本文選題：穩(wěn)定性 + 氣膜振蕩　； 參考：《中國科學院研究生院（工程熱物理研究所）》2014年博士論文

【摘要】：氣體軸承支承的高速渦輪軸系具有結構緊湊、軸承功耗低、轉速高、功率密度大等優(yōu)點,廣泛應用于空氣制冷機、高速永磁電機、微型燃氣輪機等高速微型動力設備中。高轉速下軸承非線性氣膜力引起的氣膜振蕩是影響軸承-轉子系統(tǒng)穩(wěn)定性的關鍵問題之一。本文重點開展氣體軸承-轉子系統(tǒng)穩(wěn)定分析與實驗研究,主要工作內容如下： 1.對氣體軸承-轉子系統(tǒng)穩(wěn)定性進行定性分析。提出了包含旋轉慣性項、軸頸渦動項、軸頸擠壓項以及軸承供給壓力項在內的有限長氣膜力分析模型,以軸頸偏心率為函數給出工程穩(wěn)定性判別準則及其推論,當ε≤εmax,且dε/dt≤0時,軸承-轉子系統(tǒng)在工程上是可以穩(wěn)定運行的；轉子的偏心率在某轉速點滿足ε≤εmax,且偏心率對轉速的導數小于0(即dε/dω≤0),作為轉子繼續(xù)升速的判據。并根據工程穩(wěn)定性判別準則,從設計階段和在線調整階段,給出了提高軸承-轉子系統(tǒng)穩(wěn)定性的措施和方法。 2.提出了基于圖譜分析的轉子非線性振動行為分析方法。以氣膜振蕩起始點為界,選用不同的圖譜來分析氣膜振蕩前后的動力學特征,給出了氣膜振蕩發(fā)生前不平衡量引起同頻渦動的分析圖譜和氣膜振蕩發(fā)生后氣膜非線性引起低頻渦動與振蕩的分析圖譜,并在實驗中驗證了非線性振動行為分析方法的有效性和合理性。 3.搭建高速氣體軸承-轉子系統(tǒng)實驗臺。完成動力單元、實驗臺本體、振動測試單元以及遠程監(jiān)控單元的設計與搭建工作,其軸系設計轉速在60000rpm；實驗臺能夠呈現氣膜渦動與振蕩等非線性振動現象,實現了軸承氣參數可控、可測量,轉子的振動數據可在線監(jiān)測、離線存儲與分析,并實現實驗現場的遠程監(jiān)控。 4.開展氣膜約束狀態(tài)下轉子模態(tài)實驗分析。制定模態(tài)實驗方案,從激勵的選取,測點布置方案的選取,激勵與響應信號特征分析以及頻響函數估計與評價幾個方面論述模態(tài)實驗過程,實驗結果表明：設計轉速內,轉子平動、錐動、一階彎曲固有頻率隨供氣壓力的增加而增加,且設計轉速避開轉子一階彎曲和二階彎曲臨界轉速值在合理裕度以上。模態(tài)實驗結果為軸系升降速實驗控制方案的制定,以及后續(xù)低頻振動特性分析,提供基礎性數據支撐。 5.開展轉速、軸承供氣壓力、金屬橡膠對軸承-轉子系統(tǒng)穩(wěn)定性影響的實驗研究。采用非線性振動行為分析方法,重點分析分岔點、分岔點前和分岔點后轉子動力學行為特征,結果表明：隨著轉速的增加,氣體軸承-轉子系統(tǒng)發(fā)生氣膜振蕩,發(fā)生氣膜振蕩的工頻轉速在兩倍于平動臨界轉速以上；合理的軸承供氣壓力能夠推遲分岔點,即氣膜振蕩的起始點,進而提高軸系穩(wěn)定運行的裕度；金屬橡膠墊能夠起到進一步推遲氣膜振蕩起始點的作用,同時降低軸系平動、錐動、一階彎曲臨界轉速值及相應的振動幅值,提高軸系穩(wěn)定性。 6.將穩(wěn)定調整措施在氣體軸承支承的高速微型動力設備中進行工程應用驗證。實驗結果驗證了基于圖譜分析的非線性振動行為分析方法以及工程穩(wěn)定判別準則的合理性和實用性。
[Abstract]:The high speed turbine shaft bearing supported by gas bearing has the advantages of compact structure, low bearing power, high speed and high power density. It is widely used in high speed micro power equipment, such as air chiller, high speed permanent magnet motor, micro gas turbine and so on. The air film oscillation caused by the nonlinear gas film force of bearing at high speed is the stability of bearing rotor system stability. One of the key problems of this paper is the stability analysis and experimental research of gas bearing rotor system. The main contents are as follows:
1. the stability of the rotor bearing rotor system is qualitatively analyzed. A finite length gas film force analysis model including the rotating inertia item, the journal journal vortex term, the axial neck extrusion term and the bearing pressure term is presented. The criterion for the stability of the engineering stability and its inference is given by the eccentric ratio of the journal. When the epsilon < max, and D E /dt < 0, the bearing - The rotor system can operate stably in engineering, the eccentricity of the rotor is satisfied at an epsilon of less than max at a rotational speed point, and the derivative of the eccentricity is less than 0 (d e /d Omega < 0), which is the criterion for the rotor to continue to rise. And the bearing rotor system is raised from the design stage and the on-line adjustment stage according to the criterion of the stability of the engineering. Measures and methods for stability.
2. the analysis method of nonlinear vibration behavior of rotor based on the map analysis is proposed. Taking the starting point of the gas film oscillation as the boundary, different atlas are used to analyze the dynamic characteristics before and after the air film oscillation, and the analysis Atlas of the same frequency eddy caused by the unbalance of the film before the occurrence of the gas film oscillation and the low-frequency eddy caused by the film nonlinearity after the gas film oscillation occurred after the gas film oscillation occurred. The dynamic and oscillatory analysis atlas, and verify the validity and rationality of the nonlinear vibration behavior analysis method in the experiment.
3. build a high speed gas bearing rotor system experiment platform, complete the design and construction of the dynamic unit, the experiment platform body, the vibration test unit and the remote monitoring unit. The axis design speed is 60000rpm, the experimental platform can present the nonlinear vibration of the air film vortex and oscillation and so on. The bearing gas parameters can be controlled, measurable and rotating. The vibration data of the child can be monitored online, offline stored and analyzed, and the remote monitoring of the experimental site can be realized.
4. the modal experiment analysis of the rotor under the condition of gas film constraint is carried out. The modal experiment scheme is formulated. The experimental process is discussed from several aspects: the selection of the excitation, the selection of the layout scheme of the measurement point, the characteristic analysis of the excitation and response signal and the estimation and evaluation of the frequency response function. The experimental results show that the rotor is moving, coning, and first order bending within the design speed. The natural frequency increases with the increase of gas supply pressure, and the design speed avoids the first order bending of the rotor and the two order bending critical speed above the reasonable margin. The experimental results of the modal experiment provide the basic data support for the formulation of the experimental control scheme of the shaft system and the following low frequency vibration characteristics.
5. to carry out the experimental study on the influence of the rotating speed, bearing pressure and metal rubber on the stability of the bearing rotor system. The nonlinear vibration behavior analysis method is used to analyze the bifurcation point, the bifurcation point and the dynamic behavior of the rotor after the bifurcation point. The results show that the gas bearing rotor system has gas film oscillation with the increase of the speed. The frequency speed of the gas film oscillation is more than two times that of the translation critical speed, and the reasonable bearing pressure of the bearing can postpone the bifurcation point, that is, the starting point of the gas film oscillation, and then improve the margin of the stable operation of the shaft system; the metal rubber pad can play a further role in postponing the starting point of the air film oscillation, and reduce the axis translation and cone movement. The critical speed and the corresponding vibration amplitude of the step can improve the stability of the shafting.
6. the stability adjustment measures are used to verify the engineering application of the high speed micro power equipment supported by gas bearings. The experimental results verify the rationality and practicability of the nonlinear vibration behavior analysis method based on the map analysis and the stability criterion of the engineering.

【學位授予單位】：中國科學院研究生院（工程熱物理研究所）
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TH113.25;TH133.3

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