Fan Definition and 338 Threads

What is the correct type of pressure (static or total) used in the compressibility factor, KP, when calculating fan power? Howden's Fan Engineering book seems to indicate total pressures should be used, but I also have a PDF from Howden that indicates static pressures should be used. Online...

I know how to select a heat sink based on Power dissipation and max junction temp. But how do I relate this to CFM of a fan. How I calculate CFM based on pd and max junction temp?

I have a set up which is basically a small wind tunnel (single rectangular channel) with an axial fan at the inlet. The experiment is testing the effect of various shaped "shrouds" that constrict flow around an inductor to improve the convective cooling. I have heat transfer coefficients and...

http://tehnikservice.net/2008/02/23/fan-controller-by-ic-741/ Guys Can you please illustrate how to connect the components to this layout.. especially the thermistor and R4..thank you !

Hey everybody, I have built a 7' wind tunnel. The test section is 7''x7'' and 24" long. The diffuser opens to 22''. I would like to achieve around 30mph through the test section. I am having trouble finding a fan that can meet that need. I have looked into using an electronic radiator...

Definetly one of the craziest science fiction epics I've seen recently.

Hello forum, I have a ceiling fan with a remote control. The battery dies too quickly. There is only one IC in the little circuit board. I would like to understand where the issue is. Can I do that with a voltmeter? But where would I look? What approach? Where would I measure the voltage to...

Computer brush fan as dc generator Sir, I am using renewable soℝurces like wind for my project.. I need to supply 1.5 to 2 v dc to my amplifier circuit and then to load... I am using computer brush fan as source ...it just gave output upto 2.5v in ideal state when i connected to multimeter...

an ideal electric fan has: a constant supply of 0.49 HP (367.8 watt), 3 motor poles, 8 blades, radius of 36 cm. based on all of that info. how can i find the torque/RPM or both? if you know the answer tell me it with the method to find the torque/RPM. p.s. i just threw in all of the...

Hello everyone. I am working on a VTOL RC craft that I hope will work. I was planning on using a centrifugal fan to accelerate air radially (instead of a squirrel-cage design), and putting 45 degree truncated cones around it to direct it downwards. I wrote a program with many small...

NOOB ALERT - I'm not trying to design a helicopter or a spaceship or something ridiculous, I just want to design a little hovercraft with a computer fan, so don't get all indignant and righteous at me. Anyhoo, I found this Lift equation and tried experimenting with some numbers, just to get a...

hey, so let's say i have an electric fan with something like 2, 1/4 in. blades, 60 rpm, and 10 cm diameter and i want to attach it to an object and turn it on so it would fly (like a quadrotor) before i try, i want to know if it is possible by knowing how much counter force can it make on the...

Why air flow created by ceiling fan (which rotates counter clockwise (seen from beneath ceilling) ) goes downward?

A little while ago I asked: why does wind feel cold. The molecules are moving faster so it should feel hot. The answer I got was that it increases the evaporation rate of water from your skin. Less water makes you feel cool, I think. Maybe there were some other reasons which I've forgotten...

If room A is connected to the outside with a window and room A has a fan on; Would the air would try to move out from room A to the outside because there is a higher pressure inside the room? in concept

I made this video a while back: The black box is a bitcoin miner (irrelevant) with a fan that blows upwards just underneath the holes. I was trying to make the piece of paper float. I think this should be possible since the air velocity is higher on the outsides of the fan than in the...

I have a question about fans and airflow, specifically related to processor cooling. I have a large heatpipe/radiator on my processor which came with one fan installed that blows air across the fins (a push fan). The assembly is set up to be able to add a second fan on the opposite side to...

Does a ceiling fan consume more electicity at higher speeds or is the same at all speeds?

if i had a circular fan with 8 blades and the diameter of 1 foot, how fast would it have to spin to push 125 Lbs of air? if the angle of the blades would matter, it would be around 45° if more specifications are needed, please let me know

Hello. I'm trying to control the speed of a fan (12V cpu cooler) with PWM (555 + MOSFET). Should be quite straightforward, but i noticed that the speed of the fan does not seem to always change in the same way the duty cycle does. With an optical RPM meter I'm seeing that the lowest RPM...

Hello, Here are the known's of a chassis: Inlet open area = 17 inches^2 Outlet open area = 30 inches^2 Internal Fans = 270 cfm (3 fans @ 90 cfm each) What is the CFM through the system and what's the equations used to figure this out? I assume that if we had a very small inlet or...

Hey guys! I would like to know what would happen to a fan that is rotating inside a system without air. Imagine you take all the air off the system and after that you put the fan rotating. The only opposite force acting to make it stop would be the air resistance, but as no air, what would...

If I know fan specifications like the size, CFM etc. How can I calculate the pressure thrust or negative pressure it creates. I am using a fan in an opening of the cabinet that pushes air outside the cabinet. And I need to know how much pressure drop it will cause on the suction side. It will...

If I had a fan sitting in a small duct, and used several different sized orifice plates to create different restrictions, how would I find the fan curve? I run the fan at the same RPM each test. The problem I run into is using the equation for orifice flow that relates pressure drop, area...

amazon.com/gp/product/B000XTFYSQ/ref=oh_details_o01_s00_i00So I bought this fan. My modem zoom 5341 kept overheating. So I stuck this in there, and soldered it to the 6v incoming. Now, it's a bit too loud. I've never run it off 5v to see how loud it would be, but I imagine it would still be a...

Homework Statement For decades, people have dreamed of cars that can fly. You are part of a team which hopes to build the worldʼs first commercial flying car. Your proposed design has four fans, each of radius 50cm. Each fan sucks in air from above the car and blows it downwards. The...

Homework Statement You are part of a team which hopes to build the worlds first flying car. Your proposed design has four fans each of radius 50cm. Each fan sucks in air from above the car and blows it downwards.The downward flow of air can be apporximated as a column of radius equal that of...

Excuse my lack of knowledge on PWM and fans, but can a fan configured with 4 wires (power, ground, tach. signal, and PWM input) be run off of a DC power supply without using the PWM to control its speed? As in, not using the PWM lead and just hooking up power/ground and controlling fan speed...

1.The motors driving the fans of a large cooling tower must be represented in a dynamic simulation of a power plant auxiliary system. Each fan can be described as follows: Fan diameter = 4.5 meter No of blades/fan = 6 Fan RPM = 90 The fan blades have a tapering cross section. The fan...

Hi, I would really like some insight here, I don't know what I'm doing! also, sorry if i get the terms wrong and miss the obvious, this isn't my field. I will try to keep this short: I think that if you have a solid object, with a Heating element in the centre, and the surface in ambient...

I don't know if this is the right place to ask this, but I'll give it a try. I have a PC with a rather noisy fan which I'd like to replace so I got a new one with lower RPM and of better quality. However, there is one little problem: The PC won't boot with the new fan. I contacted the...

Evening gents, I am somewhat of a novice with electronics, but nonetheless am working on a temp. controlled computer fan but I've run into some trouble and need some help! My basic layout is a thermistor implemented as a voltage divider (with a resistor of course) which feeds into an amp...

Hi, Might sound like a homework problem but since it isn't I posted it here. I currently live in a small 22m^2 student apartment. Heating is included in the rent, in the shape of a basic water radiator located below the window towards the wall (dont worry, there is nothing standing towards...

Homework Statement Determine the power of a windmill using constants where appropriate.Homework Equations P = Fv K = (1/2)mv2The Attempt at a Solution Dynamics Method P = Fv In time Δt, Δm amount of wind passes through the windmill, at speed of v. Δp = vΔm = v(AρΔx) Dividing both sides...

I am doing a project where in a pedestal fan is alternatively powered using a flywheel. The flywheel is brought to some initial angular velocity by the electric motor. Now, if the power goes off, the fan blades would be coupled to the flywheel and it continues to rotate for the next 10 minutes...

angular acceleration of a fan! Homework Statement An electric fan is turned off, and its angular velocity decreases uniformly from 500 rev/min to 200 rm rev/min in 4.00 s. Find the angular acceleration in rev/s and the number of revolutions made by the motor in the 4.00 interval...

fellow engineers, hi I'm totally new here so hello everyone. I'm a mechanical HVAC design engineer and I have a question about fan power and fan heat gain/generation. My main concern is the temperature rise in the air passing through the fan. I've been researching in books and on the...

What will fail if the aluminium impeller rotating at 7500 rpm and powered by 355 kw motor strikes against the stationary 10 mm thick ms plate welded at both the ends having length of 350 and width 200 mm and impeller blade is 12 mm thick. I am confused in first glance we think that blade will...

If I have a typical Fan with a given CFM or even the outside diameter of the blade can I find the exIting temperature? Is there a formula out there to determine the exit temp. Assumptions: The fan is located in the middle of a room so we are not mixing in different temperatures. Given...

Hello, I and my team are making a project in which we have to build a fan which ,when run , will push air down and with some considerable pressure. The Fan will be positioned horizontally. What should be the Blade Profile for such a fan ?? I do not think a lift wing blade profile could be...

Hi guys! This is the third (and in my opinion, the most whimsical) chapter in a series of short stories I wrote about mathematics and physics; I hope you guys like it. Helpful comments or suggestions are welcome. Thanks...

Alright so I have been bored this summer so decided to take apart my electronics such as my Xbox and AV receiver. I installed a nice 12vdc computer fan on the side of my Xbox so I moved onto my AV receiver and then ran into some problems. My current set up consists of: 2x - 12vdc computer...

I own a copy of Griffith's Quantum Mechanics and I like how it is written very much but while skimming through Griffith's Particle book I saw a reference that said "at the level of Park" and I decided to investigate. I started to read through it and the text is structured the way most books...

Hello everyone, I am trying to simulate Earth tubes for pre-cooling using the EnergyPlus software. Basically a fan will be used to circulate ambient air through an underground horizontal pipe. The software requires an input field of "Fan Pressure Rise" which I am guessing is the pressure...

Hi, I wanted to create my own computer fan control and bought a 100ohm potentiometer. I have hooked the pot as shown in the picture except that it is in the yellow wire (+12V) and not the red one (+5V) , black is ground. The fan will start at full speed and doesn't change one bit if I...

Homework Statement A ceiling fan is turning at a rate of 100 revolutions per minute. A spiders is clinging to a blade of the fan. If the spider experiences a centripetal acceleration greater than 0.3g, it will lose its grip on the blad and be flung off. How far from the centre of the fan can...

An electric ceiling fan with blades of diameter 0.720 m is rotating about a fixed axis with an initial angular velocity of 0.240 rev/s. The angular acceleration is 0.899 rev/s^2. C- What is the tangential speed of a point on the tip of the blade at time t = 0.201 s? D- What is the magnitude of...

hello, I am supposed to give a short (20-30 mins) lecture to some very smart 2nd year math majors, and i thought about finding an intersting physics topic. my first idea was special relativity, or more specificly deriving E=MC^2 from einsteins assumptions about light's behevior, but in the...

I have a tiny fan installed in the lid of my aquarium (it's actually a CPU fan). It moves air from the air space over the water surface below the light. It's purpose is several-fold: 1] supply oxygen to the air-water interface, remove CO2 2] remove excess moisture 3] remove waste heat due to...

Right now (1600 IST, 3 march) I am sitting on my chair. When I look at the fan at a specific angle (about 75 deg) I can see a blue colour at one edge of the wings and yellow colour at the opposite edge of the same wing. In my room there is one source of natural light and one white artificial...