Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals

Radial growth predictions of rotating labyrinth seals are conventionally obtained from one-dimensional analytical models. However, these predictions quantitatively differ within themselves by about 5-500%. Simulations using three-dimensional finite element method (FEM) are carried out in this paper for a typical labyrinth seal, subjected to high rotational speed and temperature, for a range of radius-to-length ratio of the rotor. Taking the predicted values by FEM as reference, four analytical models are assessed and their errors are quantified. These errors are found to be independent of rotational speed and temperature but significantly vary with the radius-to-length ratio of the rotor. Based on this finding, simple analytical models, together with correction factor charts, are suggested.