Wind Definition and 829 Threads

Hi, The extract below is from a paper on ARXIV that I was reading recently. In this paper (and a number of others that I have read recently) there are a number of references to "wind" in a cosmic context. What is this wind? I have tried to do a number of searches to try to find out, but I can't...

Homework Statement A pilot with an airspeed of 500 km / hr wants to fly from City A to City B (which is exactly 700km North of City A); however, there is a wind from the West at 50 km / hr. In which direction should the plane fly in order to arrive directly at it's destination. Homework...

Hi all, This question just occurred to me: Whether a falling raindrop in presence of a uniform horizontal wind (ideally speaking) has a curve trajectory or a straight line? Assuming the wind force is constant, the velocity of the raindrop in horizontal direction will keep on changing since there...

My kids have some question to ask so bear in mind that they are in grade school. Hi, We have been talking and learning about motion and studying examples to understand concepts. One discussion was about what happens when you take a fan and blow it into another fan. The first fan would cause...

I have read articles regarding Chinese junks which utilise rudders made of rubber, and they usually have diamond shaped holes in them. These articles claim that the holes provide better handling of the junks compared to a full rudder without holes in them. What are your thoughts regarding how...

Hi Readers, I have just began learning about a few types of supersonic wind tunnels. I am more concentrated on the continuous type where the air on the inside can be reused using coolers, fans, vanes, nozzles, diffusers, etc. But can someone give me a few types of these continuous supersonic...

I have done an experiment recently and found that there seems to exist a linear relationship (the R-squared value closest to one compared to quadratic fit, although they are pretty close) between the distance from the fan and the wind force. At distance zero there is a certain magnitude the...

Homework Statement Homework Equations P=FV The Attempt at a Solution To calculate the mass of wind swept by turbine in a second, I take 2000m2 ×10ms-1×1.3kgm-3.Then, to calculate the force I multiply the answer with 10ms-1. Since they want the power and the yield is 50%. I multiply the...

I understand that when wind hits the blades straight on it spins for the same reason a pinwheel spins when you blow straight at it. But when wind is hitting the "cutting" parts of the blade how does air foil design help there? Wouldn't the lift generated by the air foil not matter since the...

Hello all my friends...! This is my first discusion about this type of discusion , so let make long short story i read people from 2009 want to find way how to use wind in car producion or self use... I was thinking let me try to find way to get solution on that problem so after long thinking ...

Hi, this is my first post. I teach high school physics and am trying to build a simple wind tunnel. For my first attempt I used a Utilitech high capacity 20 inch fan (nominal 6800 CFM) but the resulting air speed was disappointing – only 4.8 m/s. What type of fan would be better? I was...

Hello Guys , I want to have my HUD displayed on my car's rear wind shield so that the driver just behind my car has an idea of my driving (Hypermilling) :cool: I have been looking for a possibility to do this but till now I only saw devices that projects the display on the front wind shield...

I posted this on Eng-tips and no replies yet:( I'm trying to design an as-simple-and-cheap-as-possible supersonic wind tunnel using an air compressor (this even possible? given the energy losses from shock waves...). I have access to a Porter-Cable 150psi, .8hp air compressor. Questions: 1...

Sounds pretty good: http://www.theverge.com/2015/5/16/8615089/vortex-bladeless-wind-turbines-shake-to-generate-electricity I like this particular idea a lot. With no blades, these take up much less space, and the claims about them being 50% less expensive to make, and lower maintenance, seems...

When you are driving and open the window, wind blows into it, but what causes the perpendicular direction of the air's motion to your direction of travel into the car? For instance, a bus. A bus is basically a rectangular prism with parallel window sets on either side, completely parallel to...

I'm looking for a two element 3D wind tunnel app. Any out there that will run on a PC?

Hello.I need help with wind tunnel.The test section is 2m x 2.5 m x 5 m long.How do I work out size of inlet cone.Thanks in advance

Homework Statement A pilot points an aircraft due west, while the wind blows towards the NNE (45 degrees north of east). The resultant velocity of the aircraft over the ground is 64 m/s, 25° N of W . (a) At what speed does the wind blow, and (b) what is the speed of the plane with respect...

Hi All! as you can see I'm new here! i signed up in order to ask for a wee bit of help with my thesis! (now don't get me wrong I am not exactly asking anyone to write it for me!) I've found myself at a small bit of a loose end here, as a mechanical engineering student i am perfectly capable of...

Given a certain sized Savonius Wind Turbine, for example, using a 5 gallon bucket (about 12 inches in diameter and 14 inches tall) cut vertically in half, the standard configuration has the two "scoops" either touching at the central vertical axis, or partially overlapped. Would moving both...

Is there a limit to the amount of energy which can be extracted from the wind? There are a huge number of windfarms springing up around the world.. all taking energy from the wind. The assumption seems to be that this is limitless and "free". Clearly this is not possible. The question is (I...

Hi, I was wondering if anyone here had any experience (preferably intimate) with the Weber-Davis solar wind model, i.e. ...

Hello, I have question about wind forces on a human body. (Wind force may be an incorrect phrase.) I have looked at a few other threads but haven't found an answer yet. Thisnisnfor a fictional short story I'm writing for fun. Info - SciFi A character in armored suit is hanging upside down...

I am a skydiving coach and I am trying to figure out how many pounds of force wind moving approximately 120 mph has on something with a surface area of 25 square inches. I know turbulence and compression play into it as we'll but I just want a general formula to figure it out. The object is...

Hi, I have this wind turbine (http://m.ebay.co.uk/itm/251320008073?nav=WATCHING_ACTIVE&skus=Output:12V&varId=550270984212) in the UK, wall mounted about 18ft, its not in the best position, but it still turns pretty fast, enough to hear the blades spinning from inside, and for it to generate...

Homework Statement A wind tunnel is designed to draw in air from the atmosphere and produce a velocity of 100m/s in the test section. THe fan is located downstream of the test section. What pressure is to be expected in the test section if the atmospheric temperature and pressure are -20C...

Hey everyone, I'm a student working on building a wind tunnel with some classmates. I'm in charge of figuring out the drag and lift force sensors. I'm currently looking these two components: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2128260_-1...

I have been tasked to design a controlled descender to be used on a building site to lower tools/rubble to the ground. I'm trying to design a product like a fan descender like that seen at powerfan.co.uk Could anyone help me with the theory side of its operation. Obviously it uses the fans...

Hi, I have a 300-400w wind turbine which generates 3-Phase AC @ 12v 33.33Amps Maximum. The wires are colour coded Red, Black, Blue. I have a 3-Phase AC to DC rectifier which can handle up to 1200v @ 50A. Currently I have it connected like so; Red, Blue, Black. I'm wondering, does it matter...

I'm working on a project now and I'd like to know which type of airflow would power a turbine faster/better straight or rotational? Or will rotational airflow even have any effect on the turbine...? P.S. When I say rotational airflow, I mean circular airflow that rotates in the same direction...

I currently get my electricity from an electric company. I would like to get a windmill installed on my roof to supplement my electricity needs. I want to be able to use the windmill to get as much free electricity as I can, and I would like to continue to keep getting the rest of the...

Homework Statement Basically, a wind turbine's connected to a car alternator. weight of turbine=72 kg length of blade-30 cm. What is required, is the amt of power this wind turbine will produce when the car (to which turbine is attached) is moving at: a) constant speed b) variable speed...

So, my proposition is this: (Note that this is a purely theoretical project, and no models/experiments are necessary.) When a car moves forward, wind moves backward, right (relatively). So if we were to attach a small, retractable wind turbine to the side, connect it to the alternator, we could...

Would it be possible to put piezoelectric devices on the front of a car so that when the car is moving forward, the pressure from the wind on the car and piezo devices produces power to charge a battery? If the wind is strong enough, do you think there would be a considerable amount of energy...

Hello, I could use some help determining what size hydraulic cylinder I need to be able to tilt my turbine tower up. What I have is a 70 ft tower where the first 20 feet weigh 2500 lbs, the 2nd 20 weigh 1700 lbs and the 3rd 20 ft weigh 1000 lbs and the last 10 feet weigh 1000 lbs. For a total...

For my senior design project, I have to reduce the aerodynamic drag of a truck and trailer. I am doing CFD simulations and wind tunnel testing. The dimensions of the wind tunnel (test section) are 94 in long, 13.5 in tall and 20 in wide and a cross-sectional area of 270 in^2 and it could go up...

Hi, I have became confused about a "certain situation" belonging to Bernoulli Principle :a "wind on flat roof situation" more precisely. The big misconceptions on the net didn't make it easier. There are very contradicting explanations from experts on the web. However, I hope to...

How to calculate the force of wind pressure, for example for the surface tilted at 45 degrees? I need to find some serious work related to the wind pressure force calculated for different 3D shapes affected by wind from different angles. Can somebody recommend me the good names, keywords...

Homework Statement During a sustained wind the blades on a two blade horizontal–axis wind turbine is turning with an angular velocity of 5 rad/s. If initially the blades have an angular velocity of 2 rad/s, determine the distance point P on the tip of the blade has traveled in 3.0 seconds...

I'm attempting to design a turbine for a small scale solar updraft tower. It produces between 1-3 m/s of air flow in a 0.3m diameter tower. I'm in need of resources that can guide me on designing the turbine fan. I've already got the Wind Energy Handbook, however I'm not even sure if following...

my question is would a line of wind turbines have a comparable effect to a wind break in reducing wind velocity

I'm currently working on a project about wind speeds, and have come across a roadblock due to my limited knowledge... So I really hope you guys can help me out. When you light a campfire or candle, the heat from the flames cause the air around it to rise, which leaves a "vacuum" for colder...

I've been trying to figure out this problem for hours my whole group and most of the class is stumped. We understand that we need to relate the equations of F=ma, Fd = (Cd*p*v^2*A)/2, Fnet=Fd-Fg. No data is given. The answer is a V=____ equation. Even just an answer to #1 would be very helpful...

Homework Statement As part of a school project, I'm investigating the optimum blade pitch angle for a simple 6-blade wind turbine, powered by the air flow from a desk fan. I have taken power output measurements using angles in 5° intervals from 0° to 30° and found the optimum to be 20° in 5...

Hi people! I'm studying the problem of a house in a valley with a wind at 5m/s. If I'd like to compute Reynolds number here and know if the flow is laminar or turbulent which is the charateristic dimension? The height of the house?

Homework Statement One of my question asks that: How much longer is the flight from airport A to B with the wind as indicated than with no wind... I don't get its meaning. What do I need to solve for this question? Homework EquationsThe Attempt at a Solution

I've recently started working on a wind load calculator. Notice the complexity when overhangs are added to the roof. These load diagrams show the Envelope Procedure for a Gable Roof: Load Case A: Load Case B: If torsional load cases are required then another Load Case A and B...

How do you estimate/calculate how much solar wind a star produces? (Can we even make a passable attempt?) I'm trying to work out whether a fictional exoplanet in orbit around R Coronae Borealis would need a magnetic field (as there appears to now be some debate on a cursory google search on...

I have just begun my power electronics class, but have already seen what an inverter is. My question is: is there a difference between the topologies that function with photovoltaic systems and wind energy ones? Thankyou

Hi guys! I am doing a project for my High School, here in Spain, that is obligatory for everyone. As a love everything related with planes and aerodynamics I've decided to create this wind tunnel. Is approximately 2,15 meters long and it weights around 10 kilos. It is made 100% of wood and it...