Brush seals are plausible replacements for conventional labyrinth seals in gas turbine internal air systems. They offer superior leakage performance due to their compliant nature and reduced effective clearance during operation. Nonetheless, strong swirling flows and aerodynamic loading on upstream bristles can trigger aeroelastic instability at high shaft speeds. To address this, the study examined grooves as a means of enhancing brush seal robustness by mitigating inlet swirl on the bristle pack. A parametric study of a simple groove geometry was conducted using Computational Fluid Dynamics (CFD) and a porous medium representation of the bristle pack. Then, a Design of Experiments (DOE) approach was applied to investigate a novel groove configuration. By combining a horizontal channel with an inclined groove, the design achieved greater spacing while maintaining swirl reduction through drag and mixing effects at the inner radius. Results confirmed that the new geometry effectively suppresses swirl, thereby reducing the risk of premature seal degradation and failure.

      The study was extended to evaluate grooved features over a range of engine-representative operating conditions. The key dimensionless quantities that describe the problem were identified. Pressure, temperature, leakage flow rate, swirl level, and shaft speed were varied to evaluate groove efficacy and to provide useful design insights. The results showed that the simulated groove was effective over the majority of the engine range, except for conditions where shaft rotation dominates over inlet swirl. The effect of seal clearance, either by design or due to in-service wear, and larger axial velocities in the seal, was shown to be significant in reducing groove de-swirl performance.

The other part of this research involved calibrating newly manufactured brush seal designs through porous‑medium modelling. A systematic methodology, informed by experimental data recently published at the University of Bath, was developed to determine the resistance coefficients of an aero‑engine brush seal. Seal leakage and radial pressure distributions were validated using a circular seal model, which successfully captured viscous and inertial resistance coefficients representative of the bristle pack. These coefficients were subsequently applied to a pressure‑relieving brush seal to examine alternative designs of pressure-balanced pockets aimed at improving performance. Furthermore, a fully resolved model of a hexagonal bristle pack was employed to assess the sensitivity of leakage and pressure to variations in inter‑bristle spacing.