0
research-article

EXPERIMENTAL STUDY OF THE LEAKAGE AND ROTORDYNAMIC COEFFICIENTS OF A LONG SMOOTH SEAL WITH TWO-PHASE, MAINLY-OIL MIXTURES

[+] Author and Article Information
Min Zhang

Development Specialist, Praxair, Inc., Tonawanda, NY, USA
hitzhangmin@gmail.com

Dara Childs

Leland T. Jordan Professor, Texas A&M University, College Station, TX, USA
dchilds@tamu.edu

Jimmy McLean

Graduate Research Assistants, Texas A&M University, College Station, TX, USA
james.mclean.jr@gmail.com

Dung L. Tran

Graduate Research Assistants, Texas A&M University, College Station, TX, USA
trandung90@tamu.edu

Hari Shrestha

Graduate Research Assistants, Texas A&M University, College Station, TX, USA
ktmhari.shrestha@gmail.com

1Corresponding author.

ASME doi:10.1115/1.4042272 History: Received July 10, 2018; Revised December 05, 2018

Abstract

This paper experimentally studies the leakage and rotordynamic performance of a long-smooth seal with air-oil mixtures. Tests are performed with inlet gas-volume-fraction GVF=0%, 2%, 4%, 6%, and 10%, rotor speed ?=5, 7.5, 10, and 15 krpm, inlet temperature Ti=39.4 °C, exit pressure Pe=6.9 bars, and pressure drop PD=31, 37.9, and 48.3 bars. Test results show that adding air into the oil flow does not change the seal's mass flow leakage m ? discernibly but significantly impacts the seal's rotordynamic characteristics. For all PDs and speeds, K increases as inlet GVF increases from zero to 10% except for 6%?inlet GVF?10% when PD=48.3 bars, where K decreases as inlet GVF increases. The K increment will increase a pump rotor's natural frequency and critical speed. Increasing the rotor's natural frequency would also increase the onset speed of instability (OSI) and improve the stability of the rotor. Adding air into the oil flow has little impact on cross-coupled stiffness k, direct damping C, and effective damping Ceff. Ceff=C-k/?+mq?, where mq is the cross-coupled virtual-mass. Test results are compared to predictions from San Andrés's [1] bulk-flow model, which assumes that the liquid-gas mixture is isothermal and homogenous. The model reasonably predicts m ?, C, and Ceff. All predicted K values are positive, while measured K values are negative for some test cases. Predicted k values are close to measurements when ?=5 krpm and are larger than measurements when 7.5???15 krpm.

Copyright (c) 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In