本文選題：袋型阻尼密封　切入點：泄漏特性　出處：《西安交通大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：旋轉(zhuǎn)密封是葉輪機械中的關(guān)鍵部件,控制著通過動靜間隙從高壓區(qū)域向低壓區(qū)域的泄漏流動。雖然旋轉(zhuǎn)密封的主要功能是抑制泄漏流動,但其在控制泄漏流動的同時會產(chǎn)生流體激振力,對葉輪機械的轉(zhuǎn)子系統(tǒng)穩(wěn)定性具有顯著影響。相比于傳統(tǒng)的迷宮密封,袋型阻尼密封具有與之相近的密封性能和非常優(yōu)越的抑制轉(zhuǎn)子振動的能力,目前被應(yīng)用于多級高轉(zhuǎn)速離心壓氣機中,替代迷宮密封達(dá)到控制泄漏和改善轉(zhuǎn)子系統(tǒng)穩(wěn)定性的目的。本文的主要目的是通過對袋型阻尼密封泄漏特性和轉(zhuǎn)子動力特性的深入研究,闡明其密封和阻尼機理。首先,針對高參數(shù)葉輪機械中旋轉(zhuǎn)密封有效間隙會在高轉(zhuǎn)速作用下偏離其設(shè)計值的問題,率先提出了適用于袋型阻尼密封在高轉(zhuǎn)速下、考慮流固耦合效應(yīng)時的泄漏特性研究的有限元分析(FEA)和計算流體動力學(xué)(CFD)相耦合的數(shù)值方法(FEA/CFD),系統(tǒng)分析了運行工況和幾何參數(shù)對袋型阻尼密封泄漏特性的影響,得出了相應(yīng)的泄漏特性曲線。計算了典型袋型阻尼密封實驗件在3種轉(zhuǎn)速、3種壓降下的泄漏量,數(shù)值結(jié)果與實驗值吻合良好,驗證了FEA/CFD數(shù)值方法的準(zhǔn)確性和有效性。在此基礎(chǔ)上,研究了壓比、密封間隙和轉(zhuǎn)速對袋型阻尼密封泄漏特性的影響規(guī)律,并與傳統(tǒng)迷宮密封進(jìn)行了比較。研究結(jié)果表明:高轉(zhuǎn)速下,采用FEA數(shù)值方法考慮轉(zhuǎn)子半徑伸長的影響能夠顯著提高密封泄漏量的預(yù)測精度;相比于壓比和轉(zhuǎn)速,密封間隙對泄漏量的影響更為顯著,周向擋板對泄漏量幾乎沒有影響;袋型阻尼密封泄漏量隨壓比的減小而增大,并逐漸趨于臨界狀態(tài)對應(yīng)的最大值;高轉(zhuǎn)速對泄漏特性的影響可分為兩個方面:粘性耗散效應(yīng)和幾何效應(yīng);袋型阻尼密封的周向擋板結(jié)構(gòu)能夠顯著地減小密封腔室內(nèi)的周向旋流速度。其次,發(fā)展了一種基于Bulk Flow理論的適用于袋型阻尼密封轉(zhuǎn)子動力特性系數(shù)預(yù)測的理想氣體單控制體等溫Bulk Flow計算模型和數(shù)值算法,并開發(fā)了具有自主知識產(chǎn)權(quán)的計算程序。計算了4種典型袋型阻尼密封實驗件的頻率相關(guān)的轉(zhuǎn)子動力特性系數(shù),預(yù)測結(jié)果與實驗值吻合良好,驗證了所發(fā)展的Bulk Flow計算模型和數(shù)值算法的有效性。選用目前常用的8種迷宮密封泄漏量預(yù)測模型,分析了泄漏量預(yù)測模型對所發(fā)展的Bulk Flow模型預(yù)測精度的影響,選出了最優(yōu)的泄漏模型。在此基礎(chǔ)上,研究了密封齒數(shù)、密封間隙、密封間隙比和腔室深度等幾何設(shè)計參數(shù)對袋型阻尼密封轉(zhuǎn)子動力特性的影響。結(jié)果表明:袋型阻尼密封的密封齒數(shù)和腔室深度均存在一個最優(yōu)值使其具有最大的阻尼;較小的密封間隙對提高袋型阻尼密封的阻尼是有利的。再著,首次提出了預(yù)測旋轉(zhuǎn)密封轉(zhuǎn)子動力特性的多頻渦動模型和非定常CFD數(shù)值方法,包括轉(zhuǎn)子多頻渦動位移的三種數(shù)學(xué)模型(直線渦動軌跡模型、圓渦動軌跡模型和橢圓渦動軌跡模型)、非定常流體激振力的CFD求解方法和轉(zhuǎn)子動力特性系數(shù)的頻域提取方法。基于多頻橢圓渦動模型,計算分析了三種典型的旋轉(zhuǎn)密封實驗件(迷宮密封、袋型阻尼密封和孔型密封)在不同轉(zhuǎn)速、進(jìn)口預(yù)旋條件下、20~300Hz頻率范圍內(nèi)的頻率相關(guān)的轉(zhuǎn)子動力特性系數(shù),三種旋轉(zhuǎn)密封的預(yù)測結(jié)果均與實驗值吻合良好,驗證了所提出的多頻渦動模型和CFD數(shù)值方法的準(zhǔn)確性和適用性。分析了多頻渦動位移數(shù)學(xué)模型和湍流模型對預(yù)測結(jié)果的影響。研究結(jié)果表明:多頻渦動模型只需進(jìn)行一次非定常求解便可獲得多個頻率下的轉(zhuǎn)子動力特性系數(shù),具有預(yù)測精度高、計算速度快和對不同的旋轉(zhuǎn)密封結(jié)構(gòu)普遍適用的優(yōu)點;多頻渦動模型的預(yù)測結(jié)果不受轉(zhuǎn)子渦動軌跡的影響;從預(yù)測精度和計算時間兩個方面綜合考慮,在旋轉(zhuǎn)密封轉(zhuǎn)子動力特性系數(shù)的數(shù)值預(yù)測中,標(biāo)準(zhǔn)k-?湍流模型是一種經(jīng)濟適用的湍流模型。最后,采用所提出的多頻橢圓渦動模型和非定常CFD數(shù)值方法,系統(tǒng)全面地評估了運行工況(壓比、轉(zhuǎn)速、進(jìn)口預(yù)旋)和幾何結(jié)構(gòu)參數(shù)(周向擋板數(shù)、腔室深度)對袋型阻尼密封轉(zhuǎn)子動力特性的影響規(guī)律。研究結(jié)果表明:相比于密封出口壓力,密封進(jìn)口壓力對袋型阻尼密封轉(zhuǎn)子動力特性的影響更為顯著;袋型阻尼密封的有效阻尼隨進(jìn)口壓力的增大而顯著增大;袋型阻尼密封更適宜安裝在進(jìn)口壓力高,進(jìn)出口壓差大的位置。轉(zhuǎn)速和進(jìn)口預(yù)旋均使袋型阻尼密封的交叉剛度絕對值明顯增大,使有效阻尼系數(shù)顯著減小,其中進(jìn)口預(yù)旋的影響更為顯著。相比于迷宮密封,袋型阻尼密封能夠提供更大的頻率相關(guān)的直接剛度和直接阻尼;增加袋型阻尼密封的周向擋板數(shù)能顯著地增大直接剛度,但對有效阻尼的增大效果有限。相比于直通光滑環(huán)形密封,袋型阻尼密封具有較大的直接剛度和較小的有效阻尼;袋型阻尼密封的腔室深度存在一個最優(yōu)值使其同時具有較大的直接剛度和較大的有效阻尼。本文針對袋型阻尼密封在高轉(zhuǎn)速下的非定常泄漏流動和轉(zhuǎn)子動力特性開展了深入的數(shù)值研究。所提出的FEA/CFD耦合的泄漏特性數(shù)值分析方法、Bulk Flow分析模型和基于多頻渦動模型的轉(zhuǎn)子動力特性數(shù)值預(yù)測方法為進(jìn)一步提高葉輪機械運行效率和穩(wěn)定性的高性能袋型阻尼密封設(shè)計提供了理論基礎(chǔ)和技術(shù)支撐。
[Abstract]:The rotary sealing is a key component in turbomachinery, controlled by clearance from the high pressure to low pressure leakage flow. Although the main function of rotating seal leakage flow is suppressed, but at the same time, the leakage flow in the control will produce fluid exciting force, has a significant impact on the stability of rotor system of turbine machinery. Compared to the the traditional labyrinth seal, pocket damper seal ability has the similar sealing performance and excellent suppression of rotor vibration, has been used in high speed multistage centrifugal compressor, instead of labyrinth seal to control leakage and improve the stability of the rotor system. The main purpose of this paper is through in-depth study of the characteristics and the seal leakage the rotor dynamic characteristics of the pocket damper, the sealing and damping mechanism. Firstly, aiming at the high mechanical parameters of the impeller rotating seal in effective clearance at The design value of the deviation from the high speed under the action, first proposed for pocket damper seal at high speed, the finite element analysis of the leakage of the fluid solid coupling effect considered (FEA) and computational fluid dynamics (CFD) numerical method of coupled system (FEA/CFD), analyzes the influence of operating conditions geometrical parameters and characteristics of the pocket damper seal leakage, leakage characteristic curves are obtained. The experiment in 3 kinds of sealing speed typical pocket damper was calculated, the 3 pressure drop under the leakage, numerical results are in good agreement with experimental results, verify the accuracy of the FEA/CFD value and the effectiveness of the method. On the basis of on the study of the ratio of pressure, the sealing effect of clearance and speed of the pocket damper seal leakage characteristics, and compared with the traditional labyrinth seal. The results show that the high speed, considering the rotor radius extension using FEA numerical method Long effect can significantly improve the prediction accuracy of leakage; compared to the pressure ratio and rotational speed, the sealing effect of the clearance on the leakage is more significant, the peripheral barrier has almost no effect on the leakage; leakage increases with the decrease of pressure ratio of pocket damper seal, the maximum value and gradually to the critical state of the corresponding high speed; influence on the leakage characteristics can be divided into two aspects: the viscous dissipation effect and geometric effect; pocket damper seal circumferential baffle structure can significantly reduce the sealing chamber circumferential flow. Secondly, the development of an ideal gas for Bulk Flow based on the theory of dynamic in pocket damper seal the prediction coefficients of rotor single control volume isothermal Bulk Flow calculation model and numerical algorithm, a computer program is developed with independent intellectual property rights. The calculated frequency of 4 typical experimental pieces of pocket damper seal The rotor dynamic coefficients, the prediction results in good agreement with experimental results, verify the effectiveness of the development of the Bulk Flow calculation model and numerical algorithm. The 8 kinds of commonly used labyrinth seal leakage prediction model, analyzes the leakage prediction model on the impact of Bulk Flow model development, selected leakage the best model. On this basis, the effect of sealing tooth number, seal clearance, seal clearance ratio and chamber depth geometric design parameters of the pocket damper seal rotor dynamic characteristics. The results show that the pocket damper seal teeth and chamber depth has an optimal value so that it has the maximum damping the smaller; the seal gap is favorable to improving the pocket damper seal damping. Then, for the first time put forward a prediction of multi frequency eddy rotary seal dynamic characteristics of rotor dynamic model and unsteady numerical method CFD, The rotor includes three kinds of mathematical models of multi frequency eddy displacement (the linear eddy trajectory model, circular whirl orbit model and elliptic vortex trajectory model), frequency domain from the unsteady fluid force CFD method and rotor dynamic characteristic coefficient method. A multi frequency elliptical vortex model based on calculation and analysis three typical rotary seal test (labyrinth seal, pocket damper seal and seal groove) at different rotational speed, inlet swirl, the frequency range of 20~300Hz frequency dependent rotordynamic coefficient, the three prediction results of rotating seal in good agreement with experimental results, verify the accuracy of the model and CFD the numerical method of multi frequency eddy and the applicability of the proposed analysis. The multi frequency eddy displacement mathematical model and turbulence model on the prediction results. The results show that the multi frequency eddy model only one unsteady solution will Can obtain the rotordynamic coefficients at multiple frequencies, with high accuracy and fast calculation speed of different rotary sealing structure has the advantages of universal application; effect of multi frequency eddy model prediction results are not affected by the rotor whirl orbit; considered from the two aspects of prediction accuracy and computation time, standard in k- numerical prediction of rotary seal rotordynamic coefficients in? Turbulence model is a turbulent economic applicable model. Finally, a multi frequency elliptical vortex with the proposed dynamic model and unsteady CFD numerical method, system and comprehensive assessment of the operating conditions (pressure ratio, rotational speed, inlet swirl) and geometric structure the parameters (circumferential baffle number, cavity depth) influence of rotor dynamic characteristics of the pocket damper seal. The results show that: compared to the seal sealing the inlet pressure outlet pressure, rotor dynamic characteristics of pocket damper seal more Significant; effective damping pocket damper seal with the increase of the inlet pressure increases significantly; pocket damper seal is more suitable for installation in the inlet pressure, outlet pressure difference large position. Increased cross speed and inlet pre swirl the pocket damper seal stiffness of the absolute value of the effective damping coefficient decreased significantly among them, the influence of inlet pre swirl is more significant. Compared to the labyrinth seal, pocket damper seal can provide more direct frequency dependent stiffness and damping directly; increase the pocket damper seal circumferential baffle number can obviously increase the stiffness, but the effective damping is increased compared to the limited effect. Through the smooth annular seal pocket damper seal effective damping has greater direct stiffness and smaller; the chamber depth of the pocket damper seal has an optimal value so that it also has a larger direct stiffness and more effective Damping. In this paper the pocket damper seal in high speed under the unsteady leakage flow and rotor dynamic characteristics was carried out extensive numerical simulations. Numerical analysis method of leakage characteristics of FEA/CFD coupling of the proposed Bulk Flow model and rotor dynamic characteristics numerical prediction method of multi frequency eddy model based on seal design the theoretical basis and technical support to further improve the performance of high damping bag type impeller mechanical efficiency and stability.

【學(xué)位授予單位】：西安交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TH136
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本文編號：1637293