Rotating%20Disk%20Viscometer

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Rotating Disk Viscometer

• Problem 1.55
• Jillann Walker
• 12.12.06

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Abstract
Given the rotating disk viscometer, determine the
viscosity of the oil, and also determine the
overall uncertainty in viscosity if each
parameter ( M, R, h, f) is /- 1percent.
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Diagram
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Known Values

• R 5cm
• h 1mm
• f 900rpm
• t 0.537 Nm

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Solve For

• V Tangential Velocity
• -Used in viscosity formula
• µ Viscosity

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Assumptions

• Closed system
• Density is not relevant
• Shear stress is consistent throughout
• Velocity is linear

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Equations

• Viscosity
• Tangential Velocity

Note V Tangential Velocity
Note r radius of disk
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Solution

2 x 3.14 x 0.05m x 15
4.71239
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Explanation

• Shear takes place at the surface of the disk over
  the area.
• Higher velocity require lower viscosity
• Higher clearance requires higher viscosity
• 1 percent uncertainty
• Largest uncertainty range at 1 on the top and -1
  on the bottom of the plate
• This is not a 2 difference

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Biomedical Relation

• Shoulder joint or ankle joint.
• Refer to a ball and socket
• The joint fitting will contain liquid of some
  sort and depending on the resistance needed to
  rotate the joint, will determine the viscosity of
  the liquid.

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Questions?