A library of computer subprograms for use in air-breathing propulsion analysis computer programs

Modern aircraft and missiles frequently operate in the high supersonic speed range where real gas effects are observed and the classical gas dynamic relations based upon the thermally and calorically perfect gas assumption are inadequate. Historically, the classical gas dynamics texts such as Shapiro and Liepmann and Roshko have been predicated upon the perfect gas assumption. Current engineering applications such as air-breathing propulsion analysis and test data reduction, however, require the application of computational algorithms that account for real gas effects. Consequently, many modern gas dynamics texts are now addressing real gas effects. With the computational facilities available to analysis and test engineers, it is practicable to incorporate real gas effects in engineering analysis and test data reduction computer codes.

State-of-the-art computer codes for air-breathing propulsion analysis and test data reduction are written on a modular basis. Required modules for such codes include sets of computer subprograms for determination of the thermodynamic and transport properties of the working fluids, atmospheric models, and gas dynamic processes such as isentropic expansions, compressions, normal, and oblique shocks. Although many chemical equilibrium codes are readily available to the propulsion community, the majority are so general in nature as to be too large and cumbersome to be included in calling codes as subprograms when computer resource requirements must be minimized. Further, none of the readily available codes include real gas effects such as intermolecular forces (instead, the perfect gas equation of state is incorporated). Similarly, few existing codes provide for determination of transport properties.

Although the subprograms comprising this thesis were originally developed for use in flight vehicle air-breathing propulsion test data reduction codes at Arnold Engineering Development Center, they are general in nature and can easily be incorporated into fluid dynamic (Navier-Stokes) and gas dynamics codes, internal combustion engine cycle analysis codes other than turbine and ramjet engines, and general internal and external aerodynamic analysis codes. Listings of the subprograms comprising this thesis are located in the Appendix.