Session: 40-03: Compressor Secondary Flows and Interactions

Paper Number: 153994

An Experimental and Numerical Investigation of the Rotordynamic Coefficients of a Gas Labyrinth Seal: Part 2 - Numerical Simulation Revised Version 

Part 1 of this paper presented the experimental analysis of the rotordynamic behavior of a six-tooth gas labyrinth seal. In part 2, the computational aspects were explored, including a grid independence study and a comparison between experimental and numerical results. The numerical results include predictions from both a bulk flow model and a computational fluid dynamics (CFD) model that solved the Reynolds-averaged Navier--Stokes (RANS) equations. A grid independence study was conducted in both the meridional plane and circumferential direction using four different node configurations for both studies. A grid that offered a good compromise between computational cost and solution accuracy was determined. After ensuring grid independence, the quasi-steady state method was employed using combinations of four different subsynchronous precessional frequency ratios (PFR) to find the rotordynamic coefficients. Additionally, the shaft was statically displaced 5, 10, and 20 percent of the radial clearance and it was found that the solution did not vary with displacement.  A 10 percent displacement was chosen to conduct the numerical simulations.  The bulk flow model and CFD results were compared to experimental results showing good agreement with experimental results exhibiting frequency independence behavior. However, when frequency dependence behavior was observed, the direct damping coefficient was underpredicted by both the bulk flow model and CFD.  Furthermore, the leakage was overpredicted by the numerical results. Because the direct damping coefficient was underpredicted and the leakage was overpredicted, the numerical results were considered conservative. It was also found that refining the mesh improved the agreement between experimental and CFD results, underscoring the importance of mesh choice in accurately modeling the seal's behavior. Finally, the CFD prediction outperformed the bulk flow model, but the computational cost of the CFD simulations far exceeded that of the bulk flow model.

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

Presenting Author Biography: Ciprian Comsa is a third-year Ph.D. 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 analysis 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
Paul Cizmas Texas A&M University - Department of Aerospace Engineering