Lubricating gas is generally considered as ideal gas in the study of dry gas seal. However

the behavior of real gas is quite different from that of ideal gas under high pressures. In this study

the virial equation was used to express the behavior of gas to obtain a Reynolds equation for gas lubricating

modified by the effect of real gas. The Reynolds equation was solved by perturbation method and finite difference method to obtain the pressure distribution

and the dynamic characteristic parameters of dry gas seal

such as gas film stiffness and gas film damping

were obtained. As to the T-groove dry gas seal

carbon dioxide (CO2)

hydrogen (H2) and nitrogen (N2) were taken as examples to analyze the influence of real gas upon the gas film stiffness and gas film damping of T-groove dry gas seal

which were compared with those of ideal gas. The results show that the gas film stiffness and gas film damping of the three real gases and ideal gas increase with the squeeze number. Gas film stiffness of the real gas and ideal gas increase with the increase of frequency number

while the gas film damping decreases. The deviations of the film stiffness and gas film damping of real gas from those of ideal gas increases with the derivation of compressibility number Z from ideal gas (Z=1). For CO2 (Z<1)

its gas film stiffness is larger than that of ideal gas

while the gas film damping is smaller. For H2 (Z>1)

its gas film stiffness is smaller than that of ideal gas

but the gas film damping is larger. For N2 (Z≈1)

both the gas film stiffness and gas film damping are approximately equal to those of ideal gas.