Session: 23-08 Annular Seals

Paper Number: 152577

Leakage and Rotordynamic Characteristics for Three Types of Annular Liquid Seals Operating in a Liquid Hydrogen Turbopump 

In this paper, three types of annular liquid seals were designed for the inter-stage location of a cryogenic liquid hydrogen turbopump, in efforts to limit internal leakage flow and achieve rotordynamic stability. These three seals represent the main seal types used in high-speed rotating machines, including a labyrinth seal (LABY), a fully-partitioned pocket damper seal (FPDS), and a hole-pattern damper seal (HPS). To enhance the seal net damping capability at high inlet preswirl condition, a straight swirl brake was also designed and employed at seal entrance for each one of these three seals, having the same sealing clearance, diameter and axial lengths. To present a comprehensive assessment and comparison on the leakage and rotordynamic characteristics, leakage flow rates, rotordynamic force coefficients, cavity dynamic pressure, and swirl velocity developments were calculated and analyzed for these three seals, using a proposed transient computational fluid dynamic (CFD)-based perturbation method based on the multiple-frequency elliptical-orbit rotor whirling model. To take into account of the thermodynamic effect and the weak compressibility of the liquid hydrogen, a table look-up procedure based on the National Institute of Standards and Technology (NIST) reference fluid properties database was implemented, using an in-house code, for the fluid properties of liquid hydrogen in supercritical and high pressure difference conditions. Results show that from a rotordynamic viewpoint, the HPS seal with entrance swirl brake is a better seal concept for the present cryogenic liquid hydrogen turbopump, which possesses the largest positive effective damping throughout the entire subsynchronous frequency range.

Presenting Author: Zhigang Li Xi'an Jiaotong University

Presenting Author Biography: Zhigang Li is a professor in the Institute of Turbomachinery at Xi’an jiaotong University. His research interests are in advanced sealing and gas bearing techniques of turbomachinery. He has over 50 peer reviewed publications on AIAA Journals and ASME Journals, and has given several invited, keynote, and plenary lectures at international conferences.

Authors:

Xiaoqiang Ye National Key Laboratory of Aerospace Liquid Propulsion
Haiyan Luo Xi'an Jiaotong University
Wei Shen Nuclear and Radiation Safety Center
Zhigang Li Xi'an Jiaotong University
Jun Li Xi'an Jiaotong University