http://www.youtube.com/watch?v=olVJzVadiFs

http://www.ap.smu.ca/demonstrations/index.php?option=com_content&view=article&id=111&Itemid=85

http://www.youtube.com/watch?v=1JuoSJz3SRU

http://www.youtube.com/watch?v=VKNx22phu88 This video was made during the Engineering Expo '09 at University of Wisconsin - Madison. It shows the Bernoulli Effect using a fire hose and a basketball. The fire hose was mounted on a wooden stand and pointed straight up. The basketball was placed onto a wide stream from atop a ladder. The stream was then adjusted finer and finer so that the ball would levitate higher. I estimate the max height of the ball to be ~18 feet high.

This demonstration was put together by the research group led by Ryan J. Kershner, Ph.D.. It was an addition to another exhibit that was put on by Daniel N. Hawk called Micro-Pong, which used holographic optical tweezing to allow people to play the smallest live-action game ever.

I also searched for a plausible explanation of coanda effect, some of the useful links are

http://jnaudin.free.fr/html/coanda.htm

http://jnaudin.free.fr/gfsuav/coanda/index.htm

Week1 Narrative
Upload photos to wikimedia. Upload video to youtube. Convert all spreadsheets, documents, and presentations to wiki format and create wiki subpage of your page for each of them. Link to them here in a narrative that tells a story. High light the problems (engineering problems) you had and how you solved them.



I read about Bernoulli effect and coanda and watched videos about these effects. Links to some of the videos are posted above. In the first video http://www.youtube.com/watch?v=iDpPnucmjyY the bernoulli effect is explained on the basis of law of conservation of energy and explains that movement changes the static pressure. Static pressure is the pressure inside the stream and it is parallel to the flow of the stream. It is measured using a device called manometer which moves with the flow of fluid and which is parallel to the flow. Thus the static pressure within an air stream has to be measured carefully using a special probe. A thin disk must cover the probe except for the opening. The disk must be positioned parallel to the streaming flow, so that the flow is not interfered with. If the static pressure is measured this way within a free air stream generated by a fan or a hair dryer it can be shown that the static pressure is the same as in the surrounding atmosphere. So, explanation of Bernoulli effect used in video will fail in this case as there is no change in static pressure. The equation of Bernoulli's theorem is clear and its predictions are verified, but the real cause of the predicted pressure changes is obscure.

Week1 Peer Review
Go to each team mates weekly summary wiki page. Read their activities and narrative. Then go the associated discussion page. Say something positive on this page. Try some constructive criticism. Add your name and a signature ~ by entering four tildes in a row to create a time and date stamp. Create a new category if another team mate has already commented here.

Assign Task2
Record what you are planning on doing for the team during the weekend between week1 and week2 of the project here.

Going to do more research on misconceptions of Bernoulli's law

Compare actual work done to Task2
Rationalize differences

Went through the page http://user.uni-frankfurt.de/~weltner/Mis6/mis6.html and tried to understand the misconceptions of Bernoulli's law. Found out that Bernoulli's law is misinterpreted in many cases and some of the videos shown in the first week of this project were not real applications of Bernoulli's law. Also found that acceleration of air is caused by pressure gradients and air is accelerated in direction of the velocity if the pressure goes down. Thus the decrease of pressure is the cause of a higher velocity. It is wrong to say that a lower pressure is caused by a higher velocity and so our explanation of Bernoulli effect in previous experiments were wrong.

Read the text in this link and watched videos to understand Coanda http://www.physics.umd.edu/deptinfo/facilities/lecdem/services/demos/demosf5/f5-12.htm

In one of our previous video we explained that the filling of thin plastic tubing with one lungful air if we keep our mouth away from it is due to Bernoulli effect but I found that it is not Bernoulli effect. When you blow into the balloon, you form a very rapidly moving airstream. Air from the atmosphere surrounding your airstream becomes caught up in the airstream, multiplying by severalfold the amount of air that is being pushed into the balloon. This process is called entrainment. The Bernoulli effect deals with isentropic flow along streamlines, and this demonstration does not fit in this category.

Our explanation of Bernoulli effect for standing of ping-pong ball in air was also wrong.The correct explanation involves the Coanda effect. When the air stream flows past the ball, some of the air follows the contour of the ball and only leaves after it moves a significant distance along the surface of the ball. In effect, the ball is "pulling" the air around its surface. There must always be some reaction force on the ball, which points in the direction of the air stream and upward, holding the ball in the air. This effect can be better understood by following this http://www.sciencetoymaker.org/balloon/links.html

The following link explains the functioning of vocal folds. The movement of folds is due to Coanda and not Bernoulli's effect. http://www.physics.umd.edu/lecdem/services/demos/demosf5/f5-03.htm

I also researched about flight of airplanes and found that the conventional or standard explanation of aerodynamic lift states the higher streaming velocity at the upper side of the airfoil as cause of the lower pressure, due to Bernoulli's law. But a higher streaming velocity is the effect of a lower pressure and never its cause. The cause of the aerodynamic lifting force is the downward acceleration of air by the airfoil - which depends on the angle of attack and its velocity. In relation to the airfoil the normal acceleration of the air in case of curved streamlines must be regarded which results in pressure gradients perpendicular to the streamlines and reaction forces acting perpendicular on the deflecting surfaces. The nature of the actual lifting force on a real airplane wing is complex. One can argue that the Bernoulli effect creates a pressure difference between the top and the bottom of the airplane wing. However, this pressure difference, in the absence of air deflection downward cannot explain the lift required to keep the airplane up in the air. According to Newton's third law, there must be deflection of the air downward due to either or both: deflection of the air due to the angle of attack of the wing, and shedding of vortices at the trailing edge of the wing.

A better explanation of airplane wing lift (as well as a number of other demonstrations generally ascribed to the Bernoulli effect) involves the Coanda effect and downward deflection of the air passing over the wing. According to the Coanda effect, the air flow follows the contour of the wing, ultimately moving at an angle downward from the rear of the wing. The reaction force acting on the wing provides the wing lift.

The following link from University of Frankfurt was very helpful in understanding this concept http://user.uni-frankfurt.de/~weltner/Physics%20of%20Flight%20internet%202011.pdf

http://www.regenpress.com/aerodynamics.pdf This link also provided some basic information about winged flight.

I also found the following link which is about 3D aspects and concept of wings. I didn't had enough time to go through whole page but will go over it next week, it might be helpful http://www.amasci.com/wing/rotbal.html

Week2 Narrative
Upload photos to wikimedia. Upload video to youtube. Convert all spreadsheets, documents, and presentations to wiki format and create wiki subpage of your page for each of them. Link to them here in a narrative that tells a story. High light the problems (engineering problems) you had and how you solved them.

I first looked through the link http://user.uni-frankfurt.de/~weltner/Mis6/mis6.html and then used my mathematics textbook to understand the derivation of Bernoulli's law. Then I did some more research on misinterpretations of Bernoulli's law and find plausible explanation for the concepts which were explained using those misinterpretations. I also looked through dynamics of flight.

Week2 Peer Review
Done

Assign Task3
Record what you are planning on doing for the team during the weekend between week2 and week3 of the project here.

Will go through following link http://www.amasci.com/wing/rotbal.html and also will try to get more information about Coanda effect and will find misinterpretations of Coanda effect, if any.

Compare actual work done to Task3
Rationalize differences

I first went through the incorrect theories of flight of an airplane and uploaded some pictures of incorrect theories to wiki commons and then to wikiversity. Then I read the link http://www.amasci.com/wing/rotbal.html thoroughly to understand the 3-D aspect of flight. I found that controversy arises because we are taught about the flow patterns around two-dimensional airfoils and then we apply those concepts to 3D wings. The behavior of 3D wings is fundamentally different than the behavior of 2D airfoils. Going from 2D to 3D is not a trivial change. This page very well described the flight on the basis of action reaction forces by explaining the formation of vortices. An example of a person walking on a series of Helium balloons is used to explain flight of airplane and formation of vortices. An aircraft does much the same thing as the person walking on balloons does to balloons: it remains aloft by shedding vortices: by throwing down a spinning region of mass. This mass consists of two long, thin, vortex-threads and the tubular regions of air which are constrained to circulate around them. Vortices inject momentum into air which as a result moves downwards. They employ "invisible disk-balloons" to stay aloft.

Finally, I went through the following link to understand more about Coanda effect.

http://www.meridian-int-res.com/Aeronautics/Coanda.htm I learned about many applications of Coanda effect, some of them are- Hydrofoil and Submarine Propulsion Circulation Control Wing The X Wing Helicopter Drag Reduction Spoilers for HGVs (Heavy goods vehicles) The Gurney Flap Dual Cavitating Hydrofoil Thrusters Drag elimination and aerodynamic braking systems for automobiles The NOTAR helicopter anti-torque system The Flettner Rotor Wing The Kline Fogleman Wing Wing in Ground Effect Vehicles The Carr Internal Wing (or Channel Wing) Aircraft The most important and most interesting application of Coanda effect according to me is Circulation Control Wing. The objective is to replace the lift devices on the leading and trailing edges of a wing by use of Coanda Surfaces and slot blowing instead.

Week3 Narrative
Upload photos to wikimedia. Upload video to youtube. Convert all spreadsheets, documents, and presentations to wiki format and create wiki subpage of your page for each of them. Link to them here in a narrative that tells a story. High light the problems (engineering problems) you had and how you solved them.

I started by looking at incorrect explanations of flight of an airplane. Some people explain it on the basis of Bernoulli effect, some on the basis of Newton's third law and some on the basis of the Venturi theory. But all these explanations are generally wrong. They might be right in some terms but they can't explain overall flight dynamics. I found that flight can be best demonstrated in terms of Coanda effect.

Then I worked on 3-D model of flight analogy. I read the following page http://www.amasci.com/wing/rotbal.html and found that The behavior of 3D wings is fundamentally different than the behavior of 2D airfoils and going from 2D to 3D is not a trivial change.

In a 3D world, an airplane produces a downstream wake with net downwash. It injects momentum into the nearby air, and this air begins moving downward. But in a 2D wind-tunnel there is no such downward-moving wake, the 2D upwash must always be equal to the 2D downwash, and the momentum is injected into distant floor/ceiling. Even more important, 3D wings have finite dimensions, while 2D wings act as if they have infinite span. An infinite wingspan gives some strange results; results never produced by finite 3D wings. For example, if a 2D infinite wing should ever deflect even a tiny portion of the oncoming air downwards (deflecting a streamline,) it would deflect an infinite amount of air and produce an infinite lifting force. As a result, a 2D infinite airfoil does an odd thing: it applies a finite force to an infinite mass of air. In response a net amount of air does NOT move downwards (since it has infinite mass.) The incoming and outgoing streamlines remain horizontal. The wing acts like a reaction engine, but an engine where the "exhaust gasses" have zero velocity and infinite mass. This strange effect only applies to 2D airfoils and infinitely long wings, and is never seen with 3D airplanes flying through 3D air.

While studying about 3D world of airplanes, I also came across with terms like Magnus effect http://www.physics.umd.edu/lecdem/services/demos/demosf5/f5-31.htm and http://www.physics.umd.edu/deptinfo/facilities/lecdem/services/demos/demosf5/f5-32.htm. Magnus effect also plays a role in flight of the airplane.

Week3 Peer Review
Go to each team mates weekly summary wiki page. Read their activities and narrative. Then go the associated discussion page. Say something positive on this page. Try some constructive criticism. Add your name and a signature ~ by entering four tildes in a row to create a time and date stamp. Create a new category if another team mate has already commented here.

Done

Assign Task4
I will try to bring whole information together and will finally differentiate between Coanda and Bernoulli effect.

Compare actual work done to Task4
Rationalize differences

I put together all the research and tried to compare and get a general summary of the project.

Week4 Narrative
Upload photos to wikimedia. Upload video to youtube. Convert all spreadsheets, documents, and presentations to wiki format and create wiki subpage of your page for each of them. Link to them here in a narrative that tells a story. High light the problems (engineering problems) you had and how you solved them.

I updated the team page and summary of the project was put on the team page.

Week4 Peer Review
Go to each team mates weekly summary wiki page. Read their activities and narrative. Then go the associated discussion page. Say something positive on this page. Try some constructive criticism. Add your name and a signature ~ by entering four tildes in a row to create a time and date stamp. Create a new category if another team mate has already commented here.

Complete Project Page
Follow the "project done" format.

Start Next Project Week0 activities
During this week you will perform the week0 activities of the next project.

Week zero of the next project, "Model boat" was completed. Watched videos on youtube about model boat and created the team page for that project.