High-Speed Recessed Conical Hybrid Bearings with AM-Driven Large Gap Clearances for Integrated Bearing-Rotor Architectures of Gas Turbines: Navier-Stokes Analysis and Symbolic-Regression Correlations

Hydrostatic recessed conical bearings operating at high rotational speeds, commonly referred to as hybrid bearings, exhibit several advantages, including structural simplicity, reduced maintenance requirements, superior high-speed performance, increased load-carrying capacity, and lower noise and vibration. Existing hybrid-bearing research has so far primarily focused on small clearances, cavitation-free operation, and peripheral speeds up to roughly 90 m/s. However, advances in additive manufacturing now permit integrated, optimized bearing–rotor architectures, where clearances of 300 µm and turbomachinery-level peripheral speeds above 200 m/s are unavoidable. Under these conditions, the presence of recesses on a conical base, combined with three-dimensional flow effects and cavitation phenomena, renders classical hydrodynamic theory and existing design practices inadequate, thereby necessitating the use of new models. To address these challenges, a Design of Experiments approach, integrated with Navier-Stokes simulations, was employed to systematically analyze load capacity, frictional losses, and flow rates as a function of bearing geometry, clearance, supply pressure, recess configuration, semi-cone angle, rotational speed, and fluid properties. This study presents models derived via symbolic regression, capturing relationships among non-dimensional design parameters of high-speed hybrid bearings with large clearances under additive manufacturing constraints, complemented by design charts and simulation results to support efficient design and analysis.