Session: 40-04: Turbine Cavity Flows and Flowpath Geometry Effects I

Paper Number: 152791

An Experimental and Numerical Investigation of the Rotordynamic Coefficients of a Gas Labyrinth Seal: Part 1 – Experimental Results 

This paper is the first of a two-part series investigating the rotordynamic behavior of a six-tooth gas labyrinth seal. Part 1 focuses on the experimental work, presenting a detailed description of the test rig, rotordynamic coefficients, and leakage values obtained at various operating conditions. The seal was tested across three pressure ratios (0.2, 0.3, and 0.4) and three rotor speeds (5, 10, and 15 krpm). The supply pressure was maintained at 13.1 bars, with discharge pressure adjusted through a back pressure valve to achieve the desired ratios. The rotordynamic coefficients were obtained by pseudo-random excitation of the seal at subsynchronous frequencies with different waveform amplitudes. Five waveforms were used: three individual frequency waveforms -- 50, 100, and 150 Hz -- and two multi-frequency waveforms -- 50-150 Hz and 10-350 Hz. Frequency independence of the rotordynamic coefficients was observed at low and medium frequencies, while at high frequencies the dynamic stiffness increased with increasing frequency. Results of the rotordynamic coefficients were compared using the individual and multi-frequency waveforms values for 50, 100, and 150 Hz at the specified pressure ratios. Additionally, the influence of the cross-coupled stiffness on effective damping was analyzed. Part 2 of this series explores the computational aspects, including a grid independence study and comparison between experimental and numerical results.

Presenting Author: Ciprian Comsa Texas A&M University - Department of Aerospace Engineering

Presenting Author Biography: Ciprian Comsa is a third-year PhD. candidate in Aerospace Engineering at Texas A&M University. He earned his Bachelor of Science in Mechanical Engineering from the University of Missouri - Columbia. His research focuses on numerical simulations and experimental work of gas flow in annular seals. A retired professional chess player, Ciprian enjoys playing chess with his office mates during lunch breaks.

Authors:

Ciprian Comsa Texas A&M University - Department of Aerospace Engineering
Seung Hyeop Hyun Texas A&M University - Turbomachinery Laboratory
Adolfo Delgado Texas A&M University - Department of Mechanical Engineering
Paul Cizmas Texas A&M University - Department of Aerospace Engineering