Verification Case 1
PRODUCT: AFT Arrow
MODEL FILE: AroVerify1.ARO
REFERENCE: John D. Anderson, Modern Compressible Flow, 1982, McGraw-Hill, page 76, example 3.4
GAS: Air
ASSUMPTIONS: 1) Adiabatic, 2) Perfect gas
RESULTS:
| Parameter | Anderson | AFT Arrow |
| M2 – Mach number at exit | 0.475 | 0.473 |
| P2– Static pressure at exit (atm) | 0.624 | 0.624 |
| T2– Static temperature at exit (deg. K) | 265.8 | 265.9 |
| Po2– Stagnation pressure at exit (atm) | 0.728 | 0.728 |
DISCUSSION:
As specified, inlet conditions are known and outlet conditions need to be determined. With the known inlet conditions, an implied mass flow rate exists. To pose the problem in AFT Arrow terms, a few simple calculations are needed to obtain the mass flow rate. Once obtained, it is applied as a flow demand at the exit.
The problem states that the inlet Mach number is 0.3, P1 = 1 atm, T1 = 273 K. From the ideal gas law, density, sonic speed and mass flow rate are:
Note that the friction factor in Anderson is the Fanning friction factor. To obtain the Darcy-Weisbach friction factor used in AFT Arrow, multiply the Fanning friction factor by 4.
