Wind Definition and 829 Threads

I recently have made a wind turbine based on Michael Waters basic design. It has 25 cm diameter and two bearings are attached to the shaft. At first, I have tested by putting it at the top of a ball point pen under a ceiling fan. You can see how it rotated in this video. But when I added the...

I tried a method solving for the force of the wind first which I found to be 2842.95 N. From there I found the torque force using torque = F_wind x d, where I let d = 90ft. This leads to a torque of 77987.8044 Nm. From there I used Tension = torque/moment arm, with a moment arm of 20ft (half of...

I love weather and atmospheric physics! So when I recently read Dune, I couldn’t stop thinking about the “Coriolis Storm”, wondering if such a crazy storm could really exist, ripping around an Earth-like planet at 700 km/h. For me, this became a worldbuilding exercise: What makes the windiest...

this one is our extra credit problem with no instructions. just creative thinking.

How many particles (approximately) from the solar wind reach deep into the Earth's magnetic field every second. Possibly measured in mass?

Why this wind tunnel rotate?

I want to install two retractable patio screens on my patio but there aren't any columns, so I'll need to install a post/column to attach the screens and guide rails to. My concern is making sure I install an adequate post for support during winds. If I can avoid it, I'd like to stay away from...

Hello I'm thinking of how to attack this problem. Outside a channel-inlet, wind is passing perpendicular to the opening with a wind speed of 9 m/s and a fan sucks in a certain amount of air into this channel so that the velocity in the channel is 3 m/s. When the outside air is 0 m/s I have no...

I read that the solar wind is a stream of particles, primarily electrons and protons, flowing out from the sun at speeds as high as 900 km/s, and at a temperature of 1 million degrees. Using the equipartition theorem, I calculate that a proton moving at 900,000 meters per second exhibits a...

Which Umbrella base is the least likely to tip over, Round base, Triangle Base or Square base ? Trying to work out which is the best Umbrella base to have in the garden on a timber deck , Round base, Triangle Base or Square base ? I have noticed my round base Umbrella at home tips quite easy at...

Consider a rectangular tarp with a grommet in each corner, and each grommet is tied to a pole in the ground with a short piece of rope, such that the grommets are basically fixed to the tops of the poles. The poles needn't be at equal heights and the tarp aspect ratio is not specific, in my...

Imagine a wind speed of 'W' (variable), rotating funnel of 'X' diameter that narrows and then conveys flow through a 'Y' diameter, 'Z' length pipe until it hits a 'Y' diameter check valve. What is the minimum cracking pressure needed of the check valve, provided the variables above? I am...

TL;DR Summary: I have a water drop falling with a constant velocity ##v##, since ##mg=\frac 12 C \rho S v^2##. Wind is blowing with a velocity ##u## only in a horizontal direction. What will be its force acting on the drop? I would use this equation ##F= \frac 12 C\rho S u^2##. When I want to...

First, I understand how wind effects aircraft tracking. I can do the calculations involving wind correction angles, effects on ground speed, headwind or tailwind calculations, etc. I teach it in a college piloting program. I am wondering how the ground tract of turn is effected by the wind...

Hi, I am trying to rewind an existing Chinese alternator, it comprises of rotor with 12 magnets and 18 poles (stator), the original design produced virtually no power , aluminium windings have been removed and I have replaced with copper 20 gauge wire, 7 turns per pole, I spin it and nothing...

60 watt tube amp needs a 5k primary and 8 ohm secondary transformer. I have wound voltage transformers on my lathe many times. Audio transformer is no different. Online impedance transformer calculator says, 5k to 8 ohms in 25:1 ratio. Online info says, audio transformer should be 60w x 5 =...

Suppose one forgot to protect outside water spigots against below freezing winter air. If there is a stiff wind, will, as I think, the spigot freeze sooner than if the air is calm at the same temperature? Also, wouldn't the case of calm air actually be more complicated to model because the...

the tldr covers everything I think. I don't expect there will be an analytic solution here lol. but I don't even know where to even begin formulating this problem mathematically. I assume I should find an expression for the initial lift on the blades, multiply by 3 and then model it as a...

I will like the equation describing the amount of wind power available to a wind powered vehicle driving directly downwind. I'm interested in the ideal case so max theoretical power available to a wind only powered vehicle driving directly downwind. I do know what the equation is but I like to...

How was it justified before conducting the MICHELSON–MORLEY experiment to assume that the sun was at rest with respect to the ether? Also, was the ether assumed to have the same velocity with respect to the Earth throughout space at one instant in time, or like wind, with different velocities at...

I drew a FBD but I feel like it's wrong because there are too many missing values. I tried this: Fy = 0 Tcosθ - Fg = 0 Tcosθ = mg T = (1.2)(9.8) / cos(25) T = 12.98 N Fx = ma Fwind - Tsinθ - Fdrag = ma Fwind - (12.98)(sin25) - Fdrag = ma I don't know how to find these missing values. I feel...

Hello everyone, I am reading a book about wind power turbines and found a calculation. I tried it myself and the numbers doesn't match. Here is an image of the data and result. I don't get to the same torque. And also what do you think about the moment of inertia value? Before the data...

Hi, Like many here I watched Veritasium's awesome videos on this*. And like many I found myself having to drag my mind into understanding why it works. The energy explanation makes the most sense to me. Derek explains that the fan is taking energy out of the existing wind - slowing it down -...

So the question was if a plane is going from point A (origin) to point B 400 km directly south of point A at 220km/hr north and there is a wind going 62 km/hr east to west, what angle should the plane orient to go straight from point A to point B? I got something lik 16.4 degrees. The second...

Hello everyone, In trying to better understand how sailboats work, how they can sail upwind (not directly), how the go faster than the wind speed, I have been thinking about the magnitude of the wind force and its equation: $$F_{wind}= \frac {1}{2} \rho_{air} A v_{wind}^2$$ Instead of ##...

Hello all, i posted this on another forum but didn't get much response, I had an 18” centrifugal fan around around and wanted to see if I can push some real air to make a wind tunnel. I'm just a hobbyist, and like to build and modify cars, figured this would be something to look into. Looks...

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Hi everyone. I came across the following brainteaser: A plane travels from airport A to airport B and then returns to A from B. There is no wind, both trips follow a straight line, and the plane flies at constant engine speed. Suppose now that a constant wind is blowing from A to B. Will the...

Hi all, I have some data from an automatic weather station, with recordings of both 2m air temperature and 2m air pressure and also the surface temperature. Is it possible to estimate vertical wind speeds between the AWS and the surface based upon this data? Imagine T_a = 15 degrees and T_s =...

I am trying to fabricate a chime or pipe gong and I want it to have a very low, sustaining tone. In viewing retail products (specifically, Hamacher Schelemmer online catalog item # 90774) I have noticed some products have a slit cut along the partial length of the chime to lower the tone. Is...

how do I calculate static and dynamic pressure for the wind tunnel lab report, drag force, and lift force? Please, anyone? thank you.

Hi guys, thanks for helping me! I am working on a home project that includes a privacy shade for my backyard. I have a 6'x15' vertical shade attached to two portable posts that are held up right by four legs ("X" shaped footprint). the surface footprint of the legs covers an area of 46"x70". I...

Greetings Good People, As the title suggests, I'm having some trouble getting to a 2D model. The process is to select an aircraft (or wing model), and model it as a 2D, 2DOF wing-tunnel model. The aircraft I selected was a Cessna 172. This had a tapered wing, which after some calculations and...

Find the question and its solution below; Ok i realized that we could also use cosine rule here, in my approach i considered the sketch below; ##V_b= 18,125- (2×50×125×cos 135)## ##V_b=164.2## To find direction, i used sine rule; ##\frac {125}{sin α}##=##\frac {164.2}{sin 135}## ##α=32.56##...

An airfoil section in a wind tunnel has many static ports/holes/taps on its upper and lower surface. These static ports can only read static pressure which acts perpendicularly to the local airfoil surface. In place A are static ports that read a pressure value of relative -100 Pa . This...

Hello, I'm trying to follow the instructions from the book "Aerodynamics of Wind Turbines"-Martin O.L. Hansen, to design a blade, the method it's the BEM accounting for the tip loss (Prandtl) and Glauert corrections, but I can't get it right, for the Cl (lift coefficient) and Cd (drag...

I see there has been threads about Blackbird and "Down Wind Faster Than The Wind" operating principle in general, and I see a good number of people (most?) in those threads seemed to pick up some understanding of how it actually works. So that's a good start and gives me hope. I had never heard...

Hello, I'm wondering if the 1903 Wright Flyer would be able to take off without wind supposing it had a longer takeoff track. Some people here in Brazil claim that there's no proof the Wright Flyer would be able to lift off under its own power. Generally, this revolves around the catapult...

Hi folks, I'm searching for information/procedure and also calculations/equations on how to correctly wind a stator on a (general or DC 3-phase) brushless motor? I.e. how to wind a copper wire X number of times around the stators, and thus get the desired performance/force that is required...

If two cars are driving side by side at the same speed, their relative speed is zero but do they nonetheless perceive a sound Doppler effect from the other car's siren because of the apparent headwind generated by their speed?

I first used differentials to find an equation for the displacement. $$6.0t^2+5.0t=13$$ and using the quadratic formula I got time ##t=1.1## I then got ##V_x## from ##6.0t+5.0=v_x=11.6## and ##V_y## from ##7.0t=v_y=7.7## The I got v from ##V=\sqrt {V_x^2 + Vy^2} ## $$\sqrt {11.6^2 + 7.7^2}...

Is it correct to say: Under the Many Worlds Interpretation: If we rerun the universe repeatedly from the same state S(0), it winds down the same way each time, which is determinism; Under the Copenhagen Interpretation: If we rerun the universe repeatedly from the same state S(0), it may well...

Hi all. I'm new to this forum and to wind turbine technology in general, and I watched one of these one-minute videos explaining why wind turbines pitch their blades but it doesn not make sense to me. Why don't you just get a bigger generator? You'd get more energy for the same blades, same...

I assume that air have ##1 kg/m^3## density. Therefore, using Bernoulli equation, on upside and downside of my test object, there is a differential pressure ##\Delta P##: $$\Delta P=0.5*(v_2^2 - v_1^2)$$ From cases: (a) ##v_1 = 1 m/s## and ##v_2 = 2 m/s##, then ##\Delta P = 1,5 Pa## (b) ##v_1 =...

I solve the following problem, there is a particle of mass ## m_p ## and velocity ## \vec{v}_p ## which collide with sail installed on rail car with mass ## m_c ## resting in the frame of reference associated with it before the collision. The cart is fixed on straight rails for which the vector...

The marker wrote that the answer is 4 and it's because m and v double. I don't understand how m doubles??

I recently read a site dealing with tubular wind chimes. The author give some references that seemed to indicate that the sound we hear is the result of beam bending vibrations after the tube is struck. I'm not so sure about that. It is certainly true that striking the side of an open cylinder...

Let me start be making a small sketch of the problem, shown to the right. If the range of the projectile on a still day ##R = v_{0x}T##, then on the windy day the range becomes ##R+2H = v'_{0x}T = (v_{0x}+v_w) T##. Since the maximum height attained by the projectile ##H =...