The aim of this study was to identify the best structures of the honeycomb (or structures used instead of it) that can be applied to a seal cavity labyrinth in order to improve the sealing performance. The problem was investigated numerically using the ANSYS CFX commercial software.
The paper presents geometrical data concerning the proposed solutions to the labyrinth seal land structure. A simple straight-through labyrinth geometry with two leaned fins is analysed. Such a simple structure of the flow conditions was chosen to reduce the influence of other effects on the seal performance. Three-dimensional models of the labyrinth seal were elaborated for each honeycomb or honeycomb-like land structure. The following concepts were analysed: an inclination of the honeycomb cells, a land with different cell shapes (squeezed honeycomb) and honeycomb cells filled with a porous material. The labyrinth seals with different land structures were compared with two reference cases: a seal with a standard honeycomb land (with 1/8-inch cell size) and a seal with a smooth land. Calculations were performed for the pressure ratio values ranging from 1.08 to 1.8 and for varied sizes of the clearance.
Main parameters of the leakage flows are discussed. Additionally, the influence of the inlet narrowing on the seal performance is investigated. A qualitative assessment of the seal concepts is made and the most promising solutions are pointed out.