Computer program solves time-dependent energy and state equations for gas reservoirs, using the solutions of conductor conservation equations as mass and energy rate changes to reservoirs

Leblanc, L. P.

English

NASA Technical Reports Server

October 1975	 B75-10234 
NASA TECH BRIEF 
Lyndon B. Johnson Space Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Multiple-Compartment Venting Program 
The problem: 
In a system of gas reservoirs connected by orifices 
and pipes, it is important to be able to predict the 
pressure history of various reservoirs, the pressure 
differential between reservoirs, and the mass flow rate 
through the conductors connecting these reservoirs. 
The solution: 
The pressure in a gas reservoir is dependent on the 
state properties of the gas and the net mass rate 
entering or leaving the compartment. The mass flux 
leaving or entering a reservoir is a function of the type 
and size of the conductor connected to the reservoir 
and the pressure differential across the conductor. 
The change in mass and pressure within the reservoir 
also results in a change in the state properties of 
density and temperature. A computer program has 
been written which solves the time-dependent venting 
equations for an arbitrary number of compartments 
interconnected by any number of orifices and/or 
pipes. 
How it's done: 
This computer program solves the time-dependent 
energy and state equations for the gas reservoirs, 
using the solutions of the conductor conservation 
equations as mass and energy rate changes to the 
reservoirs. However, for the solutions of the conductor
conservation equations, the reservoir conditions are 
used as boundary conditions. This coupling of the 
boundary conditions and the reservoir/conductor 
conditions is handled within the program by analyzing 
each conductor separately, and assuming quiescent 
conditions in the connected reservoirs, and by 
calculating a steady-state flow condition in the 
conductor. The assumption of the quiescent condi-
tions within the reservoir is realistic whenever small 
time-integration steps are taken. Thus, for each 
conductor analyzed, a free system of two reservoirs 
and the conductor is used, and the appropriate set of 
equations is applied. 
Notes: 
1. This program was written in FORTRAN IV for the 
IBM 360-series computers. 
2. Inquiries concerning this program should be 
directed to: 
COSMIC 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30601 
Reference: MSC-19428 
Source: L. P. LeBlanc of
Rockwell International Corp. 
(MSC-19428) 
Categories: 06 (Mechanics) 
09 (Mathematics and 
Information Sciences) 
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Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
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Multiple-compartment venting program

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