In the case of low speed and high pressure, the wear of dry gas seal is more serious, therefore, the preparation of DLC film by static ring is proposed, and the friction characteristics of the end face of the static and dynamic ring are analyzed with the groove structure. The dry gas seal with different spiral angle was tested by friction and wear machine, and the change law of temperature rise, friction coefficient and surface wear morphology were tested. The test results show that with the increase of load and speed, the friction temperature rises, friction coefficient and grinding mark of 16° spiral angle are less than 18°. Under the same working condition, the value of average friction coefficient of 18°spiral angle is 0.02 larger than that of 16°spiral angle, and the average friction temperature is increased by 5 ℃. On the one hand, because of the different spiral angle, the interface method is different and the wear degree of the end face of 18° spiral angle is greater than 16° spiral angle. On the other hand, with the increase of load and speed, the graphitization degree of DLC films is increased, which shows DLC films and spiral groove play a key role in the friction and wear of end faces. At the same time, it is found that the wear degree of the two kinds of spiral angle inner ring is greater than the outer ring, so the spiral groove can reduce the wear degree of the end face. The test results laid a foundation for the optimization design and practical application of spiral groove dry gas seal.

        The starting and stopping processes play an important role in reduce friction and abrasion of a spiral groove dry gas seal. Thus, the startup and shutoff of the seal is investigated by a numerical approach. The computational procedure based on the material properties of rotational and stationary rings, interaction of micro asperity, and frictional heat-flow coupling is implemented to build a three-dimensional thermo-mechanical coupling model considering sliding friction within rough-rigid body. And then, the ANSYS software is used to simulate the friction heat and the stress variation of rough-rigid body based on the characteristics of nonlinear multiphysics. The results are presented, and it shows that the maximum contact temperature value of the roughened surface increases with increase in the sliding time and presents a little fluctuation, and the distribution of VonMises equivalent stress is extremely nonuniform and non-linear. What’s more, the stress component of maximum x-direction(σ _xx) isn’t appeared in the region of highest contact asperity. The results reveal that a tensile stress is existed along the thickness direction of three-dimensional rough solid and the region of tensile stress is enlarged slightly with the sliding time. According to above results, it can be shown that increase in temperature and fluctuation are attributed to thermal conduction caused, the change of stress is due to the elastic-plastic deformation of asperities. These results illustrate the potential of numerical simulation in prediction the temperature and stress of seal faces during the starting and stopping process and may help in the design and optimization of spiral groove dry gas seal.