Supercritical combustion properties

A. Congiunti, C. Bruno, E. Giacomazzi

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12 Citations (Scopus)

Abstract

During the last decades the demand for higher performance in liquid rocket engines has driven chamber pressure upwards. Nowadays the pressure of the totality of cryogenic rocket engines in production is well above critical for all propellants if not all combustion species. The same may not be said of temperature, typically below critical for many propellant combinations. In order to simulate mixing and combustion processes in the supercritical regime, effects due to high-pressure, real-gas behavior must therefore be included. The aim of this work is to examine the physics of real gas and to compare results obtained by the use of several methods to compute high-pressure molecular transport properties such as viscosity and thermal conductivity. As a first step, a comparison between different equations of state (EOS) has been performed; from simple cubic (Redlich-Kwong, Soave, Peng- Robinson) to more complex equations of state (e.g., Lee-Kesler), with particular attention to accuracy, range of applicability, suitability for different species and mixtures, and also impact on computational time. Species considered are those of interest in cryogenic engines with a look to future space transportation systems utilizing CH4/ O2 (of interest in Europe right now) but also LOX/LH2. Thermodynamic properties derived directly from equations of state have also been recalculated. The same comparison was also performed for transport properties using different estimation method (Chung et al, Lucas, Ely and Hanley). Knowledge of these effects may modify significantly combustion regimes: for instance, by substantially raising local Re of injected streams near the critical temperature. Results indicate that cubic equations of state are very effective in predicting PVT behavior of most substances, close to the critical point and up to about Tr = 2, where errors can become important (30%). More complex EOS are very accurate but computational efforts make their use in CFD codes undesirable. As far as transport properties are concerned, none of the methods analyzed seems to indicate a clear superiority over the others; their use depends strongly on how the code is formulated (e.g., pressure-based or density-based) and on whether they need to describe pure real gases or mixtures of real gases. Golovitchev and Bruno (1996) showed that real gas thermodynamic properties modified the ignition regime of a model GH2/LOX rocket simulating a single coaxial injector of the SNECMA Vulcain Mk 1 engine. This paper is to be considered a contribution toward better understanding of the impact of supercritical parameters on mixing and combustion in future liquid rocket engines. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Original languageEnglish
Publication statusPublished - 2003
Event41st Aerospace Sciences Meeting and Exhibit 2003 - , United States
Duration: 1 Jan 2003 → …

Conference

Conference41st Aerospace Sciences Meeting and Exhibit 2003
CountryUnited States
Period1/1/03 → …

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All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Aerospace Engineering

Cite this

Congiunti, A., Bruno, C., & Giacomazzi, E. (2003). Supercritical combustion properties. Paper presented at 41st Aerospace Sciences Meeting and Exhibit 2003, United States.