Term of Award

Fall 2025

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Sevki Cesmeci

Committee Member 1

Priya Goeser

Committee Member 2

Prakashbhai Bhoi

Abstract

This thesis presents a numerical analysis and experimental verification approach for a novel elastohydrodynamic (EHD) seal designed with the specific application of supercritical carbon dioxide (sCO2) power cycles. Brayton power cycles with sCO2 as the working fluid have gained significant traction as potential large-scale power generation methods. This increase in interest and research is primarily due to their many beneficial characteristics, such as high thermal efficiency, compact geographic footprint, reduced capital costs, and lower water and fuel usage than comparable power cycles. Despite these many positive qualities, proper sealing technology remains one of the primary barriers to large-scale implementation. To address this, a novel elastohydrodynamic seal that leverages the proven elastohydrodynamic lubrication theory to form a non-contact, self-regulating throat region, thus minimizing leakage while avoiding excessive wear, is being studied. This study utilized a fully coupled, one-dimensional, axisymmetric COMSOL Multiphysics model to analyze the performance and behavior of the seal through outputs such as leakage rate, seal deformation, and pressure distribution along the seal. The model successfully computed these outputs for a PTFE seal at inlet pressures ranging from 0-0.75 MPa. Results showed that the peak leakage rate of 7.95 g/s occurred at an inlet pressure of 0.21 MPa, followed by a rapid reduction in leakage rate as pressures increased. Maximum deformation was also found to have a linear relationship with the inlet pressure, resulting in an R2 value of 0.929 for the full data set and 0.962 when neglecting the initial pressurization range of 0.2 MPa. The simulation model was able to converge quickly while consuming minimal computational resources with an overall solving time of less than ten seconds. When compared to previous experimental data, the simulation relatively accurately predicted the peak leakage rate along with the leakage behavior as the inlet pressure increased. In order to further validate the results of the simulation model, an experimental approach is also proposed with the goal of measuring both the leakage rate and the pressure distribution along the seal. Together, the simulation model and experimental methodology provide deeper insight into the behavior and performance of the proposed EHD seal.

Research Data and Supplementary Material

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