[논문]Stability Characteristics of Supercritical High-Pressure Turbines Depending on the Designs of Tilting Pad Journal Bearings

Lee, An Sung; Jang, Sun-Yong

doi:10.9725/kts.2021.37.3.99

Stability Characteristics of Supercritical High-Pressure Turbines Depending on the Designs of Tilting Pad Journal Bearings 원문보기

한국트라이볼로지학회지 = Tribology and lubricants, v.37 no.3, 2021년, pp.99 - 105

Lee, An Sung (Dept. of System Dynamics Research, Division of Mechanical Systems Safety Research, Korea Institute of Machinery & Materials) , Jang, Sun-Yong (R&D Center, Daedong Metal Industry Co.)

Abstract ▼ AI-Helper

In this study, for a high-pressure turbine (HPT) of 800 MW class supercritical thermal-power plant, considering aerodynamic cross-coupling, we performed a rotordynamic logarithmic decrement (LogDec) stability analysis with various tilting pad journal bearing (TPJB) designs, which several steam turbine OEMs (original equipment manufacturers) currently apply in their supercritical and ultra-supercritical HPTs. We considered the following TPJB designs: 6-Pad load on pad (LOP)/load between pad (LBP), 5-Pad LOP/LBP, Hybrid 3-Pad LOP (lower 3-Pad tilting and upper 1-Pad fixed), and 5-Pad LBPs with the design variables of offset and preload. We used the API Level-I method for a LogDec stability analysis. Following results are summarized only in a standpoint of LogDec stability. The Hybrid 3-Pad LOP TPJBs most excellently outperform all the other TPJBs over nearly a full range of cross-coupled stiffness. In a high range of cross-coupled stiffness, both the 6-Pad LOP and 5-Pad LOP TPJBs may be recommended as a practical conservative bearing design approach for enhancing a rotordynamic stability of the HPT. As expected, in a high range of cross-coupled stiffness, the 6-Pad LBP TPJBs exhibit a better performance than the 5-Pad LBP TPJBs. However, contrary to one's expectation, notably, the 5-Pad LOP TPJBs exhibit a slightly better performance than the 6-Pad LOP TPJBs. Furthermore, we do not recommend any TPJB design efforts of either increasing a pad offset from 0.5 or a pad preload from 0 for the HPT in a standpoint of stability.

주제어

표/그림 (12)

표 Table 1. Design and operation condition data of HPT TPJBs
그림 Fig. 1. Lubrication analysis geometry model of HPT 6-Pad LOP #1 TPJB for offset = 0.5 and m = 0.0.
그림 Fig. 2. A FE rotordynamic analysis model of HPT rotor with a cross-coupling element added in the middle and its 1st mode shapes in red, simultaneously, in horizontal and vertical planes at 3,600 rpm with 6-Pad LOP TPJBs: m = 0.0 and offset = 0.5, for Q_A = 1.5e + 08 N/m.
그림 Fig. 3. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 6-Pad TPJBs, depending on the LOP and LBP: m = 0.0 and offset = 0.5.
그림 Fig. 4. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 5-Pad TPJBs, depending on the LOP and LBP: m = 0.0 and offset = 0.5.
그림 Fig. 5. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with LBP TPJBs, depending on the 6-Pad and 5-Pad: m = 0.0 and offset = 0.5.
그림 Fig. 6. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with LOP TPJBs, depending on the 6-Pad and 5-Pad: m = 0.0 and offset = 0.5.
그림 Fig. 7. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 5-Pad LBP TPJBs, depending on the offset: m = 0.0 and offset = 0.5, 0.55, 0.6.
그림 Fig. 8. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 5-Pad LBP TPJBs, depending on the preload: m = 0.0, 0.2, 0.4 and offset = 0.5.
그림 Fig. 9. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 5-Pad LBP TPJBs, depending on the offset and preload, independently: m = 0.0, 0.2, 0.4 and offset = 0.5, 0.55, 0.6.
그림 Fig. 10. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with 5-Pad LBP TPJBs, depending on the offset and preload, independently (m = 0.0, 0.4 and offset = 0.5, 0.55) and simultaneously (m = 0.4 and offset = 0.6).
그림 Fig. 11. Applied LogDec characteristics, at 3,600 rpm, of the HPT rotor with various TPJBs designs in summary.

AI 본문요약
AI-Helper

제안 방법

For a HPT of 800 MW class supercritical thermalpower plant, considering aerodynamic cross-coupling induced by high-temperature and high-pressure steam, we performed a rotordynamic LogDec stability analysis with applying various TPJB designs, which several steam turbine OEMs currently use in their supercritical or ultra-supercritical turbines. We considered the following TPJB designs: 6-Pad LOP, 6-Pad LBP, 5-Pad LOP, 5- Pad LBP, Hybrid 3-Pad LOP (lower 3-Pad tilting and upper 1-Pad fixed), and 5-Pad LBPs with design variables of offset and preload.
For a HPT of 800 MW class supercritical thermalpower plant, considering aerodynamic cross-coupling induced by high-temperature and high-pressure steam, we performed a rotordynamic LogDec stability analysis with applying various TPJB designs, which several steam turbine OEMs currently use in their supercritical or ultra-supercritical turbines. We considered the following TPJB designs: 6-Pad LOP, 6-Pad LBP, 5-Pad LOP, 5- Pad LBP, Hybrid 3-Pad LOP (lower 3-Pad tilting and upper 1-Pad fixed), and 5-Pad LBPs with design variables of offset and preload.

성능/효과

Besides, in a high range of cross-coupled stiffness, both the 6- Pad LOP and 5-Pad LOP TPJBs may be recommended as well as a practical conservative bearing design approach for enhancing a rotordynamic stability of the HPT. As expected, in a high range of cross-coupled stiffness the 6-Pad LBP TPJBs exhibit a better performance than the 5-Pad LBP TPJBs. However, in contrast to one's expectation, notably, the 5-Pad LOP TPJBs exhibit a slightly better performance than the 6-Pad LOP TPJBs over a full range of cross-coupled stiffness.
The Hybrid 3-Pad LOP TPJBs most excellently outperform all the other TPJBs over nearly a full range of cross-coupled stiffness. Besides, in a high range of cross-coupled stiffness, both the 6- Pad LOP and 5-Pad LOP TPJBs may be recommended as well as a practical conservative bearing design approach for enhancing a rotordynamic stability of the HPT. As expected, in a high range of cross-coupled stiffness the 6-Pad LBP TPJBs exhibit a better performance than the 5-Pad LBP TPJBs.
For 5-Pad LBP TPJBs, the effects of offset and preload, m, which are key design variables of TPJBs, were analyzed.
Furthermore, we do not recommend any TPJBs design efforts of either increasing a pad offset from 0.5 or a pad preload from 0 for the HPT, in a standpoint of stability.
However, in contrast to one's expectation, notably, the 5-Pad LOP TPJBs exhibit a slightly better performance than the 6-Pad LOP TPJBs over a full range of cross-coupled stiffness
Following results are summarized only in a standpoint of LogDec stability. The Hybrid 3-Pad LOP TPJBs most excellently outperform all the other TPJBs over nearly a full range of cross-coupled stiffness. Besides, in a high range of cross-coupled stiffness, both the 6- Pad LOP and 5-Pad LOP TPJBs may be recommended as well as a practical conservative bearing design approach for enhancing a rotordynamic stability of the HPT.

참고문헌 (12)

Nicholas, J., "Tilting Pad Bearing Design," Proceedings of the 23rd Turbomachinery Symposium, Turbolab, Texas A&M Univ., pp.179-194, 1994.
Zeidan, F., "Fluid Film Bearings Fundamentals," Proceedings of the 1st Middle East Turbomachinery Symposium, Turbolab, Texas A&M Univ., 2011.
He, M., Byrne, J., Cloud, H, Vazquez, J., "Fundamentals of Fluid Film Journal Bearing Operating and Modeling," Proceedings of the Asia Turbomachinery & Pump Symposium, Turbolab, Texas A&M Univ., 2016.
Lee, A. S., "Design Analysis to Enhance Rotordynamic Stability of High-Speed Light-weight Centrifugal Compressor - Part I: Effects of Bearing Designs," J. Korean Soc. Tribol. Lubr. Eng., Vol. 29, No.6, pp.386-391, 2013, https://doi.org/10.9725/kstle.2013.29.6.386

원문보기 상세보기
Salamone, D., "Journal Bearing Design Types and their Applications to Turbomachinery," Proceedings of the 13th Turbomachinery Symposium, Turbolab, Texas A&M Univ., pp.179-188, 1984.
Vance, J., Zeidan, F., Murphy, B., Machinery Vibration and Rotordynamics, Chap.5, pp.171-267, John Wiley & Sons, 2010.
Nicholas, J. C., Gunter, E. J., Barrett, L. E., "The Influence of Tilting Pad Bearing Characteristics on the Stability of High Speed Rotor-Bearing Systems," Topics in Fluid Film Bearing and Rotor Bearing System Design and Optimization, ASME, pp.55-78, 1978.
Lee, A. S., "Design Analysis for Enhancing Rotordynamic Stability of High-Speed Light-weight Centrifugal Compressor - Part II: Improvement to Rotordynamic Stability," Journal of the KSTLE, Vol.30, No.1, pp.9-14, 2014, https://doi.org/10.9725/kstle.2014.30.1.9

원문보기 상세보기
Ikeno, K., Sasaki, Y., Kawabata, R., Yoshida, S., Hata, S., "Measurement of Dynamic Performance of Large Tilting Pad Journal Bearing and Rotor Stability Improvement," Proceedings of the 39th Turbomachinery Symposium, Turbolab, Texas A&M Univ., 19-29, 2010.
API STD 617 8th Ed., Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services, American Petroleum Institute, 2014.
API RP STD 684 2nd Ed., API Standard Paragraphs Rotordynamic Tutorial: Lateral Critical Speeds, Unbalance Response, Stability, Train Torsionals, and Rotor Balancing, American Petroleum Institute, 2005.
Lee, A. S., and Jang, S.-Y., "Design Characteristics of HPT Bearings in 800 MW Class Supercritical Steam Turbines Train," Proc. Spring Conf. Korean Tribol. Soc., Pusan, Korea, April, 2018.

표제어: PCR

동의어: Packet Collision Rate

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