Subtranscritical and Supercritical Properties for LO2-CH4 at 15MPa

Abstract

Future launchers will use rocket propulsion systems burning CH 4 /LO 2 at high chamber pressure, and so it is useful to analyze the thermophysical properties of these species and their combustion products at these conditions. High-pressure (real-gas) effects significantly modify combustion regimes, for instance, the propellants Re injected near the critical temperature, and so to simulate mixing and combustion processes in subtranscritical regimes high-pressure effects must be described. This paper analyzes the compressibility factors of CH 4 , O 2 , CO 2 , and H 2 O at a pressure of 15 MPa and calculates the difference between ideal- and real-gas thermophysical properties for these species in the range of temperature in which experimental data are available. Finally, the paper describes thermophysical properties at typical liquid rocket engine combustion chamber conditions (100 < T < 6000 K, 15 MPa) by polynomial fits. As there are no experimental data at high temperatures, theories are necessary to predict properties at temperatures different from the experimental ones: thus, low-temperature experimental data (National Institute of Standards and Technology tables) are used in conjunction with predictions obtained with the Lee-Kesler equation of state (for density and isobaric specific heat) and with the Chung et al. method (for viscosity and thermal conductivity). This paper will try to clarify the impact of subtrans-supercritical parameters on mixing and combustion in future liquid rocket engines.