本文選題：離心式壓縮機 + 轉(zhuǎn)子系統(tǒng)��； 參考：《東北大學(xué)》2012年碩士論文

【摘要】：轉(zhuǎn)子系統(tǒng)是離心壓縮機的核心部件,其性能的好壞對整個壓縮機安全可靠運行至關(guān)重要。離心壓縮機轉(zhuǎn)子系統(tǒng)的強度校核和可靠性計算越來越受到重視,已經(jīng)成為壓縮機設(shè)計中的重要一環(huán)。但傳統(tǒng)上,研究人員只注重轉(zhuǎn)子系統(tǒng)離心載荷的計算,對氣動載荷的重視程度明顯不足。隨著化工行業(yè)的快速發(fā)展,離心壓縮機進口流量不斷增大,氣動激振力對轉(zhuǎn)子系統(tǒng)的影響也越來越大,其對轉(zhuǎn)子系統(tǒng)強度的削弱作用日趨明顯。因此,在對轉(zhuǎn)子系統(tǒng)進行結(jié)構(gòu)分析的過程中,單純的由離心力導(dǎo)致的靜應(yīng)力分析已不能滿足可靠性要求。 本文依托973課題的研究背景,以制氧系統(tǒng)中的離心壓縮機為研究對象,借助有限元方法和CFD數(shù)值模擬技術(shù)研究離心壓縮機轉(zhuǎn)子系統(tǒng)性能,分析了轉(zhuǎn)子系統(tǒng)的關(guān)鍵零件的靜強度和動強度,計算出轉(zhuǎn)子系統(tǒng)葉輪內(nèi)部氣體的流動規(guī)律,近而分析出壓縮機工作過程中的氣動載荷對系統(tǒng)的影響。主要完成如下幾個研究內(nèi)容。 (1)利用大型有限元分析軟件ANSYS分別對半開式和閉式離心壓縮機計算,得出了葉片的前六階固有頻率。分別對葉輪和葉片的靜強度和動強度特性進行了分析。通過分析發(fā)現(xiàn)：在給定模型中,無論是半開式離心壓縮機葉輪,還是閉式離心壓縮機葉輪,其葉片的動強度設(shè)計比較合理,可靠性很高。而葉輪由于自振頻率比較低,容易與高頻激振力發(fā)生倍頻共振,因此,建議修改導(dǎo)葉個數(shù)改變激振力頻率或者通過其他措施改變?nèi)~輪的固有頻率,使高頻激振力頻率與葉輪固有頻率的倍頻滿足15%的避開率,以免葉輪出現(xiàn)倍頻共振,發(fā)生屈服性破壞。 (2)通過CFD軟件分別對半開式、閉式葉輪流場進行模擬計算與性能預(yù)測,分別計算出半開式、閉式葉輪和葉片不同工作情況下的受力、變形及流場分布情況,為后續(xù)計算和分析整個轉(zhuǎn)子系統(tǒng)氣動載荷做必要準(zhǔn)備。分別討論了葉片只受氣動載荷、只受離心力載荷、同時受氣動載荷和離心力載荷三種載荷情況。計算結(jié)果表明：葉片的應(yīng)力分布和總體變形趨勢在三種情況下是相似的；半開式葉輪流場的最大氣流速度出現(xiàn)在流場入口處和出口處,而非中間部位,整體上呈現(xiàn)從入口到出口逐漸增大趨勢,并且流場平均速度隨著氣體質(zhì)量流速率的增大而增大。對于閉式葉輪,在葉輪轉(zhuǎn)速不變的情況下,增加氣體質(zhì)量流率,葉輪內(nèi)部流場邊界壓力隨之增加；葉輪氣體質(zhì)量流率不變,增大葉輪轉(zhuǎn)速,葉輪內(nèi)部流場邊界壓力基本不變；另外,流場邊界壓力呈現(xiàn)由入口向出口逐漸增大的規(guī)律。 (3)對離心壓縮機的低壓轉(zhuǎn)子系統(tǒng)主軸進行了模態(tài)分析,計算了前六階固有頻率；對整個轉(zhuǎn)子系統(tǒng)不同工作情況下的氣動載荷進行仿真分析,計算出轉(zhuǎn)子系統(tǒng)在不同氣動載荷作用下受力和變形情況,分析了氣動載荷對轉(zhuǎn)子系統(tǒng)的影響。通過分析發(fā)現(xiàn)：氣動載荷下轉(zhuǎn)子系統(tǒng)主軸的應(yīng)力和變形都比較小,表明氣動載荷對主軸或軸承造成傷害不是氣動載荷產(chǎn)生的絕對應(yīng)力和變形值引起的,而是氣動載荷的交變作用造成主軸或軸承的疲勞破壞。
[Abstract]:The rotor system is the core component of the centrifugal compressor. Its performance is very important for the safe and reliable operation of the compressor. The strength checking and reliability calculation of the rotor system of the centrifugal compressor have been paid more and more attention, and it has become an important part of the compressor design. However, the researchers have traditionally paid attention to the centrifugal load of the rotor system. With the rapid development of the chemical industry, the inlet flow of the centrifugal compressor is increasing, and the effect of the aerodynamic force on the rotor system is becoming more and more, and its effect on the strength of the rotor system becomes more and more obvious. So, in the process of structural analysis of the rotor system, the simple The static stress analysis caused by centrifugal force can no longer meet the reliability requirements.
Based on the research background of the 973 subject, this paper takes the centrifugal compressor in the oxygen making system as the research object. Using the finite element method and the CFD numerical simulation technology to study the performance of the rotor system of the centrifugal compressor, the static strength and the dynamic strength of the key parts of the rotor system are analyzed, and the flow law of the internal gas in the impeller of the rotor system is calculated. The influence of the aerodynamic load on the system during the working process of the compressor is separated. The following research contents are mainly completed.
(1) using the large finite element analysis software ANSYS to calculate the semi open and closed centrifugal compressors respectively, the first six order natural frequencies of the blades are obtained. The static strength and dynamic strength characteristics of the impeller and blade are analyzed respectively. The analysis shows that in the given model, the impeller of the semi open centrifugal compressor and the closed centrifugal centrifugal compressor are found in the given model. The dynamic strength of the compressor impeller is reasonable and the reliability is very high, and the impeller is easily resonate with the high frequency excitation force because of the low frequency of self vibration. Therefore, it is suggested to modify the number of the guide vane to change the frequency of the exciting force or to change the inherent frequency of the impeller through other measures, so that the frequency of the high frequency excitation force and the inherent frequency of the impeller can be changed. The frequency doubling of the rate satisfies the avoidance rate of 15%, so as to avoid the frequency doubling resonance and yielding failure of the impeller.
(2) through the CFD software, the simulation calculation and performance prediction of the semi open and closed impeller flow field are carried out respectively. The force, deformation and flow field distribution of the semi open, closed impeller and blade are calculated respectively, and the necessary preparation for the subsequent calculation and analysis of the aerodynamic load of the whole rotor system is made. The load is only subjected to the centrifugal load, and it is subjected to three loads of the aerodynamic load and the centrifugal force. The calculation results show that the stress distribution and the overall deformation trend of the blade are similar in three cases. The maximum airflow velocity of the semi open impeller flow field appears at the entrance and exit of the flow field, not the middle part. The entrance to exit is gradually increasing, and the average velocity of the flow field increases with the increase of gas mass flow rate. For the closed impeller, the flow boundary pressure in the impeller increases with the increase of the gas mass flow rate when the impeller speed is constant, and the mass flow rate of the impeller is constant, the impeller speed is increased, and the flow field inside the impeller is on the edge. The boundary pressure basically remains unchanged, and the boundary pressure of the flow field increases gradually from the inlet to the outlet.
(3) the modal analysis of the spindle of the low pressure rotor system of the centrifugal compressor is carried out and the first six natural frequencies are calculated. The aerodynamic load of the whole rotor system under different working conditions is simulated and analyzed. The force and deformation of the rotor system under different aerodynamic loads are calculated, and the influence of the aerodynamic load on the rotor system is analyzed. Through the analysis, it is found that the stress and deformation of the spindle of the rotor system are relatively small, which indicates that the damage caused by the aerodynamic load on the spindle or bearing is not caused by the absolute stress and deformation value produced by the aerodynamic load, but the fatigue damage of the spindle or bearing caused by the alternating action of the aerodynamic load.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH45

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本文編號：1969890