Session: 27-02: Damping, Stability, Swirl-Induced Effects & Seal Dynamics.

Submission Number: 178097

Evaluating the Effect of Swirl Brake Vanes on Stability for a First-Stage Centrifugal Compressor in Supercritical CO2 Off-Design Applications Using Transient Computational Fluid Dynamic Analysis 

In rotating machinery, such as centrifugal compressors and turbines, the fluid forces acting on the rotor from components such as labyrinth seals, balance piston seals, and impeller blades affect rotordynamic stability and must be accounted for to ensure that the rotor has been sufficiently designed for the compressor’s operating range. In this study, the first stage of a supercritical CO₂ (sCO₂) centrifugal compressor was analyzed using transient computational fluid dynamic (CFD) simulations to predict the rotordynamic force coefficients of the eye seal and impeller front shroud at off-design conditions. The predicted forces and prescribed mesh motion were used to calculate the eye seal and front shroud impedance matrices for two geometry cases: a front cavity with swirl brake vanes and a front cavity without swirl brake vanes. A unique moving-wall transient method was employed with a multi-frequency whirling motion, allowing the rotordynamic coefficients to be obtained from a single CFD model but separately evaluating the impeller eye seal and the shroud forces. The rotordynamic coefficients for these simulations were used to evaluate the swirl brake vane performance at near-surge and near-choke conditions. Lastly, the front shroud rotordynamic coefficients were compared to typical empirical methods for predicting impeller cross-coupled stiffness and the labyrinth eye seal rotordynamic coefficients were compared to bulk-flow predictions.

Presenting Author: Mark Anguiano Southwest Research Institute

Presenting Author Biography: Mr. Mark Anguiano is a Research Engineer in the Rotating Machinery Development Section of the Machinery Department at Southwest Research Institute in San Antonio, TX. His research experience includes the design and testing of components such as dry gas seals and cryogenic pumps. Mr. Anguiano has also designed and analyzed the turbine combustor case for a 300 MWe Allam cycle turbine concept according to ASME Boiler and Pressure Vessel Code (BPVC) Sec. VIII, Div. 2. He also led the development of a parametric tool for CO2-equivalent emissions impact from dry gas seal vents, designed ancillary systems (lube oil, dry gas seal) for turbine and compressor powertrains, and conducted several computational fluid dynamic (CFD) based rotordynamic stability analyses. Mr. Anguiano earned his Bachelor and Master of Science degrees in Mechanical Engineering from the University of Texas at San Antonio.

Authors:

Mark Anguiano Southwest Research Institute
Chris Kulhanek Southwest Research Institute
Aaron Rimpel Southwest Research Institute
Subhra Shanka Koley Southwest Research Institute
Jeffrey Moore Southwest Research Institute