Verification Case 27

PRODUCT: AFT Fathom

REFERENCE: Michael R. Lindeburg, P.E., Mechanical Engineering Review Manual, 7th Ed., Professional Publications, Page 5-6, Example 5.6

FLUID: Air

ASSUMPTIONS: Air is at 70 deg. F, inlet pressure is 5 inches of water, gauge, wall roughness is 0.00538 inches

RESULTS:

Parameter	Lindenburg	AFT Fathom
Velocity (feet/min)	2200	2170
Pressure loss(in. water per 100 feet)	0.5	0.4867

DISCUSSION:

The reference solves the problem using a chart. No roughness data for the duct is given. Using the chart on page 5-7 of the reference, a representative roughness was determined as follows: for a 12 inch duct at 3000 feet/min, the pressure drop is 1 inch of water per 100 feet. This information was entered into the AFT Pipe Sizing Utility (PSU, part of the Engineering Utility Suite) to obtain an effective duct roughness. A value of 0.00538 inches was obtained, and this was used in AFT Fathom. Results from PSU are given below.

Slight differences in predictions above result from the reference's round-off errors and reading the solution from a chart.

PSU Results
- Friction Factor = 0.01788
- Epsilon = 0.00538 inches
- Hazen-Williams Factor = 110.390
Input Parameters
- Delta Pressure = 1.000 in. H2O std.
  - Velocity = 3000 feet/min
  - Vol. Flow Rate = 39.270 ft3/sec
  - Mass Flow Rate = 2.941 lbm/sec
  - Reynolds Number = 306548
Geometry: Cylindrical Pipe
- Diameter = 12 inches
- Area = 0.78540 ft2
- Wetted Perimeter = 37.699 inches
- Length = 100 feet
Fluid = Air @ 1 atm (vapor)
- Temperature = 70 deg. F
- Density = 0.0749 lbm/ft3
- Dynamic Viscosity = 0.04398 lbm/hr-ft

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