KEVOS® MAKEOS · Mechanics
Flywheel Energy and Speed Fluctuation
How much energy does this flywheel give up between two speeds, and is its rim speed acceptable?
Mass moment of inertia of a disc or ring flywheel, energy released between maximum and minimum speed, coefficient of fluctuation and rim speed.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Flywheel mass | kg | Mass of the rotating disc or rim (weigh it or use the CAD mass). |
| Outer diameter | mm | Outside diameter of the flywheel. |
| Inner diameter of rim (0 = solid disc) | mm | Inside diameter of a ring-shaped rim; 0 for a uniform solid disc. |
| Maximum speed | rpm | Speed before the energy is drawn (e.g. before the press stroke). |
| Minimum speed during the cycle | rpm | Lowest speed allowed during the working stroke. |
| Allowed rim speed | m/s | Rim speed limit from the flywheel maker or your design standard for the material and construction. |
Method and formulas
- J = m(R² + r²) ÷ 2 (solid disc when r = 0).
- ΔE = ½J(ω₁² − ω₂²), ω = 2πn ÷ 60.
- Coefficient of fluctuation Cs = (n₁ − n₂) ÷ mean speed; rim speed = π D n₁ ÷ 60 000.
- Example: a 150 kg, 800 mm solid disc slowing from 600 to 540 rpm gives up 4,500.5 J.
Limitations
- Hub, spokes and shaft inertia are not included unless their mass is part of the entered disc.
- Rim stress depends on construction; the speed limit must come from the maker or a stress analysis.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a press or punch flywheel for one stroke
- Estimate energy stored for a cycle
- Compare rim speed with the maker’s limit
Who it is for
- Design engineers
- Maintenance engineers
- Technicians
What you get
- Mass moment of inertia
- Energy released between the two speeds
- Kinetic energy at maximum speed
- Coefficient of speed fluctuation
- Rim speed
Interpreting the result
- If the released energy is less than the work per stroke, increase inertia or allow a larger speed drop.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3000–3010, 179–186. Topic reference; no source tables or recommended settings are reproduced.
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