Term of Award
Summer 2025
Degree Name
Master of Science, Mechanical Engineering
Document Type and Release Option
Thesis (restricted to Georgia Southern)
Copyright Statement / License for Reuse
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
The world is ever industrializing. A heightened energy demand is prevalent in societies all over the world, and as the global population increases, alternative energy sources must be made more efficient to meet this energy demand. Large inefficiencies exist in the collection methods of alternative energy sources. These collection methods widely rely on steam turbomachinery due to its practicality in industry; however, a lack of efficiency is present within this turbomachinery. A novel turbomachinery solution shows potential for improving efficiency. This type of turbomachinery utilizes supercritical carbon dioxide, an energy dense working fluid that provides benefits in energy collection. This solution has the potential to improve the cycle efficiencies to over %50. Research efforts outlined in this study aim to address shortcomings of this technology to effectively improve its practicality for full-scale usage within industry. Although it is promising, this technology is novel. Sealing technology is a glaring drawback, and there is a high leakage at the output shaft while the system starts up and is operational. A promising solution for this leakage, the elastohydrodynamic (EHD) seal, has the potential to reduce leakages to a level that promotes efficiency. This seal operates by creating a minimal clearance surrounding the shaft with a sleeve-like structure, which deforms elastically when the high-pressure operating conditions of the system are imposed (10-35 MPa, 300-700 °C). This paper aimed to further the understanding of EHD seals by investigating the effects of geometric properties on the seal’s performance. An iterative approach with four different seal configurations was explored. Seals were manufactured from virgin PEEK material to operate within the rated pressure range of the test rig. The seal with 0.06" thickness and 1" length yielded a maximum leakage rate of 7.9 g/s; the one with 0.1" thickness and 1" length resulted in a maximum of 13.7 g/s; the seal with 0.06" thickness and 0.5" length produced a maximum of 17.4 g/s; the one with 0.08" thickness and 0.5" length resulted in a maximum leakage rate of 19.5 g/s; and the seal with 0.1" thickness and 0.5" length generated a maximum leakage rate of 24.3 g/s. The results indicate that longer seal lengths result in lower leakage rates, while thicker seals lead to higher leakage rates, which agrees with the hypothesis for seal performance. These findings could serve as the foundation for the optimal design of EHD seals in future studies.
Recommended Citation
Sercer, George R., "Experimental Study on Geometric Influences on Elastohydrodynamic Seal Leakage" (2025). Theses & Dissertations. 3007.
https://digitalcommons.georgiasouthern.edu/etd/3007
Research Data and Supplementary Material
No
