Wind Definition and 861 Threads

Homework Statement The doorway in the previous question measures 1.06 m x 2.04 m, and the wind blows parallel to the wall surface at 3.89 m.s-1. Calculate the force pushing the curtains out of the doorway. The density of air is 1.29 kg.m-3. Known data: A = (1.06m)(2.04m) = 2.162 m^2 v(wind)...

Hi, I'm currently in High school so I'm uncertain whether this could be feasibly possible. I read on another thread that Wind Turbine's produce too much drag to actually be beneficial to your car and energy. BUT, they all discussed the wind turbine being on the top of the car. I was thinking...

As a hobby for the last couple of years, I've been designing various theoretical wave and wind generator devices. One of the primary criteria is that the electrical power generation components have to be easily accessible. For wave power, electrical power generation has to be on shore not in...

My parents were driving over the weekend with the windows open and I came up with another bunch of questions. With the windows open, would you use more gas than with them closed? I figured that when the windows are open and wind is blowing in, the wind is pushing in the opposite direction that...

Hi everyone, I am new and I hope I'm putting this in the right section. I am currently a Sophomore in High school and I am building a wind tunnel. It's not for a class but rather its is like an independent study. I have been into planes pretty much all my life and I am hoping to get a pilots...

Homework Statement A bird can fly in still air at 100km/h. The wind blows at 90km/h from W(x degrees)S. The bird wishes to return to its nest which is due E of its present position. In which direction, relative to the air, should it fly?My textbook says that the velocity of the bird relative to...

Homework Statement In point form, outline the process through which electricity is generated from a wind turbine, highlighting the energy transformations that occur. Then state an advantage for this type of electricity production that have not already been discussed in the lesson. Homework...

Homework Statement A plane is taking off from an airport directly west of the airport it wishes to touch down in. The plane in still air can travel with a constant speed of 730 km/h. If a wind is blowing constantly at 92 km/h [45° S of E], at what angle must the plane fly to compensate for the...

I'm doing a school project in which I'm building a wind turbine. The next step for me is to choose a generator but I'm not completely sure what is right for me. I expect to come up to 300 rpm as an average and need the required voltage to for a car battery, which is around 14.4 volt. My...

Homework Statement Choose one form of electrical generation and in point form outline the process through which electricity is generated and the energy transformations that occur. Homework Equations NA The Attempt at a Solution Hi, I am done my work and I used two reliable sources. This...

I am making a small wind turbine for my A-level RMT and wondering what kind of generator I need to charge a 12volt battery. The turbine is a vertical axis savonius turbine that will probably be about a meter high and half a meter wide. I know I can use permanent magnet dc motors and someone...

I created a model on autodesk inventor of a concept model kite that would stay in high altitudes and take in wind energy through the cone opening. Is there any advice you can give me about the aerodynamics of this model? (There are balloons that provide lift above the wings, and I want the...

Homework Statement I have a strip of foil with an area of 10 square cm and a mass of .561392 grams. The length of the foil is 5 cm and the width is 2 cm. The foil is hanging from a pivot point at the very top. The foil rotates 17 degrees backwards from where it started. The foil is in a sealed...

Homework Statement Using a wind tunnel to measure force and velocity at different drive %, we obtained some data for drag. We used one dimpled sphere and one smooth sphere. There are a couple of questions I am stuck on. "The force you have measured is known as the drag force and can be...

My physics teacher said that the northern lights are the product of charged particles coming from the sun and interactign with our atmosphere. I believe he said that these are deflected by Earth's magnetic field and directed towards the North and South poles. When I look at pictures on this...

I'm reading about solar wind and the effects it has on Earth. The charged particles from the solar wind have the potential to affect power grids which can cause outages. I know that it is related to electromagnetism, but how exactly does this happen?

I am a 3rd year integrated Engineering Student. For our 3rd year project we decided to make a portable generator to power laptops that were previously donated to an isolated off grid village in Nepal (for educational purposes). The laptops are currently sitting in rice bags and not being used...

Hi everyone, I am currently doing my Computer Science A-Level project and I'm thinking of simulating a wind tunnel but I am also having a really hard time figuring out how to start. I am programming it in Visual Basic (XNA) and using Blender for models. Could anyone guide me in the right...

Hi, I am designing small power wind turbine with output power 3kW. I would like to ask about the rotational speed dependence on the load connected. I know when generator is open circuit it rotates freely. But what about when the load is connected? Does it slow down the rotation? Because, when...

Hi, I am designing vertical axis wind turbine for generator with 3kW power. Prior to make big blade I have designed small 3D printable version to test. I want to concentrate the force of wind into one point by making specific blade .It would make the blade rotate even after wind passes. That...

Homework Statement A pilot flies a plane from A to B, 400 miles due North of A. If a Westward wind of ##20 mph## is present, determine the direction the pilot needs to aim the plane relative to the air and the speed at which he needs to fly the plane in order to arrive at B in two hours...

i was wondering if anyone had a site that catalogued windspeed effect on heavy objects? I found several sites that talk about trees and shingles, I'm interested in flower pots and deck boxes. If someone could shoot me an equation would allow me to calculate various objects

I'm building a model wind turbine. I'm using thttps://www.vernier.com/products/kidwind/wind-energy/kw-wth3/ as the hub/the base. That's the only kit I'm allowed to use. I'm supposed to decide on the blade size, etc. THE RULES: . Students will will sign up for a time slot and test their own...

Could multiple, smaller rotors on a wind turbine (on the same shaft) be more effective than a single, larger rotor? Why do most wind turbines have only one big rotor? I was thinking about doing a science fair project on this topic, but I have been unable to find a conclusive answer to this...

I'm a civil/structural engineer and I was just recently thinking about one of the biggest issues for maximizing the efficiency of a wind turbine - the structure itself. The mega turbines that engineers want already have foundations of titanic proportions because as we all know, flag pole...

Hi all, I am trying to design a open circuit wind tunnel, and I've got to the point where a fan should be selected. However, I am not familiar with fans at all, so I am wondering if you could help me! My understanding is that the fan selection process is quite similar to the pump selection...

Hi guys Does anyone here got the JIS-B8830: Wind Load Assessment book in English version? I've tried to get it from online and from bookstore but only Japanese version is available. thanks guys

Hello, I made a scale horizontal axis wind turbine that I would like to connect to my phone to charge it. I am trying to decide which motor to buy. Here is my plan and question: Plan: The wind turbine uses a 12 volt dc motor so that when the wind makes the motor shaft rotate there is a...

Hi, I'm trying to build an auto-sufficient station, this is my "blueprint" for mounting everything together : https://goo.gl/photos/4KLmhUc9EDccMPkYA and I would like to know if it was possible to calculate the voltage and intensity entering the Charge Controller without measuring it, if...

I think it is about 90 degrees off but I never thought about wind direction too much. I guess let's say the wind is coming from the NE and there is nothing behind the flag so it's on a field. I know a windcone is 180 degrees so opposite wind direction.

I want to build a computer simulated wind tunnel. I have experience building physics simulators. I undersand that there are already some existing free wind tunnel simulators out there, but do they work at supersonic speeds? I want to predict the drag coefficient of various rockets and bullets at...

I try to understan this article: https://en.wikipedia.org/wiki/Reynolds_number What does "... such as between an aircraft model in a wind tunnel and the full size version." mean? Why cannot we use a full size version in a wind tunnel or why cannot model be full size? Thank you.

I was wondering if placing something (cheap) in front of a wind turbine to redirect more wind towards it would be worth it or should I just place more (expensive) turbines?

I'd like to experimentally simulate air flow turbulences around obstacles. Building the obstacles in one thing, but providing a well characterised flow (and mix it with something visible like smoke...) is something else. In general, I think the whole idea is easier to acomplish compared to fluid...

Hi! I would like to submit a model glider to a CFD wind tunnel so I can determine what would be its optimum glide ratio and forward speed at this incidence. I am not supposed to know in advance the range of speed this glider can fly (between stall and structural damage), so the speed I will...

Homework Statement A small airplane wants to fly from A to B which is 200 km due south. The wind is blowing towards the east at a velocity of 50 km/h. If the airplane can move through the air at 300 km/h, find the direction the plane should be heading; the speed of the airplane relative to the...

In a nutshell, does Newton's "action = -reaction" law apply to massless particles? If a spaceship directs a condensed light beam on its own heat-resistant photon sail, what would happen?

For a school project, I need to know how much less wind resistance a round skyscraper will have compared to a standard rectangular one. You can assume the skyscraper will simply be a generic elliptical shape, somewhat similar to an egg. Answer doesn't have to be extremely specific, I just need...

Not really a homework question but this is probably the best place to post it. I'm interested in what people think about the following experiment and the wording of one of the follow up questions that came with it. It was set as part of UK GCSE Physics coursework for the 14-15 age group. 1...

To approximate windspeeds we normally use the natural logarithm relation: u_air = V ln [ (z-d) / z_0 ]Where: V - Characteristic speed, constant z - height from the ground z_0 - roughness length, constant d - zero plane displacement, constant The Betz limit tells us that in theory that the max...

By noting the direction of the wind, the taper of the blades and the direction of rotation, it is obvious the turbine blades are facing the wind. On the other hand if you blow on a pinwheel while holding it loosely, it turns so the blades are away from the direction of the wind. Does anyone...

I need 250 m/s of airflow speed in a wind tunnel. I can assume for this purpose, the test section of the wind tunnel has uniform flow. However, the wind tunnel can only generate a flow rate of 100 m/s but the pressure can be increased. I am drawing a blank on how could a generic boundary layer...

Why don't the electric generator mount closer to the ground. The advantage I can think is that it is easy to maintain(no need to climb) and reduce weight(reduce tower cost), however the extended shaft will cost more. Does the longer shaft cost out weight the easier maintenance and generator...

I was surprised at the number of people thinking they should "ride out the storm" when Hurricane Mathew moved up the coast. They are assuming that because they've been in a cat 1 or 2 that a 3 or 4 is nothing to worry about. I was trying to explain to someone that force is not linier with...

If a sailing boat is running before the wind, i.e. with the wind exactly behind, is it possible for it to go faster than the wind? If one thinks of a wind generator on the boat it could perhaps operate an electric propulsion motor to give any desired speed? But what about the apparent wind when...

Hi, I am curious as to the effects of wind on a moving person. If a person is walking at 4 mph and they encounter a 10 mph headwind, would the person feel the wind about the same as if he/she is standing still and is facing a 14 mph headwind? Likewise, if a person is running at 7 mph and...

I am trying to figure out how to calculate the boat velocity using wind speed and wind direction. I have tried to find sources online but this is the only useful site I managed to find: https://sites.google.com/site/yoavraz2/sailingboatspeedvs.windspeed Unfortunately it has been a while since I...

Homework Statement Determine the forces at the 3 hinges of closed gate with a wind pressure of 700Pa on the gate. Mass of gate = 236kg wind pressure = 700Pa (apllied perpendicularly to the gate) gate dimensions: 4.1m high, 2.45m wide Distacnce from bottom of door to centre of hinges...

Hello, could someone explain some of the factors, or the calculation, for determining wind turbine cut in speed? I am talking about small wind turbines using with a single bearing on the rotating axis and a permanent magnet generator. A lot of literature targets a cut in speed of 3 m/s without...

In class, of all the shapes we tested, the pinwheel won in the total amount of current and voltage, power generated. (used a regular fan and blew a bunch of different blade designs) Question is, why don't we see pinwheels designs for turbines? Where else can I look for turbines designs? Thanks.