CORRELATIONS FOR DETERMINING THERMODYNAMIC PROPERTIES OF HYDROGEN-HELIUM GAS MIXTURES AT TEMPERATURES FROM 7000 to 35 000 K

摘要

Simple relations for determining the enthalpy and temperature of hydrogen-helium gas mixtures have been developed for hydrogen volumetric compositions from 1.0 to 0.7. These relations are expressed as a function of pressure and density and are valid for a range of temperatures from 7000 to 35 000 K and pressures from 0.10 to 3.14 MPa. The proportion¬ality constant and exponents in the correlation equations were determined for each gas com¬position by applying a linear least-squares curve fit to a large number of thermodynamic calculations obtained from a detailed computer code. Although these simple relations yielded thermodynamic properties suitable for many engineering applications, their accuracy was improved significantly by evaluating the proportionality constants at postshock conditions and correlating these values as a function of the gas composition and the product of free-stream velocity and shock angle. The resulting equations for the proportionality constants in terms of velocity and gas composition and the corresponding simple relations for enthalpy and temperature were incorporated into a flow-field computational scheme. Comparison was good between the thermodynamic properties determined from these relations and those obtained by using a detailed computer code to determine the properties. Thus, an appreciable savings in computer time was realized with no significant loss in accuracy.