Flywheel Definition and 264 Threads

A flywheel is a mechanical device specifically designed to use the conservation of angular momentum so as to efficiently store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, if we assume the flywheel's moment of inertia to be constant (i.e., a flywheel with fixed mass and second moment of area revolving about some fixed axis) then the stored (rotational) energy is directly associated with the square of its rotational speed.
Since a flywheel serves to store mechanical energy for later use, it is natural to consider it as a kinetic energy analogue of an electrical inductor. Once suitably abstracted, this shared principle of energy storage is described in the generalized concept of an accumulator. As with other types of accumulators, a flywheel inherently smoothes sufficiently small deviations in the power output of a system, thereby effectively playing the role of a low-pass filter with respect to the mechanical velocity (angular, or otherwise) of the system. More precisely, a flywheel's stored energy will donate a surge in power output upon a drop in power input and will conversely absorb any excess power input (system-generated power) in the form of rotational energy.
Common uses of a flywheel include:

Smoothing the power output of an energy source. For example, flywheels are used in reciprocating engines because the active torque from the individual pistons is intermittent.
Energy storage systems
Delivering energy at rates beyond the ability of an energy source. This is achieved by collecting energy in a flywheel over time and then releasing it quickly, at rates that exceed the abilities of the energy source.
Controlling the orientation of a mechanical system, gyroscope and reaction wheelFlywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a maximum revolution rate of a few thousand RPM. High energy density flywheels can be made of carbon fiber composites and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM (1 kHz).Carbon-composite flywheel batteries have recently been manufactured and are proving to be viable in real-world tests on mainstream cars. Additionally, their disposal is more eco-friendly than traditional lithium ion batteries.

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  1. M

    Spinning Flywheel in Suitcase: Understanding Torque and Precession

    Homework Statement A famous practical joke makes use of a suitcase, inside which is mounted a flywheel which is rapidly spinning about a horizontal axis. Describe what a porter experiences when he tries to turn the corner carrying the suitcase. If the flywheel has a mass of 5 kg, a radius of...
  2. L

    How Do You Calculate Torque in a Gearbox-Flywheel System?

    Homework Statement Gearbox coupled to a flywheel. The gearbox I 92% efficient and the output shaft rotates at 5 x the speed of the input. Flywheel mass is 50kg, 0.75 m radius and is to accelerate from 0 to 300 rpm in 60 seconds. Calculate Input torque and holding torque (value and...
  3. J

    Flywheel inside a spaceship experiment

    Given the above setup in this image, there is a fast spinning massive flywheel inside a spaceship. The flywheel is only connected via a lock to a spring. What would happen if the retractable steel wall moves towards the steel ball (purple) which is connected to the fly wheel, so the steel...
  4. karush

    MHB How Fast Does a Flywheel Spin at 7 Radians per Second?

    A flywheel with a $15cm$ diameter is rotating at a rate of $\displaystyle\frac{7 rad}{s}$ What is the linear speed of a point on the rim, in $\displaystyle\frac{cm}{min} $. $s=r\theta$ so $7.5(7) = 152$cm then $\displaystyle v=\frac{s}{t}=\frac{152cm}{s}\cdot\frac{60s}{min}=\frac{1320cm}{min}$...
  5. B

    Frictional talk - mass suspended from a flywheel

    frictional talk -- mass suspended from a flywheel Homework Statement a mass of 0.5kg is suspended from a flywheel. if the mass is released from rest and falls a distance of 0.5m in 1.5sec calculate the frictional torque. mass of wheel = 3kg Radius= 0.3m Radius of gyration = 0.212mHomework...
  6. M

    Controlling torque output from a flywheel

    Question Is there a component that controls the torque output from a flywheel so that its output is constant? Context: Parts: 1) An engage/disengage switch 2) A cable reel 3) A flywheel 4) A mechanism to control the torque output from the flywheel. Process When the switch is...
  7. P

    Frictional Torque of a Flywheel

    1. A mass of 0.5 kg suspended from a flywheel, if the mass is released from rest and falls a distance of .5m in 1.5s calculate a) the linear acceleration of the mass b) the angular acceleration of the wheel c) the tension in the rope d) the frictional torque, resisting motion mass of wheel...
  8. B

    How Do You Calculate the Power Produced by a Pendulum-Driven Flywheel?

    Hi, a pendulum drives a flywheel using a over run clutch so the flywheel will only spin in one direction. The length of the pendulum is 2.5 meters and the bob weight is 25 kilograms. It is a rigid pendulum. The flywheel diameter is 4 meters. 4.5 kilogram weights are placed at 60 degree...
  9. A

    Torque required to overcome inertia and friction on a flywheel

    ∂hi all. I sort of understand this question but not fully so here it goes: A shaft carrying a flywheel of diameter 565mm and mass 210 kg is required to run at a speed of 710 rev/min. If the working speed is to be reached in 16 seconds from rest and the coefficient of friction between shaft and...
  10. M

    Input Power against time graph - Flywheel rest to 300rpm

    Hello, Homework Statement A gearbox and flywheel are as shown in FIGURE 4. The output shaft rotates in the opposite direction to the input shaft at 5 times its speed. The gearbox has an efficiency of 92%. If the flywheel is solid, has a mass of 50 kg, a diameter of 1.5 m and is to...
  11. S

    Angular Momentum and Flywheel Energy problem?

    Hi guys, basically i have a few questions with regards to Prof Walter Lewin's videos. Firstly, this is the video of him explaining the flywheel concept with energy involved: My question is, why does a flywheel actually spin when the car goes downwards? how does the flywheel actually converts...
  12. R

    What happens to energy in a gyro vs. flywheel problem?

    I have a problem which got me thinking, but I'm unable to solve to my satisfaction. The problem involves a gyro attached to a platform which in turn is attached to a flywheel. (See image below) The constraints are as follow: The platform & flywheel are solidly attached to each other and...
  13. mesa

    Basic gyroscope question about replacing the flywheel with balanced masses

    Would a pair of balanced weights connected rigidly about the spin axis operate in the same manner as a standard gyroscope with a flywheel?
  14. B

    Flywheel design. Inertia dyno for 745 KW engine.

    Hello again, I am currently designing a flywheel for a 745 KW engine inertia dyno. Basically my design requirements are so: Max RPM: 530 RPM (=55.5 rad/s) Flywheel Diameter: 1.7 meters Time needed to accelerate: 60 second (to max rpm) I need help determining the mass of the...
  15. M

    Determining optimum flywheel dimensions

    Hello all, I am currently doing a design project on gyroscopes. My question concerns the flywheel design, specifically trying to determine the dimensions of a flanged free-spinning flywheel to maximize the moment of inertia while trying to minimize the mass, given certain design constraints...
  16. O

    Flywheel RPM when Power Returns: 477.628992424 rad/s

    At what rate is the flywheel spinning when the power comes back on? A high-speed flywheel in a motor is spinning at 450rpm when a power failure suddenly occurs. The flywheel has mass 44.0kg and diameter 77.0cm. The power is off for 32.0s and during this time the flywheel slows due to friction in...
  17. J

    Flywheel Inertia: Fixed Internal Quantity?

    Basically, for a standard flywheel (heavy Metal disc), Is its moment of inertia a fixed internal quantity for that flywheel which doesn't change dependent on angular velocity etc?
  18. J

    Conservation of energy flywheel experiment

    Hi Ive recently carried out an experiment where different masses are hung from a string and then dropped from the same height. The other end of the string is wrapped around the axle of a flywheel and when the mass hits the ground, the time for ten revolutions of the flywheel is calculated to...
  19. S

    Solve Flywheel & Torque Homework: Find Torque

    Homework Statement Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.5 m diameter and a mass of 270 kg. Its maximum angular velocity...
  20. W

    I`m making a flywheel and with the math

    First off thanks in advance for any help given here. Hope you don`t mind bullet points. Makes it easy for me. I`m building a type of flywheel that consist of: 1) A single rod 2 ft across. Axel in the middle. 2) A 2 lb weight on both ends of the arm. 3) Rod weight 1 lb. 4)...
  21. C

    Understanding the Difference Between Energy and Power in Flywheel Calculations

    I've got a flywheel spinning at 850RPM. It weighs 112,34g and has a radius of 38mm. I want to calculate the Kinetic energy (Ek) it has given in Wh (watt per hour).Angular speed: ω = n*2pi()/60 = 850*2pi()/60 = 89,011 rad/s Moment of inertia: I = 0,5*m*r2 = 0,5*0,11234Kg*0,038m^2 = 0,00008110948...
  22. B

    Flywheel Help: Which Will Keep Turning Longest?

    I have 3 x Flywheels of equal dimensions but different weight eg a.400lbs b.800lbs c.2000lbs,which one will keep turning the longest? Or is there no difference?
  23. U

    Help with Flywheel design

    I am designing a flywheel for my own system. I don't know what are the input I should consider to design my flywheel and need to find what is mass & speed of flywheel should I use for my system to avoid fluctuation and uniform motion. I have attached the system picture and I have mention the...
  24. T

    Wind resistance on a rapidly rotating flywheel

    I am simulating a rapidly rotating (horizontal axis, if that makes a difference) flywheel. The software isn't too sophisticated w.r.t. wind resistance, unfortunately, and seems to use the diameter of the rotating body as one of the main parameters, in addition to the velocity of the rotating...
  25. E

    Finding High-RPM Induction Motor for Flywheel System

    Hi Me and my friend is starting a project to building a flywheel system with aim for energy storage. This is a small budget experiment to see how long flywheel can hold energy with our design. One problem we face is finding a suitable motor, we plan to use induction motor to avoid eddy...
  26. R

    Flywheel problem with limited data? Is it possible?

    A solid circular flywheel around which a string is wrapped. At the end of the string is a 2 kg mass. If the mass is dropped, the drum will rotate. After the mass has fallen h metres, it has a velocity of v m/s and the wheel has a rotational velocity of ω rad/s The flywheel radius is 120...
  27. M

    What Are the Initial Angular Velocity and Angular Acceleration of the Flywheel?

    A flywheel makes 80 radians in 4 second and is rotating with constant angular acceleration during this time . It makes 60 radians in next 4 second with constant angular velocity . Find initial angular velocity and the angular acceleration ? my answer is form this equation Q= w0t +...
  28. B

    Flywheel Energy Storage: Powering Common Products with Kinetic Energy

    HI All!, I'm a thesis student in Industrial Design and need some physics help! My thesis project is to make a system that stores energy in the form of kinetic energy in a flywheel to power common products. This system would be plugged in all the time and would begin working immediately after...
  29. R

    Flywheel generators in vehicles.

    Is it that, flywheel electric generators are not used in vehicles because? The momentum of the wheel will tend to have the vehicle continue in a straight line rather than turning a corner with that vehicle? If so, what would we expect if the flywheels' orientation changes with the direction of...
  30. J

    How Weight of Flywheel Changes in a Gravity Well

    A spinning flywheel is lowered into a gravity well using an elevator. Energy flows from the flywheel into the elevator motor (which functions as a generator in this case). The energy is red shifted by gravity, and equivalently by centrifugal force. To be more specific the force part of...
  31. L

    Flywheel Size for Small vs Large Engines - Which is Best?

    do we need a massive flywheel for a small engine or a large engine? i blive that the lager engine will require a smaller flywheel. and for a high speed engine i think we are going to need a larger flywheel to minimize its speed, otherwise wouldn't the care be out of control.
  32. L

    Governor vs Flywheel: What's the Difference?

    what is the difference between flywheel and governor in a car. they are both used to minimize speed fluctuations but what is there basic difference?
  33. C

    How Do You Calculate the Kinetic Energy of a Flywheel?

    Homework Statement Q: A flywheel of moment of inertia 0.32kg/m^2 is rotated steadily at 120rad/s by a 50W electric motor. Find the kinetic energy of the flywheel.Homework Equations What is the best way to work this out? Am I using the right equations? Can I simply substitute the angular...
  34. T

    Finding Angular Velocity from Known Angular Acceleration

    Homework Statement If we only know the force Fr, Find the angular velocity of the flywheel. Homework Equations The Attempt at a Solution in the pulleys F=F1=F2=F3 Fr=(F Sin β)/sin (β/2)=2F cos (β/2) F = (2 cos (β/2))/Fr so now for the flywheel I=1/2 MR2 ...
  35. T

    Flywheel effect on torque fluctuation of an IC engine

    How does a flywheel reduce torque fluctuations in a IC engine? Of course the more inertia you have, the less rotational speed fluctuation you get. But how does more inertia lead to less 'torque' fluctuation?
  36. S

    Tangential and radial accelereations of a flywheel

    I found this question in a book and I am trying to answer it by myself. Here's the question and my solution. A flywheel rotates with constant angular velocity. Does a point on its rim have a tangential acceleration? A radial acceleration? Are these accelerations constant in magnitude? In...
  37. J

    KERS System with Flywheel and IVT

    I'm working with a kinetic energy KERS (Kinetic Energy Recovery and Storage) system that use a flywheel coupled via an IVT (Infinitely Variable Transmission) to a vehicle. The vehicle load is Ib and Lb is known at the driveshaft. Considering only the inertial loads (I.E. ignoring all friction...
  38. A

    Mechanical press - energy of flywheel

    Goodmorning, I know that the mechanical power press constructors give: 1) the diagram of permitted work depending on used number of slide single stroke per minute; 2) the diagram of eccentric loads on the slide (ellipsis graph). But I don't know how they can do these ones. For question...
  39. J

    Object moving radially outward on Rotating Flywheel

    Hello. This has been bothering me. A point mass is on a rotating flywheel that has a constant initial angular velocity, ω0. The object (point mass), initially at some distance r0 from the axis of rotation, now moves out to a further distance rf, and then stops. Say the wheel has a moment of...
  40. D

    Finding moment of inertia of a flywheel using rotations, with friction.

    ive recently done a experiment which involved a flywheel which was rotated by the force of gravity on a mass which was wrapped around the flywheel axis. I have tried to calculate functions which will predict the behaviour as well as get the moment on inertia of the flywheel via torques of...
  41. R

    Calculating Acceleration of a Flywheel Driven by a Pulley System

    A flywheel is driven by a pulley system. friction in the system exerts a braking force of 2Nm. The moment of inertia is 400kgm2. The forces in the pulley belt are 120N on the tight side and 80N on the slack side. Pulley diameter is 0.2m Calculate the acceleration of the wheel. the pulley...
  42. D

    Calculating omega as a function of time for a flywheel

    hiya all, I've done a experiment which was hanging a mass from a light string wrapped around the axis of a flywheel. The mass was released and the flywheel began to rotate. during calculations I've found out it would be great to have ω as a function of time and I've been stuck about how to...
  43. H

    How Do You Calculate v and w for Flywheel Inertia?

    I have managed to rearrange an equation give to me to make I (moment of inertia) the subject. I am now having problems working out the values for parts of it. I = moment of inertia m = mass g = gravity h = height v = translational speed of the mass falling Tf = work done against...
  44. S

    Inertia of a flywheel, with a mass attached in a cord.

    Homework Statement Hi :) So we've been given an exercize, where we have to calculate the inertia of a rotating flywheel in three different methods. The setup can been seen below. First by measuring and calculating the diameter, mass, radius, volume etc. Worked out just fine. The...
  45. QuarkCharmer

    Flywheel storing kinetic energy

    Homework Statement There is a 2.30 m diameter flywheel, with a mass of 75.0 kg. For safety/structural (or whatever) reasons, the acceleration at a point on it's rim cannot exceed 3430 m/s^2. What is the max KE that can be stored in the flywheel? Homework Equations KE = \frac{1}{2}Iω^{2} I =...
  46. X

    Analyzing Torque and Angular Acceleration in a Flywheel Problem

    1. Homework Statement A flywheel in the form of a uniform disk (I = ½ MR2) 5.0 ft in diameter, weighs 650 lb. What will be its angular acceleration if a net force of 225 ft-lb acts it upon? If the disk is rotating at 1200 rev/min, what torque is required to stop it in 30 minutes? Homework...
  47. Y

    Flywheel Inertia Design for Piston Engine

    Homework Statement A flywheel is to be designed for a single cylinder double acting piston engine. The crankshaft has a mean speed of 1000rpm and a maximum and minimum rpm of 0.3% above and below this respectively. The torque deliverd to the crankshaft is 100 Nm from top dead centre to...
  48. L

    Flywheel moment of inertia(torque)

    An electric motor turns a flywheel through a drive belt that joins a pulley on the motor and a pulley that is rigidly attached to the flywheel, as shown in Figure P10.39. The flywheel is a solid disk with a mass of 80.0 kg and a diameter of 1.25 m. It turns on a frictionless axle. Its pulley...
  49. N

    What does the 97% storage efficiency of a flywheel represent?

    In my exploration of energy storage options i came across a statistic several times that given a vacuum and magnetic bearings, a flywheel can achieve 97% storage efficiency. Whether its true or not, what does 97% represent? Does it imply that the energy will hold regardless of time and its a...
  50. B

    What type of flywheel would be best for improving performance in a truck?

    Hello, I have a question on a flywheel. I have been racking my brain over this for months, and still no good answer.I i have a 4 wheel drive truck, that is 4,500.lb. 100hp at 4,000.rpm, and 200lb. ft at 2,000.rpm, at the flywheel. The vehical drives at 50mph at 2,500.rpm. with a 1 to 1 final...
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