Verification Case 18

Problem Statement

PRODUCT: AFT Arrow

MODEL FILE: AroVerify18.ARO

REFERENCE: Mohinder L. Nayyar, Piping Handbook, Seventh Edition, McGraw-Hill, New York, 2000, Page B.398, Example B8.4

GAS: Air

ASSUMPTIONS: 1) Adiabatic flow, 2) Perfect gas

RESULTS:

Parameter	Nayar	AFT Arrow
M1– Mach number at valve	0.243	0.243
P1– Pressure at valve (psia)	168.52	168.61

DISCUSSION:

The problem assumes an unusual inlet boundary condition where the flow rate and the stagnation temperature are known. AFT Arrow uses the static temperature at the inlet because it is typically associated with a flow rate. To match the 120 F stagnation temperature, the inlet static temperature was iterated a few times.

The conditions result in sonic choking at the discharge.

The predictions agree very closely.

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