Experiment and CFD Analysis of Plain Seal, Labyrinth Seal and Floating Ring Seal on Leakage Performance

This paper investigates the leakage characteristic of a non-contact cryogenic seal applied through experiment and CFD analysis. Plain seal (PS), labyrinth seal (LS), and floating ring seal (FRS) were designed for leakage performance test of cryogenic environment. ANSYS Fluent (18.2) was used for creating the flow field of the sealing unit for leakage performance analysis. In order to validate the CFD analysis results, the leakage experimental performance test was also conducted in a cryogenic environment. To create a cryogenic environment, liquid nitrogen (83K) was injected into the test chamber at 0.5 bar, and the test time for each seal was 5,000 s. The results show that among the three types of seals, the FRS had the smallest leakage and the amount of leakage converged quickly. It was confirmed that the largest turbulent kinetic energy was generated when an FRS was used. Also, FRS effectively reduced leakage compared to PS and LS due to the characteristic that clearance changes according to pressure difference. After the leakage performance test, the wear characteristic according to the seal shape was analyzed through surface roughness measurement. In the case of PS, the wear of the surface progressed considerably more than the FRS. Inadequate fluttering adversely affects the wear and leakage performance of the seal. It was found that the wear of PS due to thermal contraction accelerated the friction, and in contrast, the FRS had less friction even with thermal contraction.