The preliminary design process of turbomachinery gas labyrinth seals requires fast, accurate and realistic estimate of seal flow rate. While the conventional analytical and theoretical bulk flow models can quickly predict labyrinth seal discharge characteristics, they lack the accuracy and pragmatism of modern CFD technique and vice-a-versa. This paper presents a new 1D loss model for straight-through gas labyrinth seal that can provide fast seal flow predictions with CFD-equivalent accuracy.&nbsp;The present seal loss model is developed using numerical experimentation technique. Multiple CFD computations are conducted on straight-through labyrinth seal geometries for a range of pressure ratios. A distinct post-processing methodology is developed to extract the through-flow stream tube in seal. Total pressure losses and flow area variations experienced by the flow in seal stream-tube are systematically accounted for based on well-known knife-to-knife (K2K) methodology. Regression analyses are conducted on the trends of variations of loss and area coefficients to derive the independent pressure loss and flow area correlations.These novel correlations are linearised and incorporated into the present seal loss model. It can predict bulk leakage flow rate, windage flow rate and inter-knife static pressures over a wide range of variation of flow and geometry modelling parameters.&nbsp; Validation study shows that the leakage mass flow rate predicted by this model is accurate within ±5% of experimental test data. This fast and accurate model can be employed for various applications such as, in a seal design-analysis workflow, for secondary air system (SAS) performance analysis and for the rotor-dynamic and aeroelastic modelling of seals.

Development of a New Loss Model for Turbomachinery Labyrinth Seals

Paper Proceedings: https://asmedigitalcollection.asme.org/GTINDIA/GTINDIA2021/volume/85536

ASME 2021 Gas Turbine India Conference (GTINDIA2021)

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