1. F

    B Sailboats providing their own wind

    I happened to be watching this cartoon and this one scene seriously bothered me... This... just feels like it wouldn't be a workable solution. Am I wrong? I can't say I perfectly understand how fans or propellers work, but I would imagine that by pushing air or water in one direction, equal...
  2. HotFurnace

    High CFM fan airfoil

    Hi airfoil experts, I brought two high speed fan for magnetron cooling, and upon destroying one due to my mishandling of the stuff, I found out these fan have surprising nice airfoil. See the pictures and you will understand their construction. The rotor part looks just like a normal air flow...
  3. V

    Use only a powerful fan without a compressor?

    Hello & Thanks, Is it possible to use only a powerful fan without a compressor to make very cold air ? Thanks
  4. D

    Electronics Need a small motor and fan to blow air into a 4 inch sphere

    I have a 4 inch sphere with a 22 mm opening. Inside this sphere I will have 3 styrofoam balls 20mm diameter each and 3 styrofoam balls about 5 mm each. I need a wind source to blow wind into the ball through a tube approximately the diameter of a drinking straw, the wind being strong enough to...
  5. A

    Calculating the velocity and pressure profiles across an axial fan

    Hi, This is my first post on the PhysicsFormus I am trying to design an inlet and outlet for an axial fan and calculate velocity and pressure profiles in the duct. See the sketch attached. The ultimate goal is to carry out a CFD study but I was wondering if there is an analytical solution for...
  6. M

    Which fan/pipe combination is the most efficient?

    I'm making a ventilation system with a fan that will blow air through a 1700mm long pipe that has a 45 degree bent in the middle. I should decide on a pipe diameter of 125mm or 160mm. Also I need to choose between 3 different fans that has the following specs from the manufacturer: 120mm fan...
  7. Metahedron

    What torque do I need?

    Good day! How do I calculate how much torque I need in a motor for my project? I must rotate a 100lb propellor, which is 11 ft in diameter, at 1 rpm .
  8. B

    B Adding a nacelle in front or behind the fan?

    Can adding a nacelle in front or behind a standard pedestal fan affect the speed of the air coming in and out? If so, which is more beneficial: an intake nacelle or a nacelle in the front? Using Q=AV, with Q being constant because of the fan blade's max speed, can affecting the area (A) create...
  9. Berg88

    Fan Current to Speed (Percentage)

    Hi All, I have a VFD running supply fans and I currently have two values I can see. One is the VFD actual speed percentage from the VFD. The other is a calculated Fan Speed based off of VFD current. (I control off the calculation). The calculation is (Current^.33)*25.54=%. Does anyone know this...
  10. G

    Calculation of heat created during compression

    1. Homework Statement Hello, I have a task to make a heat balance of the evaporator. To do this, I was told to carry a few smaller energy balances in different parts of the evaporator. One of the things I had to calculate was the heat generated during steam compression. -steam is entering...
  11. Nantes

    I Fans with 3 blades vs. 6 blades (noise, efficiency)?

    I'm Brazilian, and until a few years ago most commercial electric fans sold in the country looked like this: But then one company started making them with 6 blades, claiming it had better wind output and made less noise than the 3-bladed fans (they didn't directly made this claim; it was...
  12. B

    What's the purpose of front white cap that desk fans have?

    Every desk fan has it. What's the purpose of the white cap attached to the front fan grille?
  13. N

    What is more effective -- Current or Voltage?

    I have fan that's 20 V and 14 A. I give it an input of 5V 1A. So my question is............ increasing what will increase the performance of my fan more.... Current or Voltage??
  14. Nantes

    If the air temperature were the same as the human body's...

    Damn title character limits. I just had the weirdest thought while rearranging my computer's case fans. I put my hand in front of one of them and felt a light breeze of air, telling me it was working. This is due to the local cooling produced where the fan's airstream comes in contact with the...
  15. G

    Blocking Back Of Fan Creates Vacuum In Front?

    Hi there, I have recently observed a strange effect regarding a fan and was wondering if someone could explain what's going on. I have a 22cm computer case fan which I am using in a project. For my purposes, I had to partially tape over the back of the fan. I also put a large plastic jar lid...
  16. R

    Hovercraft/Fan/Air compression

    Hi I'm working on a project where I would need to lift about 400 pounds about 1 inch off the ground and keep the momentum in order to manually move it. I thought about using four fans with a skit on each corner facing downward to allow for upward movement, but I'm not sure how much power I would...
  17. B

    Ducted Fan Questions

    Hi guys, I recently completed a fluid dynamics practical at Uni and submitted a report on it, however, I still have some burning questions which I need to be answered. Firstly, the data that we collected shows that as the flow rate in the duct increases, the pressure differential of the fan...
  18. Z

    What gears to use to reduce fan speed from fast moving motor

    hey, I am building a fan, but I need the fan blade to move relatively slow, slow enough to see each panel on the blade. I am expecting to use a gear system with a belt. What gears should I use to active this?
  19. N

    On what does the cfm of fan depend?

    On what does the cfm of fan depend ? how to gain maximum cfm from a 1800 rpm fan ?
  20. A

    Fan Descender Design Project

    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 Could anyone help me with the theory side of its operation. Obviously it uses the fans...
  21. M

    Optimum positioning of fan inside an enclosure

    Hello! I am an electronics engineer and the only time I came across Fluid mechanics was in class 12. I have been stuck for a long time in the finalization of a product. The difficulty is that I need to design a heat-sink, place a fan over it and perform a thermo-fluid simulation of the system...
  22. Z

    Speed of sound in turbulent air?

    If I turn on a standing fan in my room how does the speed of sound change in the fast moving air compared to the still air around it? Would it be relatively faster, slower, or does it depend on the direction in which the fan is blowing?
  23. P

    Ceiling fan blade design

    For the final year project that i am doing, I need to design a high efficiency ceiling fan blade with airfoil section, tapered and also twisting. Can anyone tell me how can i obtain the optimum pitch angle for different section of my ceiling fan blade?