Xiangkai Meng

Experiment on Wear Behavior of High Pressure Gas Seal Faces

Current researches show that mechanical deformation of seal ring face makes fluid film clearance decrease at high pressure side, thus a divergent clearance is formed and face wear occurs more seriously at the high pressure side than that on the low pressure side. However, there is still lack of published experimental works enough to prove the theoretical results. In this paper, a spiral groove dry gas seal at high pressures is experimentally investigated so as to prove the face wear happened at the high pressure side of seal faces due to the face mechanical deformation, and the wear behavior affected by seal ring structure is also studied. The experimental results show that face wear would occur at the high pressure side of seal faces due to the deformation, thus the leakage and face temperature increase, which all satisfies the theoretical predictions. When sealed pressure is not less than 5 MPa, the pressure can provide enough opening force to separate the seal faces. The seal ring sizes have obvious influence on face wear. Face wear, leakage and face temperature of a dry gas seal with the smaller cross sectional area of seal ring are less than that of a dry gas seal with bigger one, and the difference of leakage rate between these two sizes of seal face width is in the range of 24%–25%. Compared with the effect of seal ring sizes, the effect of secondary O-ring seal position on face deformation and face wear is less. The differences between these two types of dry gas seals with different secondary O-ring seal positions are less than 5.9% when the rotational speed varies from 0 to 600 r/min. By linking face wear and sealing performance changes to the shift in mechanical deformation of seal ring, this research presents an important experimental method to study face deformation of a dry gas seal at high pressures.

Thermohydrodynamic analysis on herringbone-grooved mechanical face seals with a quasi-3D model

A quasi-3D thermohydrodynamic model was introduced to analyze the seal performance of a herringbone-grooved mechanical face seal. In the model, the heat conduction equations of the seal rings and the energy equation of the lubrication film were solved simultaneously by the streamline upwind/Petrov–Galerkin finite element method. The Reynolds equation and the temperature equations were iteratively solved to obtain the liquid film pressure and the temperature distribution. A parameterized study was conducted to analyze the influence of the herringbone grooves’ geometry on the opening force, leakage rate, friction coefficient, and temperature rise. The results show that the hydrodynamic analysis overestimates the opening force because the viscous heat reduces the dynamic viscosity. The longer and narrower inner spiral groove gives the smaller leakage rate and the longer outer spiral groove with a smaller spiral angle shows the larger opening force.