Graduation Semester and Year
Summer 2025
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Aerospace Engineering
Department
Mechanical and Aerospace Engineering
First Advisor
Daejong Kim
Second Advisor
Frank Lu
Third Advisor
Hyejin Moon
Fourth Advisor
Michael Bozlar
Fifth Advisor
Robin Macaluso
Abstract
Gas foil thrust bearings (GFTBs) are contactless bearings that offer advantages such as lightweight construction and the ability to accommodate misalignments and geometric irregularities. However, their load capacity is lower than rigid or magnetic bearings. The structure and geometry of the foil significantly influence GFTB performance. The taper-flat design is the most used configuration due to its effectiveness and ease of implementation. Key parameters in designing this geometry include taper ratio, taper height, orifice size, and orifice location. These parameters must be optimized alongside manufacturing constraints to produce an effective GFTB. This study presents a design optimization investigation of various taper configurations and orifice placements using numerical simulations to determine the most effective geometry. Following the simulation phase, a performance comparison was conducted between two thrust bearing configurations: a Hybrid Rigid Thrust Bearing (HRTB) and a Hybrid Foil Thrust Bearing (HFTB). Both bearings shared identical geometries, including an 82 mm outer diameter, taper angles, and orifice characteristics. Their performance was evaluated under hydrostatic, hydrodynamic, and hybrid operating conditions through simulation and experiment. Simulation results showed that the HRTB demonstrated superior load capacity in hydrodynamic mode, while the HFTB performed better under hydrostatic conditions. In hybrid 2 mode, experiments were conducted at varying speeds to assess load capacity and power loss. The HFTB achieved a load capacity of approximately 400 N at 40,000 RPM. Although simulations projected better load performance from the HRTB, experimental validation was hindered by air hammering instability. To address this, a damping mechanism was introduced behind the HRTB’s backplate to evaluate its effectiveness in suppressing pneumatic hammering. The outcomes of this work offer insights into the performance trade-offs between rigid and foil thrust bearings and challenge the prevailing industry preference for foil bearings, suggesting that a well-designed rigid bearing may offer superior performance. The study provides practical guidelines for general thrust bearing design development.
Keywords
hybrid foil bearing, thrust bearing, foil thrust bearing, rigid bearing, hybrid thrust bearing, air hammering, taper ratio, taper optimization, gas bearing
Disciplines
Aerodynamics and Fluid Mechanics | Other Mechanical Engineering | Tribology
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Ebewele, Ehiremen, "DESIGN STRATEGY FOR HYBRID THRUST AIR BEARINGS: COMPARATIVE ANALYSIS OF RIGID VS. FOIL BEARINGS CONSIDERING OPTIMUM TAPER ANGLE AND ORIFICE LOCATION WITH EXPERIMENTAL VALIDATION" (2025). Mechanical and Aerospace Engineering Dissertations. 430.
https://mavmatrix.uta.edu/mechaerospace_dissertations/430
Included in
Aerodynamics and Fluid Mechanics Commons, Other Mechanical Engineering Commons, Tribology Commons