Verification Case 80
PRODUCT: AFT Fathom (with ANS Module)
TITLE: FthVerify80.fth
REFERENCE: Michael R. Lindeburg, P.E., Mechanical Engineering Review Manual, 7th Ed., Professional Publications, Example 5.10, page 5-12.
FLUID: Air
ASSUMPTIONS: N/A
RESULTS:
| Duct Diameter (inches) | Lindeburg | AFT Fathom |
| Duct A-B | 14 | 14 |
| Duct C | 12 | 12 |
| Duct D-E | 10 | 10 |
| Duct F | 8 | 8 |
DISCUSSION:
This duct sizing example used the static regain method to size ducts. The objective of this method is to equalize the pressures along the duct and at each register. This example also placed a maximum velocity limit of 1500 ft/min on the ducts.
To model this in AFT Fathom, two design requirements were created, one with a maximum pressure of 0.4 in H2O std gauge, and the other with a maximum velocity of 1500 ft/min. The velocity design requirement was applied to all ducts and the pressure design requirement was applied to all ducts that were connected between the registers. The first duct attached to the fan was allowed to exceed the maximum pressure design requirement.
A special material model was created of circular ducts from 4 inches to 36 inches with the inner diameter equal to the nominal size.
The automated sizing was discrete with the objective to minimize flow volume.
