Design of Shaft Diameter for a rotating Drum

  • #1
Hi All,

I am designing a hollow rotating drum equipment which will be filled with specialized media for wastewater purification. I need help to design the shaft diameter for the entire assembly. The Drum will be hollow with a diameter of 1.77 meter and length of 2.5 filled with some kind of material in it. It will be submerged in the liquid at 50% level and will be rotating at 2.7 RPM with peripheral velocity of 15 m/min. The total weight of the drum would be round 1555 kgs. The length of shaft will be 5 meter and mounted with bearing on one end and drive unit on other end. Kindly let me know what can be the shaft diameter and how can We calculate it?
  • #2
You have not specified if the shaft is horizontal.
You have not specified the torque required to rotate the drum and contents.

The shaft must be of sufficient diameter that it:
1. Is able to transfer the torque required to start and turn the drum.
2. Does not sag and misalign the support or drive bearing.
3. Does not suffer fatigue failure due to continuous reversal of load during rotation.

In that situation I would consider using a tube for the full length shaft. Only at the support bearings need the diameter be reduced to a solid stub axle.

Why must there be a long single shaft. With a drum of that size it might be better to fit a stub axle at each end of the drum and employ an indirect drive with a belt to the surface of the drum. That reduces the gearing needed on the drive unit. Being half submerged has implications to the location of the drive.

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