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

Abstract

Abstract. 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 flowrates 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 nondimensional 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.