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研究生:崔靜觀
研究生(外文):Ching-kuan Tsuei
論文名稱:利用線性二次調節器預防流體膜軸承中流體引發不穩定之研究
論文名稱(外文):LQR Method Used in Fluid-Induced Instability Prevention for Rotating Machinery with Fluid-Film Bearings
指導教授:潘敏俊
指導教授(外文):Min-chun Pan
學位類別:碩士
校院名稱:國立中央大學
系所名稱:機械工程研究所
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2011
畢業學年度:99
語文別:英文
論文頁數:62
中文關鍵詞:流體引發不穩定油漩油顫線性二次調節器可接受範圍
外文關鍵詞:Acceptance regionLinear quadratic regulatorWhipFluid-induced instabilityWhirl
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由於動壓軸承具有承載力強、構造簡單、成本低以及容易安裝等諸多優點,因此普遍被應用在大型轉動機械中,但是油漩與油顫這一類因動壓軸承中流體所引發之不穩定現象,卻經常困擾著工程人員。此不穩定現象主要發生在轉動機械剛啟動時,以及運轉中負載條件突然改變。油漩與油顫之處理方式有許多種,因動壓軸承中油膜的流體平均速度是引起不穩定的重要參數之一,在本研究中使用一氣壓回授裝置,當油漩發生時藉回授輸入改變流體平均速度,進而使系統穩定。通常運轉中的機械狀態改變時,系統狀態訊息會蘊藏在其振動信號中,經由分析油漩發生時的訊號得知;當油漩發生時,軸中心位置會偏離機器運轉位置,若將穩定位置設定一「可接受範圍」時,可做為適當之控制指標。此外,結合「線性二次調節器」演算法計算閉迴路系統之回授,此為一經過最佳化設計之控制回授,使用者可依其控制性能之需求,藉由調整演算法之權重來達成其設計規格;實驗結果除了展現轉動機械的不穩定可有效地被消除外,提議的「可接受範圍」方法,也可用來做為監測配備有流體膜軸承的機台在發生流體引發不穩定及摩擦時之依據。
Hydrodynamic bearings are often used in large rotating machinery because they have many advantages, such as high load capacities, simple structures, low cost and easily to be equipped etc. The fluid-induced instability, however, are usually vexing when rotating machinery, which is equipped with fluid-film bearings, are operating during start up or lightly loaded. There are several ways to cope with the fluid-induced instability. Since the fluid circumferential average velocity associated with journal speed generally is a key factor to cause the instability, therefore, in this study a method of anti-swirl injection is adopted to decrease the fluid circumferential average velocity and shift the instability to a higher operation speed.
When the operation conditions of machinery are changed, the reasons can be figured out through the analysis of the machinery vibration signal. The study uses an acceptance region with a linear quadratic regulator to address the problem of fluid-induced instability. The former is applied as a control index and the latter is employed to obtain the optimal feedback gain. Appropriate setting of an acceptance region and adequate weightings can achiveve the desired control performance easily. The experimental results show that the instability is soothed and the proposed technique using acceptance region can also be used to monitor rub and fluid-induced instability existing in this kind of rotary machinery.
摘要 I
Abstract II
誌謝 IV
Contents IV
List of Figures VI
Chapter 1 Introduction 1
1.1 Research Background and Motivation 1
1.2 Literature Review 3
1.3 Framework 5
Chapter 2 Theoretical Basis of Fluid-Film Rotor Bearing System 7
2.1 Preface 7
2.1.1 Types of Fluid-Film Bearings 7
2.1.2 Fluid Circulation 8
2.2 Rotor System Modeling 9
2.3 Self-Excited Vibration1 5
2.4 Linear Quadratic Regulator 17
Chapter 3 Experimental Setup and Test Procedure 22
3.1 Experimental Setup 22
3.1.1 Rotor Rig 22
3.1.2 DSP Board and GUI 23
3.1.3 Control Panel 25
3.2 Flow Chart for Elimination Fluid Whirl 25
chapter 4 Experimental Results and Discussions 27
4.1 Vibration Observation without Control 27
4.1.1 Result Interpretation 27
4.1.1.1 Timebase Plot 27
4.1.1.2 Orbit Plot 29
4.1.2 Transition from Stability to Instability 31
4.1.3 Use of Acceptance Region 32
4.2 Improvement on Fluid-Induced Vibration with Control 34
4.3 Concluding Remarks 44
Chapter 5 Conclusion and Future Work 45
5.1 Conclusion 45
5.2 Future Work 46
Reference 48
Appendix 1 51
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[2] Muszynska, A., 2005, “Rotordynamics,” CRC Taylor & Francis Group.
[3] Gasch, R., Nordmann, R. and Pfützner, H., 2002, “Rotordynamic,” Springer.
[4] Vance, J., 1988, “Rotordynamics of Turbomachinery,” John Wiley.
[5] Childs, D., 1993, “Turbomachinery Rotordynamics,” Wiley-Intersciences.
[6] Genta, G., 2005, “Dynamics of rotating systems,” Springer.
[7] Hearn, C., Maddox, W., Kim, Y., Gupta, V., Masser, D., Koenemant, P., Chu, C., Busch-Vishniac, I., Neikirk, D., Weldon, W. and Wood, K., “Smart mechanical bearings using MEMS technology, 1995, ” American Society of Mechanical Engineers, Petroleum Division (Publication) PD, Tribology Symposium 1995, Vol. 72, pp. 1-10.
[8] Rylander, H., Carlson, M. and Lin, C., 1995, “Actively controlled bearing surface profiles theory and experiments,” American Society of Mechanical Engineers, Petroleum Division (Publication) PD, Tribology Symposium 1995, Vol. 72, pp. 11–14.
[9] Nicoletti, R. and Santos, I.F., 2008, “Control system design for flexible rotors supported by actively lubricated bearings,” Journal of Vibration and Control, Vol. 14, pp. 347–374.
[10] Adams, M.L. and Payandeh, Y., 1983, “Self-excited vibration of statically unloaded pads in tilting-pad journal bearings,” Journal of lubrication technology, Vol. 5, pp. 377–384.
[11] Rouch, K.E., 1983, “Dynamics of pivoted-pad journal bearings including pad translation and rotation effects,” ASLE Transactions, Vol. 26, pp. 102–109.
[12] Deckler, D.C., Veillette, R.J., Braun, M.J. and Choy, F.K., 2004, “Simulation and control of an active tilting-pad journal bearing,” Tribology Transactions, Vol. 47, pp. 440–458.
[13] Cai, Z., Queiroz, M.S. and Khonsari, M.M., 2004, “On the active stabilization of tilting-pad journal bearings,” Journal of Sound and Vibration, Vol. 273, pp. 421–428.
[14] Bently, D.E. and Hatch, C.T., 2006, “Shaft levitation made simple,” Turbomachinery International, Vol. 47, pp. 30–32.
[15] Cheng, K. and Rowe, W.B., 1995, “A selection strategy for the design of externally
pressurized journal bearings,” Tribology International, Vol. 28, pp. 465–474.
[16] Muszynska, A., Franklin, W.D. and Bently, D.E., 1988, “Rotor active ‘anti-swirl’ control,” Journal of Vibration, Acoustics, Stress, and Reliability in Design, Vol. 110, pp. 143–150.
[17] Muszynska, A. and Bently, D.E., 1989, “Anti-swirl arrangements prevent rotor/seal instability,” Journal of Vibration Acoustics Stress and Reliability in Design, Vol. 111, pp. 156–162.
[18] Amati, N., Carabelli, S., Genta, G., Macchi, P., Silvagni, M. and Tonoli, A., 2006, “More electric aero engines: tradeoff between different electromagnetic dampers and supports,” Proceedings of the 10th ISMB Conference, Martigny, Switzerland pp. 21–23.
[19] Fan, C.C. and Pan, M.C., 2011, “Experimental study on the whip elimination of rotor-bearing systems with electromagnetic exciters,” Mechanism and Machine Theory, Vol. 46, pp. 290–304.
[20] Bellman, R., 1961, “Adaptive control process: A guided tour,” Princeton University Press.
[21] Bellman, R., 2008, “Bellman special issue,” IEEE Trans.Autom. Control, Vol. AC-26, Oct.
[22] Jeffrey, B., 1999, “Linear optimal control: H2 and H[infinity] methods,” Addison Wesley.
[23] Tewari, A., 2002, “Modern control design with Matlab and simulink,” John Wiley.
[24] Lewis, F., 1995, “Optimal control,” Wiley.
[25]Phillips, C., 1995, “ Digital control system analysis and design,” Prentice Hall.
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