EASY/ROCETS is a developmental computer program for mathematical modeling and analysis of dynamic flows of cryogenic fluids in a rocket-engine-testing facility. Heretofore, the numerical simulation of such flows has been accomplished by use of computer codes specific to test-equipment configurations. The complexity of these codes has made it necessary to employ numerical-simulation experts to modify the software for each new configuration. In contrast, EASY/ROCETS is a modular software package that can readily be modified, by choice of modules, for different configurations. Thus, EASY/ROCETS enables engineers who lack advanced numerical-simulation expertise to construct useful mathematical models of test systems, leading to better testing of rocket engines. In so doing, this software also relieves numerical-simulation experts of the burden of day-to-day involvement in modifications of test equipment, enabling them to devote more effort to development of improved component mathematical models that can then be incorporated into the software.

EASY/ROCETS has been constructed from the EASY5x and Rocket Engine Transient Simulator (ROCETS) programs. EASY5x is a commercial software package that provides a graphical user interface to expedite the layout and modification of a system, plotting capabilities that can be utilized for quick display of data, and a numerical-integration engine with several options for analysis. EASY5x also provides representations of basic control system components, which can be used for modeling test-facility control systems.

ROCETS, developed previously under a contract for NASA, is a modular program that provides mathematical-modeling and numerical-simulation capabilities for analysis of flows in rocket engines. A major underlying assumption of ROCETS, and thus of EASY/ROCETS, is that dynamic flows of cryogenic fluids can be approximated satisfactorily by use of lumped-parameter component models. This assumption is valid in most situations encountered in ground testing of rocket engines.

ROCETS includes modules for calculating pressures, mass flow rates, and heat fluxes for flows of compressible and incompressible fluids in pipes, valves, tanks, and heat exchangers. It also includes modules representing turbomachines, properties of constituent fluids (H2, O2, He, and N2), and combustion of H2and O2.

Prior to the development of EASY/ROCETS, ROCETS in its original form was complex enough that a numerical-simulation expert was needed during use to ensure proper connections among modules. Fortunately, ROCETS fits well within the EASY5x software environment. The aforementioned modules have been converted, and new engineering modules are undergoing development.

A license from Boeing Computer Services is required for the use of the EASY5x component of EASY/ROCETS. The user needs either a UNIX computer workstation or a Microsoft Windows NT computer to run EASY/ROCETS. A FORTRAN 77 compiler and a PostScript printer are also required, regardless of the computer system.

This work was done by Randolph F. Follett and Robert P. Taylor of Mississippi State University for Stennis Space Center. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to

Robert L. Palmer
Mississippi State University
PO Box 6156
Mississippi State, MS 39762-5368
(601) 325-3521

Refer to SSC-00044

NASA Tech Briefs Magazine

This article first appeared in the September, 1998 issue of NASA Tech Briefs Magazine.

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