Axial flow compressors of Gas turbines use labyrinth seals to prevent the backflow of the working fluid. However some fluid will leak through the seals due to the clearance provided between the stationery and rotating components and due to the pressure difference across the seals, which affects the efficiency. The geometric shape of the seal plays an important role in influencing the fluid flow through the seals and the leakage rate.
The flow through the seals consists of the primary flow and the secondary flow. The secondary flow is the flow through the cavity which is associated with vortex currents and tends to obstruct the primary flow. The geometric shape of the cavity is varied to study its effect on the vortex and resultant leakage flow through the seals.
The curvatures of the seal and the distance of the seal tip to the end of the seal are the main parameters considered to arrive at the desired cavity which helps to create the required whirling action and to reduce the velocity of the leakage flow.
Gambit software is used for modeling the geometry and Fluent software is used for the analysis. Axi-symmetric pressure based analysis is carried out using the standard κ-ε turbulence. The results of the standard cavity are compared with different variants.
The flow velocity and mass flow is studied at different locations of the seal. The results indicate that by optimizing the shape of the seal cavity, the leakage through the labyrinth seal can be reduced.