Session: Student Poster Competition

Submission Number: 186987

Optimization of Honeycomb Seal Clearance Ratios for High-Pressure/temperature Supercritical Carbon Dioxide Within Labyrinth Seals 

As supercritical carbon dioxide power cycles emerge as a high-efficiency alternative to traditional steam cycles, the development of specialized turbomachinery components becomes critical. Among these, labyrinth seals with honeycomb facings are essential for managing leakage and ensuring rotordynamic stability; by minimizing losses, these seals directly enhance the overall cycle efficiency. However, the high density and low viscosity of sCO2 create unique aerodynamic challenges that make standard air-based seal correlations inadequate. The high fluid density and low viscosity of sCO2 result in substantially higher Reynolds numbers and thinner boundary layers compared to air, which alters the interaction between the fluid and the honeycomb cavities. This study will investigate the optimization of honeycomb geometric parameters (cell diameter, radial clearance, etc.) with sCO2 as the working fluid.

Numerical simulations will be utilized with constant inlet boundary conditions of 200 bar and 300°C in order to maintain the CO2 in a supercritical state. Despite the high temperature, the pressure keeps the fluid from being considered an ideal gas, leading to the use of a real-gas model in the simulations. The design will have a fixed labyrinth seal design, with the honeycomb only having changes to its design. By running at different pressure ratios (inlet/outlet), the data will be examined towards differences in mass flow rate and temperature, analyzing changes in leakage through the discharges across each experiment. The parameters of the honeycomb will be based on industry standards, with varying sizing dependent on previous work in the field. The results will provide a design map for sCO2 seal optimization, demonstrating that the optimal cell size is highly sensitive to the thin boundary layers characteristic of high-pressure CO2 environments.

Presenting Author: Jesse Chotiner University of Central Florida

Presenting Author Biography: 3rd year undergraduate student at UCF going into their senior year towards a B.S. in Aerospace in Engineering. Undergraduate researcher with the Applied Energy Systems Group at CATER, working on projects dealing with sCO2 power generation. Also a student of the Burnett Honors College, worked as an Honors Orientation Ambassador in Summer 2024 and an Honors Symposium Team Leader in Fall 2025.

Authors:

Jesse Chotiner University of Central Florida
Ghanshyam Mandal University of Central Florida
Jayanta Kapat University of Central Florida
Erik Fernandez University of Central Florida
Marcel Otto University of Central Florida