Comparative Analysis of Helically Grooved and Circumferentially Grooved Labyrinth Seal

Labyrinth seals are used in turbo-machinery for reducing the leakage of working fluid. The energy lost by the fluid passing through the gap between labyrinth seal and rotor causes the reduction in leakage rate. But the fluid in between the labyrinth seal and rotor induce various forces (radial and tangential forces). These forces can be represented by certain numbers of coefficients, such as stiffness and damping coefficients. In this work, a comparative analysis has been carried out between a helicallygrooved and a circumferentially-grooved labyrinth seal using a CFD program Fluent. Parameters such as fluid forces, leakage and rotordynamic coefficients for both the labyrinth seals are calculated. Modelling and analysis have been performed with seal-rotor configurations having different eccentricity ratios (0.1, 0.2, 0.34, 0.4, 0.5 and 0.68). Leakage and rotordynamic coefficients have been calculated and compared for the two seals under different inlet pressures, rotor speed, etc. The calculated leakage was same for both the labyrinth seals, but the calculated rotordynamic coefficients were different.