The real gas property of carbon dioxide was expressed by third term virial equation

both the choked flow effect and the variation of gas viscosity were taken into account

the influence of inertia effect on the steady characteristics of pumping-inward and pumping-outward spiral groove dry gas seal (S-DGS) under laminar condition have been numerically investigated by referencing the theory of gas thrust bearing which considering inertia effect. Compared with the assumptions of ideal gas and inertialess

the results show that inertia effect induce a stronger influence on carbon dioxide real gas S-DGS. Inertia effect reduced leakage rate and opening force of pumping-inward S-DGS but the opposite was obtained for pumping-outward S-DGS. Taken pumping-inward S-DGS as example

the influence of inertia effect on the steady characteristics of carbon dioxide S-DGS (i.e. leakage rate and opening force) gradually enhanced with the increase of sealed gas pressure and rotational speed

while it being weaken with increased gas film thickness. The relative deviations of leakage rate and opening force caused by the inertia effect are 62.21% and 35.03% when sealed gas pressure is 10 MPa

gas film thickness is 3μm and rotational speed is 20000 r·min-1

and the critical entrance pressure which causes a choked flow at exit is improved. In addition

the closer the temperature of carbon dioxide is to its critical temperature

the more obvious the inertial effect is.