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Frozen chemistry effects on nozzle performance simulations
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Georgiadis, Nicholas J. Yoder, Dennis A. O'Gara, Michael R. |
| Copyright Year | 2009 |
| Description | Simulations of exhaust nozzle flows are typically conducted assuming the gas is calorically perfect, and typically modeled as air. However the gas inside a real nozzle is generally composed of combustion products whose thermodynamic properties may differ. In this study, the effect of gas model assumption on exhaust nozzle simulations is examined. The three methods considered model the nozzle exhaust gas as calorically perfect air, a calorically perfect exhaust gas mixture, and a frozen exhaust gas mixture. In the latter case the individual non-reacting species are tracked and modeled as a gas which is only thermally perfect. Performance parameters such as mass flow rate, gross thrust, and thrust coefficient are compared as are mean flow and turbulence profiles in the jet plume region. Nozzles which operate at low temperatures or have low subsonic exit Mach numbers experience relatively minor temperature variations inside the nozzle, and may be modeled as a calorically perfect gas. In those which operate at the opposite extreme conditions, variations in the thermodynamic properties can lead to different expansion behavior within the nozzle. Modeling these cases as a perfect exhaust gas flow rather than air captures much of the flow features of the frozen chemistry simulations. Use of the exhaust gas reduces the nozzle mass flow rate, but has little effect on the gross thrust. When reporting nozzle thrust coefficient results, however, it is important to use the appropriate gas model assumptions to compute the ideal exit velocity. Otherwise the values obtained may be an overly optimistic estimate of nozzle performance. |
| File Size | 2841770 |
| Page Count | 30 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20090015378 |
| Archival Resource Key | ark:/13960/t24b82d1r |
| Language | English |
| Publisher Date | 2009-03-01 |
| Access Restriction | Open |
| Subject Keyword | Fluid Mechanics And Thermodynamics Performance Tests Exhaust Nozzles Mass Flow Rate Nozzle Flow Computational Fluid Dynamics Simulation Gas Flow Exhaust Gases Ideal Gas Nozzle Thrust Coefficients Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
