Labyrinth seals are widely used in rotating fluid machinery, due to its simplicity, low-cost and reliability. In this paper, the effect of cavities on leakage loss in straight-through labyrinth seals are studied by changing gas condensability. The fluid flow characteristics through straight-through labyrinth seals are obtained by using viscous flow analysis along with a RNG k-ε turbulence model. The numerical calculation and various gas pressure is that leakage of compressible gas is greater than that of incompressible gas. The result is investigated by the heating effect of labyrinth seal and density characteristics of compressible gas.

Computation Fluid Dynamics (CFD) has been employed to calculate the pressure, flow distributions and leakage of brush seal by using Reynolds-Averaged-Navier-Stokes (RANS) method and two-dimensional axisymmetric anisotropic porous medium model. The leakage in brush seal with radial clearance has a marked increase compared with contact brush seal. The leakages of brush seal with different radial clearances have been investigated comparing contact brush seal. A type ofretaining ring structure has been employedto reduce the leakage on radial clearance condition. Also the disturbance effect of retaining ring on bristle pack has been studied.

Mechanical seal face texturing has the advantage of improving mechanical seal performance, such as improving opening force, reducing friction coefficient and minimizing wear and so on. In this paper, mechanical seal face, composed of sintered silicon carbon(S-SiC), is textured by the acoustic-optic Q-switched pulsed Nd:YAG laser in multi-mode. The micro-dimples are produced in mechanical seal face, and the profiles are measured by scanning electron microscopy (SEM) and 3D white light interference surface morphology apparatus. Results show that it is in the focus plane that maximal depth and minimum diameter appear and the circular profile of the micro-dimple can be acquired. And the diameter of micro-dimple increases with the increasing of single pulse energy reaching a saturation value at about 3.8mJ, but the increasing of single pulsed energy will reduce the depth of micro-dimple in a small range.