Wind Definition and 829 Threads

http://www.youtube.com/watch?v=AuYFcjBmMJ0&feature=relmfu at time 34:35. He says it depends on how fast the air is flowing by? So does that mean the velocity of sound in the equation f=nv/2L change? How are the different sounds produced?

Homework Statement If a big star gives of wind , forming shock and then a bubble .. And then this bubble is driven by pressure Also as the bubble expands the surrounding mass gets added to it Does it make sense for the Total energy to increase ? Homework Equations The Attempt at a Solution

Hi was wondering if anyone knows how to calculate the tension in a overhead conductor say 'Dog' conductor over a 100m Span with a wind of 900Pa given its properties are as below 'Dog' Conductor properties Diameter = 14.15mm Weight = 0.3965kg/m Area = 118.8mm^2 CBL = 32.7kN Expansion...

I don't know much on these kinds of things but I was just sitting here thinking with my fan on... So particles or atoms or whichever heat up when they move faster/shake faster right? Why is it when the wind hits me I cool off? I assume the wind would speed them up even more right? I feel...

Top down visual of near live wind trails in the US. Really neat! http://hint.fm/wind/ Now we just need it overlayed on google maps!

Hey community! First I'd like to say that this is just a concept. There are probably many faults in this idea since I'm only 16. Basically, I was wondering if it would be possible for a car that runs purely off of wind/electricity. My concept would completely eliminate the need for gas...

Dear All, I'm in a bit of a pickle. I have recently booked out the local wind tunnel in order to run some simulations on three home made model wind turbines. I am aware of how to theoretically calculate the available power (0.5*p*A*V^3) and that P=Tw (Torque * Angular Velocity). Angular...

I am planning on building an above ground storm shelter that will be 16' x 16' by 8'. The footers will be 24" W by 12" D with 4-#4 rebar. Insulated Concrete Forms (ICFs) will be used for the walls then a 5" floor slab. Concrete space of the ICFs is 6.5" or 8" or 10" defending on someones...

It is a puzzle to see so many of the wind turbines that are idle. Even in active wind farms, such as at Altamount Pass, it is usual to see at least 20% of the turbines idle. Older installations are usually idle as well. Why is this? Hydraulic turbines routinely run flawlessly for decades...

Against the Wind One windless day you ride your bicycle at 25 km/h for one hour on a flat road. The next day, you ride 5 km/h into a 20-km/h headwind for one hour on a flat road. Assuming that the force of the wind (the primary "friction" in this case) scales with the square of the...

Hello, a friend of mine has a "revolutionary" idea about harvesting wind power by using a "translational turbine". however, it all sounds silly to me. this is what it should look like: is this a good idea for a wind "turbine"?

If i use a certain amount of energy/work - let's say 0,36 J - to wind up an old alarm clock, will the mass of the clock increase, or will the clock just get hotter somehow?

I am mechanical engineer and working on a project of electric car havin a wind mill on the top. i am using 7 lead acid batteries and a DC series wound motor. The car has a wind mill for the recharging of the batteries. I have read other thread on this forum which states that the wind mill on...

Hello, i am Fluent beginner..im doing thesis about aerodynamics on solar race car.. have to study about its drag and lift coeeficient.. i need help about how to 3D mesh the car and the wind tunnel.. now i have draw the car model as one part and the big square as wind tunnel as another...

can anyone help how to build small wind turbine system to generate 2KW power using MATlab simulink..??

Homework Statement Assume all speeds are constant. (a) A plane flies at speed vstill = 203 km/h in still air. Now, there is a wind blowing at speed vw = 77.6 km/h, with its direction at 30.4 degrees to the east of north. If the pilot wishes to fly due north with the wind blowing, find: - θ...

Hello everyone, I've found these forums extremely helpful in the past and I've decided to create an account in order to answer a question that has been going in my mind and I can't seem to find the answer. The power a wind turbine can generate can be derived from the equation: Power =...

Hello! As part of a project related to dam overtopping induced by wind (wave run-up and wave set-up), I am looking for information on how to calculate fetch lenghts for a reservoir. I would appreciate any information about it. Thanks!

Hey I am making a game with basic a projectile that includes gravity and wind and I don't know how I can control the wind direction and power. Here is what I've got without wind: Setup: x = 0 /// x starting position y = 0 /// y starting position r = 10 /// radius of projectile time = 0...

Howdy - We're a small nonprofit that hosts a single annual event. For advertising this event we construct a large sign on a hilltop that's visible from the nearby highway. In years past this sign would last a few weeks before it would be destroyed by wind. Obviously our guess on how strong...

Homework Statement Two sites are being considered for wind power generation. In the first site, the wind blows steadily at 7 m/s for 3000 hours per year, whereas the second site the wind blows at 10m/s for 2000 hours per year. Assuming wind velocity is negligible at other times for simplicity...

Hello, I am doing research on on wind turbines and especially on offshore wind turbines for my MSc dissertation. My first degree is on electrical engineering so I have a basic knowledge on the matter I believe. I am looking for some books that can provide an in depth analysis on the...

Homework Statement A large kite of mass 3.8kg is flying through the air on a windy day. Currently, the tension from the string on the kite has a magnitude of 8.7N at an angle θ=33.7 degrees. The current acceleration of the kite has a magnitude of a=6.28m/s/s at an angle \Phi=38.7...

Hi What is the minimum kgf (or N) of a magnet to hold a 4m x 2.5m door? The door will be outdoor and wind can hit it. The function of the magnet is to keep it open. Best regards josh

In a tube (open at both ends) that's vibrating at its fundamental frequency, is the air pressure the ambient air pressure at both ends and higher in the middle, lower in the middle, or can it be either higher or lower in the middle? Why? If the same tube is vibrating at the frequency of its...

I understand that in theory one can adjust the blade pitch or the speed or the yaw to control a wind turbine. Every time I do a search on turbine control this is all I come across. However I want to ask the question at a more "actual" level. What actually happens. Do they use PI control...

Hello, As we know, when you blow over the neck of a bottle, it resonates at a certain frequency. I want to build a cylinder that will resonate at a certain wind speed: 4 mph or about 1.78 m/s I definitely know how to find the resonant frequency of a cylinder. However, I'm not sure what...

Hello all, i doubt this but is there anyway now or in the future to increase ion wind to where it acts like and has the same strength as regular wind?

Hi guys, I have been trying to measure the drag characteristics of a wind tunnel model by using a pitot-static tube set up. From which the transducer will output to me the stream-wise velocity profile based on the pressure differential measured. Following which, in order to evaluate the...

the problem is with b. and c. but I would like verification on a if possible, thanks! Homework Statement A cabin lays on a smooth track (so friction can be disregarded) the wind exerts a pushing force F=\gamma u u is the relative velocity between the cabin and the wind. the wind's velocity is...

what is the net force on the roof if its area is 320 m^2 and is flat? I don't even know where to start.

I am doing a wind tunnel experiment on aerofoil. So i need some idea to mount my aerofoil in the test section. The aerofoil is made of acrylic. So which type of stick will suitable for my aerofoil mounting. The configuration as shown in picture that attached. (Picture taken from google image).

i don't know if i am in right part of forum. i want to build some sort of wind turbine for a school project. all the diy project are 6 or 9 coils with 8 or 12 magnets. the coils are on non magnetic board and the magnets on steel plate. why on steel, the steel plate increase the total...

For my research purpose, I made a wind tunnel which has 0.6m rectangular section [0.2X0.2sq. meter] and 1.4m long diffuser section having porous top [top wall angle is 20deg] as follows: Wind tunnel speed is 15m/s. Even using 20deg inclination of porous top wall, there is no flow...

My friends and I were having a discussion about falling and new the whole rate of acceleration and what not, but where unsure how to account for A) wind resistance and B) the act of jumping. So assuming that we "jump" from a 7th story building, and assuming that each story is 10 feet, and all...

Michelson Morley experiment was sought to find out Earth's motion through ether, which allegedly produced ether wind. Thus the time required for two rays of light would be different, thereby producing interference pattern. Since Earth revolves arouns sun, and sun revolves around something else...

Homework Statement Imagine yourself seated at the center of a spherical shell of radius 3 X 10^8 meters the inner surface being diffusely reflecting. A source at the center of the sphere emits a sharp pulse of light, which travels outward through the darkness with uniform intensity in all...

Hello All, I'm currently in the process of designing a numerical model for a vertical axis wind turbine, more specifically, a straight blade giromill. I'm currently having trouble because depending on the variables I choose, I can produce more power than available from the wind. My...

Belts and pulleys for WIND TURBINE ? Hi, I have been working on a Vertical Axis Wind Turbine. The blades I am able to fabricate produce more torque than speed. I am adding a synchronous belt drive transmission. The current configuration is 1 rpm at the input and 7 rpm at the output. I have...

Homework Statement If wind blows at 35m/s over a house, what is the net force on the roof if its area is 240m^2 and is flat? Homework Equations P=F/A and P1 + 1/2pv^2 = constant The Attempt at a Solution I have no idea on how to find pressure, because if I sub it into P1 + 1/2pv^2 =...

Homework Statement In a tornado or hurricane, a roof may tear away from the house because of a difference in pressure between the air inside and the air outside. Suppose that air is blowing across the top of a 2200 ft2 roof at 136 mph. What is the magnitude of the force on the roof...

Please Help! In dealing with wind induced forces, caused by vortex shedding action over a circular cylinder, we must calculate the parameter "Kw" (effective correlation factor), which depends on "L/b", "L" beeing the "correlation lenght" (Eurocode). Is there any method, analytical (or...

So, I am totally not an aerodynamic engineer, but my boss - an organic chemist- thinks we should get a wind tunnel to test some new polymer coatings that our research group developed. In researching and calling around to companies that make wind tunnels, I got a question that i have no idea how...

Homework Statement If you jumped out of a plane you would begin speeding up as you fall downward. eventually due to wind resistance your velocity would become constant with time. after this occurs the magnitude of the force of wind resistance is a. slightly smaller than the force of...

Intuitively I would say no because it seems like a big call but at the same time the high energy effects rely on the interaction between magnetic fields and gas don't they? Any tips or just an idea of where I can find out would be awesome

Homework Statement 1. Homework Statement A 373-kg boat is sailing 13.0 ° north of east at a speed of 2.00 m/s. 32.0 s later, it is sailing 33.0 ° north of east at a speed of 3.90 m/s. During this time, three forces act on the boat: a 33.1-N force directed 13.0 ° north of east (due to an...

Homework Statement An airplane is heading due south at a speed of 500 km/h. If a wind begins blowing from the southwest at a speed of 100 km/h, calculate the velocity of the plane relative to the ground, and how far off course it will be after 10 min. if the pilot takes no corrective action...

use of wind powered turbine in cars ?? helloo.. I'm just thinking to build an wind turbine powered car using with electric motor like an hybrid car .. there are certain question arises in my mind are .. that the use of turbine as a source of energy will be efficient or just theoritical concept...

i am making a wind tunnel in order to test aerodynamics of 1/24 scale cars. i am having two problem: 1. i am not sure what wind speed at that scale to represent 100mph. 2. i am using a fan that has an outlet wind speed of 19.4 mph. i tried to increase wind speed by decreasing the outlet...

Hi all, I'm studying for my and I've been trying to do one of the past exams from the University of Auckland. Unfortunately I'm not so clever so I'm asking for some help Two design proposals for a wind park have been made. The first design uses 10 turbines, each with a height of 90m and a...