Modeling & Analysis of Labyrinth Seals Used in Steam Turbines

Labyrinth seals are used to provide a tortuous passage to help prevent leakage by allowing the fluid to pass through a long and difficult gap. Labyrinth seals on rotating shafts provide non contact sealing action by controlling the passage of the fluid through large no. of chambers by centrifugal motion as well as by the formation of controlled fluid vortices. The fluid that gets escaped from the main chamber becomes entrapped in the cavities of labyrinth where it is forced into a vortex like motion. During the service period of steam turbines, labyrinth seals which are mounted on the rotor, as the increase of wear rate in the labyrinth seal material it increases the clearance between the stator & rotor. If the wear rate & clearance is high, it causes the leakage of steam flow through the seals which effects the total efficiency of the steam turbine. The main objective of this work is to evaluate the leakage flow rate due to the clearance caused by the wear of the seal material in labyrinth seals by using CFD & adopting a new material (Silicon Carbide) to the labyrinth seals, thereby calculating the leakage flow rate and compare it with the theoretical calculated leakage flow rate using mathematical results.