Leakage Characteristics in a Channel Consisting of a Serrated Wall

Labyrinth seals as a type of non-contact seal have been used very often in gas turbine and in many kind of fluid machines. They have various type of shapes. Most of them had been designed from the view point of very practical use and it is difficult to explain their characteristics. However, one of the fundamental design policies of labyrinth seal is to design the configuration which can produce larger differential leakage in the direction of fluid flow. Especially, if there is a periodical variation of pressure difference between both sides of labyrinth seal or there is reciprocal pressure difference, it is very significant in the seal performance to have large difference of leakage in the direction of flow.

In this research work, variation of leakage and fluid resistance depending on the flow direction were investigated for the narrow flow path. This narrow path is composed of irregular walls and smooth walls which have geometrically simple right angled triangle having non-symmetrical shape in upper stream and down stream in any point on the wall. Significant result that the maximum difference of leakage depending on the flow directions reached approximately 80% was obtained.