Verification Case 12
PRODUCT: AFT Arrow
MODEL FILE: AroVerify12.ARO
REFERENCE: Michel A. Saad, Compressible Fluid Flow, 2nd Edition, Prentice-Hall, Englewood Cliffs, NJ, 1993, Pages 226-227, example 5.5
GAS: Air
ASSUMPTIONS: 1) Adiabatic, 2) Perfect gas
RESULTS:
| Parameter | Saad | AFT Arrow |
| Mass flow rate when choked (kg/s) | 2.11 | 2.10 |
| M1 – Mach number at inlet | 0.603 | 0.603 |
| P1– Static pressure at inlet (MPa) | 2.106 | 2.114 |
| T1– Static temperature at inlet (deg. K) | 427.8 | 429.5 |
| P2,choke– Static back pressure for choking (MPa) | 1.203 | 1.220 |
DISCUSSION:
All results agree closely. The AFT Arrow static pressure below which choking occurs is the pipe exit static pressure.
Note that the friction factor in Saad is the Fanning friction factor. To obtain the Darcy-Weisbach friction factor used in AFT Arrow, multiply the Fanning friction factor by 4.
