Abstract:Based on the nonlinear vibration principle,the axial vibration dynamic model of the rotorbearingdry gas seal system was established.The influence of spiral angle and spiral groove depth on system stability was analyzed,and the results were compared with those obtained by only considering the dry gas seal system.In specific conditions,the axial nonlinear gas film stiffness and damping was calculated and fitted,by substituting it into the free vibration equation,a three order nonlinear double freedom forced vibration differential equation was obtained.The RungeKutta method was used to solve the equations,and the effect of the spiral angle on the vibration displacement of static ring was analyzed.The results show that the vibration displacement of the static ring is decreased first and then increased with the increasing of the spiral angle(from 765° to 80.0°),When the spiral angle id 78.50°,the vibration value is the smallest,the maximum amplitude is 7 μm,and the maximum vibration velocity is 25 μm/s.In the dry gas seal system considering the influence of rotor and bearing,the influence of spiral angle on the vibration of static ring is more significant.Changing the spiral angle can adjust and reduce the amplitude of the seal ring,while changing the spiral groove depth has little effect on the vibration amplitude of the static ring.The research shows that the vibration displacement of the seal ring can be minimized by properly increasing the helical angle (from 0.5° to 0.6°),thus ensuring the stable operation of the dry gas seal system.