A theoretical identification method for dynamic coefficients of seals based on infinitesimal trajectory of rotors

PDF(1481 KB)

Journal of Vibration and Shock ›› 2019, Vol. 38 ›› Issue (16) : 22-28.

GU Qianlei 1 ZHANG Wanfu 1 ZHANG Yao 1 CHEN Luqi 1 LI Chun1 YANG Jiangang2

Author information +

History +

Abstract

An identification method using the infinitesimal trajectory method was proposed to predict rotor dynamic coefficients of annular gas seals.The transient solution combined with the moving grid method was unitized to obtain the fluid force at a specific position under different whirling frequencies.The infinitesimal method was then used to obtain the rotor dynamic coefficients, which agreed well with published experimental results.Particularly, the stability parameter of the effective damping coefficient could be solved precisely.Results show that the whirling frequency has little influence on direct damping coefficient, effective damping coefficient and cross-coupling stiffness coefficient.Results also show that the fluid velocity in maximum clearances is less than that in minimum clearances.The inertial effect dominants the flow field.Then it results in higher pressure that appears in maximum clearances.The pressure differential aggravates the eccentricity of rotors and results in the static instability of the seal system.

Key words

seal / rotordynamic coefficients / computational fluid dynamics / static instability / fluid-induced vibration

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

GU Qianlei 1 ZHANG Wanfu 1 ZHANG Yao 1 CHEN Luqi 1 LI Chun1 YANG Jiangang2. A theoretical identification method for dynamic coefficients of seals based on infinitesimal trajectory of rotors[J]. Journal of Vibration and Shock, 2019, 38(16): 22-28

References

[1] Denton J D．Loss Mechanisms in Turbomachinery[J]．Journal of Turbomachinery，1993， 115：621-656．
[2] 何国安，张学延，张卫军．汽轮发电机组轴系振动研究进展及趋势[J]．热力发电，2016，45(11)：1-4．
    HE Guoan，ZHANG Xueyan，ZHANG Weijun．Research status and delelopment trends of turbo-generator shaft system vibration[J]．Thermal Power Generation，2016， 45(11)：1-4．
[3] 宋光雄，陈松平，宋君辉，等．汽轮机组汽流激振故障原因及分析[J]．动力工程学报，2012，32(10)： 770-778．
    SONG Guangxiong，GHEN Songping，SONG Junhui， et al．Cause Analysis of Steam-excited Vibration in Steam Turbine Unit[J]．Journal of Chinese Society of Power Engineering，2016(11)：1-4．
[4] 骆名文，丁学俊，祁小波，等．大型汽轮机汽流激振研究现状及展望[J]．热能动力工程，2006，21(06)： 551-555．
    LUO Mingwen，DING Xuejun，QI Xiaobo，et al．The Status Quo and Prospect Conerning a Study on Steam Flow Excitations in Large-sized Steam Turbine[J]．Journal of Engineering for Thermal Energy & Power，2006，21(06)：551-555．
[5] 荆建平，孟光，赵玫，等．超超临界汽轮机汽流激振研究现状与展望[J]．汽轮机技术，2004(06)：405-407．
    JING Jianping，MENG Guang，ZHAO Mei，et al．Survey and Outlook on the Research of the Steam Excitation of Superior Ultra-critical Steam Turbine[J]．Turbine Technology，2004(06)：405-407．
[6] Hirs G G．A bulk-flow theory for turbulence in lubrication films[J]．Journal of Lubrication Technology，1973，95(2)：137-145．
[7] Kostyuk A G．A theoretical analysis of the aerodynamic forces in the labyrinth glands of turbomachines[J]．Teploenergetica，1972，419(11)：29-33．
[8] Rhode D L．Simulation of subsonic flow through a generic labyrinth seal cavity[C]// ASME 1985 International Gas Turbine Conference and Exhibit. Houston: ASME ,1985．
[9] Stoff H．Incompressible flow in a labyrinth seal[J]．J．Fluid Mech，1980，100(4)：817-829．
[10] Scharrer J K，Nelson C C．Rotordynamic Coefficients for Partially Tapered Annular Seals：Part I — Incompressible Flow[J]．Journal of Tribology，1991， 113(1)：48-52．
[11] Childs D，Scharrer J K．An Iwatsubo-based solution for labyrinth seals：comparison to experimental results：ASME International Gas Turbine Conference， Houston，TX，18–21 March 1985，ASME paper 85-GT-136[Z]．1985．
[12] Wysmann J K，Pham T C，Jenny R J．Prediction of stiffness and damping coefficients for centrifugal compressor labyrinth seal[J]．ASME J．Eng．Gas Turbines Power，1984，106(4)：920-926．
[13] Dereli Y．Comparison of rotordynamic coefficients for labyrinth seals using a two-control volume method[J]．Proceedings of the Institution of Mechanical Engineers，Part A：Journal of Power and Energy， 2008，　222(1)：123-135．
[14] Zhou J．Analysis of leakage flow and dynamic coefficients of gas labyrinth seals using a three control volume method[D]．University of Virginia，2007．
[15] Nordmann R，Weiser P．Evaluation of rotordynamic coefficients of straight-through labyrinths by means of a three volume bulk flow model：NASA Conference Publication 3122：Rotordynamic Instability Problems in High-Performance Turbomachinery[Z]．1990．
[16] Iwatsubo T，Matooka N，Kawai R．Flow induced force and flow patterns of labyrinth seals：NASA CP 2250 Proceedings of a Workshop at Texas A&M University， Entitled Rotordynamic Instability Problems in High Performance Turbomachinery[Z]．1982．
[17] Benckert H，Wachter J．Flow induced spring coefficients of labyrinth seals for application in rotor dynamics： NASA Conference Publicaiton 2133：Rotordynamic Instability Problems in High-Performance Turbomachinery[Z]．Texas A&M University，College Station：1980．
[18] Childs D W，Scharrer J K．Experimental Rotordynamic Coefficient Results for Teeth-on-Rotor and Teeth-on-Stator Labyrinth Gas Seals[J]．Journal of Engineering for Gas Turbines and Power，1986，108(4)： 559-604．
[19] Childs D W，Scharrer J K．Theory Versus Experiment for the Rotordynamic Coefficient of Labyrinth Gas Seals：Part II — A Comparison to Experiment[J]． Journal of Vibration，Acoustics，Stress，and Reliability in Design，1988，110(3)：281-287．
[20] Dawson M P，Childs D W，Holt C G，et al．Measurements versus predictions for the dynamic impedance of annular gas seals - Part I：Test facility and apparatus[J]．Journal of Engineering for Gas Turbines and Power-Transactions of the Asme，2002，124(4)：958-962．
[21] Weatherwax M，Childs D W．Theory versus experiment for the rotordynamic characteristics of a high pressure honeycomb annular gas seal at eccentric positions[J]．Journal of Tribology-Transactions of the Asme，2003，125(2)：422-429．
[22] Tiwari R．A Review of the Experimental Estimation of the Rotor Dynamic Parameters of Seals[J]．Shock and Vibration Digest，2005，37(4)：261-284．
[23] 杨建刚，张万福，曹浩，等．密封动力特性系数试验识别方法[P]．2011年09月14日．ZL201010135887．7
    YANG Jiangang，ZHANG Wanfu，CAO Hao，et al．Experimental Identification Method for Dynamic Coefficients of Seals
[24] 曹浩，杨建刚，张万福，等．基于不平衡同频激励的密封动力特性系数识别[J]．中国电机工程学报，2011(35)：117-122．
    CAO Hao，YANG Jiangang，ZHANG Wanfu，et al．Experimental Identification Method Using Unbalance Synchronous Frequency Excitation for Seals rotordynamic Coefficients Analysis[J]．Proceedings of the CSEE，2011(35)：117-122．
[25] Mehra A．A finite volume model for calculation of leakage and hydrodynamic forces in gas seals[D]．University of Virginia，1995．
[26] Dietzen F J，Nordmann R．A three-dimensional finite difference method for calculating the dynamic coefficients of seals： NASA Conference Publicaiton 3026：Rotordynamic Instability Problems in High-Performance Turbomachinery[Z]．Texas A&M University，College Station：1988．
[27] Hirano T，Guo Zenglin，Kirk R G．Application of computational fluid dynamics analysis for rotating machinery-Part II：Labyrinth seal analysis[J]．Journal of Engineering for Gas Turbines and Power-Transactions of the ASME，2005，127(4)：820-826．
[28] Moore J J．Three-Dimensional CFD Rotordynamic Analysis of Gas Labyrinth Seals[J]．Journal of Vibration and Acoustics，2003，125(4)：427-433．
[29] Yan Xin，He Kun，Li Jun，et al．A Generalized Prediction Method for Rotordynamic Coefficients of Annular Gas Seals[J]．Journal of Engineering for Gas Turbines and Power，2015，137(9)：092506．
[30] Li J，Li Z，Feng Z．Investigations on the Rotordynamic Coefficients of Pocket Damper Seals Using the Multifrequency，One-Dimensional，Whirling Orbit Model and RANS Solutions[J]．Journal of Engineering for Gas Turbines and Power-Transactions of the ASME，2012，134(10)．102510．
[31] Li Zhigang，Li Jun，Yan Xin．Multiple Frequencies Elliptical Whirling Orbit Model and Transient RANS Solution Approach to Rotordynamic Coefficients of Annual Gas Seals Prediction[J]．Journal of Vibration and Acoustics-Transactions of the ASME，2013， 135(3)：031005．
[32] Ertas B H， Delgado A，Vannini G．Rotordynamic Force Coefficients for Three Types of Annular Gas Seals With Inlet Preswirl and High Differential Pressure Ratio[J]．Journal of Engineering for Gas Turbines and Power，2012，134(4)：042503．
[33] Picardo A，Childs D W．Rotordynamic Coefficients for a Tooth-on-Stator Labyrinth Seal at 70 bar Supply Pressures：Measurements Versus Theory and Comparisons to a Hole-Pattern Stator Seal[J]．Journal of Engineering for Gas Turbines and Power-Transactions of the Asme，2005，127(4)：843-855．
[34] Mehta N J．Comparison of a Slanted-Tooth See-Through Labyrinth Seal to a Straight-Tooth See-Through Labyrinth Seal For Rotordynamic Coefficients and Leakage[D]．Texas A&M University，2012．