【摘要】：泵在氣液兩相流條件下運(yùn)行的現(xiàn)象經(jīng)常會(huì)出現(xiàn)在工程實(shí)際中,而工作介質(zhì)中的氣體的存在對(duì)離心泵性能影響比較明顯,氣液兩相流條件下離心泵運(yùn)行特性會(huì)發(fā)生較大的改變,且會(huì)產(chǎn)生劇烈的振動(dòng)現(xiàn)象,嚴(yán)重時(shí)發(fā)生喘振從而影響系統(tǒng)的可靠運(yùn)行。因此,開(kāi)展氣液兩相流條件下離心泵內(nèi)部流動(dòng)機(jī)理及流動(dòng)誘導(dǎo)特性研究具有重大的理論意義和工程應(yīng)用價(jià)值。本文通過(guò)試驗(yàn)測(cè)試和數(shù)值計(jì)算相結(jié)合,基于已有的研究基礎(chǔ)和流動(dòng)理論分析開(kāi)展研究,進(jìn)行了不同轉(zhuǎn)速不同含氣率下模型泵的外特性試驗(yàn)以及壓力脈動(dòng)、振動(dòng)等動(dòng)態(tài)性能試驗(yàn),并且基于歐拉非均相流模型對(duì)模型泵在氣液兩相流動(dòng)狀態(tài)下的內(nèi)部流場(chǎng)進(jìn)行定常和非定常數(shù)值計(jì)算,主要研究?jī)?nèi)容及成果如下:1.從基礎(chǔ)理論研究、試驗(yàn)研究以及數(shù)值研究三方面分析了國(guó)內(nèi)外泵內(nèi)氣液兩相流動(dòng)的研究現(xiàn)狀,并進(jìn)行總結(jié)提出了不足,闡述了進(jìn)行氣液兩相條件時(shí)泵內(nèi)部流動(dòng)特性研究的意義。2.搭建了離心泵氣液兩相測(cè)試試驗(yàn)臺(tái),進(jìn)行了不同轉(zhuǎn)速、不同含氣率條件下的外特性試驗(yàn),得出如下結(jié)論:氣液兩相條件時(shí),在小流量工況時(shí)(φ㩳0.04),進(jìn)口含氣率超過(guò)1%性能就會(huì)急劇下降,而且運(yùn)行工況范圍會(huì)隨著進(jìn)口含氣率增大逐漸減小;在進(jìn)口含氣率低于8%時(shí),理論揚(yáng)程與所輸送流體介質(zhì)密度無(wú)關(guān);進(jìn)口含氣率低于3%時(shí)發(fā)現(xiàn)轉(zhuǎn)速相似定律依然能夠成立。3.采用LMS測(cè)試系統(tǒng),在不同進(jìn)口含氣率條件下對(duì)模型泵進(jìn)行動(dòng)態(tài)性能試驗(yàn),獲得了不同運(yùn)行工況條件下出口壓力脈動(dòng)及振動(dòng)頻譜特性,得出如下結(jié)論:壓力信號(hào)和振動(dòng)信號(hào)均服從正態(tài)分布;當(dāng)進(jìn)口含氣率超過(guò)5%時(shí),發(fā)現(xiàn)低頻區(qū)壓力脈動(dòng)幅值明顯增大;振動(dòng)信號(hào)的整體幅值會(huì)隨著含氣率的增大明顯增大,尤其是在低頻段區(qū)域,隨著含氣率逐漸增大,振動(dòng)呈先減小后增大再減小的趨勢(shì),在進(jìn)口含氣率5%時(shí)振動(dòng)最大,進(jìn)口含氣率超過(guò)5%后,低頻區(qū)振動(dòng)能量也會(huì)成為泵系統(tǒng)振動(dòng)能量重要組成部分。4.基于歐拉非均相流模型,在不同流量、不同進(jìn)口含氣率工況下對(duì)模型泵進(jìn)行定常和非定常數(shù)值計(jì)算,得出如下結(jié)論:在進(jìn)口含氣率超過(guò)3%后,初始?xì)馀葜睆绞怯?jì)算時(shí)需要考慮的重要因素;隨著含氣率的增大,氣體有沿著吸力面向出口邊運(yùn)動(dòng)的趨勢(shì),氣體可以一定程度上改善葉輪進(jìn)口回流現(xiàn)象,氣體在葉輪內(nèi)的聚集與漩渦的產(chǎn)生有關(guān);進(jìn)口含氣率達(dá)到3%時(shí),低頻區(qū)幅值會(huì)出現(xiàn)小幅的增大,產(chǎn)生寬頻脈動(dòng),而且低頻區(qū)寬頻脈動(dòng)的范圍會(huì)隨著含氣率的增大而變寬,含氣率越高對(duì)低頻寬頻脈動(dòng)的影響越明顯。
[Abstract]:The phenomenon of pump running under the condition of gas-liquid two-phase flow often appears in engineering practice, but the existence of gas in working medium has obvious influence on the performance of centrifugal pump, and the operation characteristics of centrifugal pump will be changed greatly under the condition of gas-liquid two-phase flow. Violent vibration will occur and surge will occur in severe cases, which will affect the reliable operation of the system. Therefore, it is of great theoretical significance and engineering application value to study the flow mechanism and flow induction characteristics of centrifugal pump under the condition of gas-liquid two-phase flow. In this paper, through the combination of test and numerical calculation, based on the existing research foundation and flow theory analysis, the external characteristic test of the model pump with different rotational speed and different gas content, the dynamic performance test of pressure pulsation and vibration are carried out. Based on the Eulerian heterogeneous flow model, the steady and unsteady numerical calculation of the internal flow field of the model pump in the gas-liquid two-phase flow state is carried out. The main research contents and results are as follows: 1. The present research situation of gas-liquid two-phase flow in pumps at home and abroad is analyzed from three aspects: basic theoretical research, experimental study and numerical study, and the deficiencies are summarized and put forward. The significance of the study on the flow characteristics of pumps under gas-liquid two-phase conditions is expounded. In this paper, the gas-liquid two-phase test rig of centrifugal pump is built, and the external characteristic test under different rotating speed and different gas content is carried out. The conclusion is as follows: when gas-liquid two-phase condition, When the flow rate is small (蠁 0.04), the performance of the inlet gas content will decrease sharply when the inlet gas content exceeds 1%, and the operating condition range will gradually decrease with the increase of the inlet gas content, and when the inlet gas content is lower than 8, the theoretical head will have nothing to do with the density of the fluid. When the imported gas content is lower than 3, it is found that the law of speed similarity still holds. 3. The dynamic performance of the model pump was tested with LMS test system under different inlet gas content. The characteristics of outlet pressure pulsation and vibration spectrum were obtained under different operating conditions. The conclusions are as follows: the pressure signal and vibration signal are obeyed to normal distribution; when the inlet gas content exceeds 5, it is found that the amplitude of pressure pulsation increases obviously in low frequency region, and the whole amplitude of vibration signal increases obviously with the increase of gas content. Especially in the low frequency region, with the increase of gas content, the vibration decreases first, then increases, and then decreases. When the inlet gas content is 5, the vibration is maximum, and the inlet gas content is more than 5%. Low frequency vibration energy will also become an important component of pump system vibration energy. Based on the Eulerian heterogeneous flow model, the steady and unsteady numerical calculation of the model pump is carried out under different flow rate and different inlet gas content. The conclusion is as follows: when the inlet gas content exceeds 3%, The initial bubble diameter is an important factor to be considered in the calculation. With the increase of the gas content, the gas tends to move along the suction side towards the outlet, and the gas can improve the inlet reflux phenomenon of the impeller to a certain extent. The accumulation of gas in the impeller is related to the formation of swirl. When the inlet gas content reaches 3, the amplitude of the low frequency region will increase slightly, resulting in a wide band pulsation, and the range of the wide frequency fluctuation in the low frequency region will become wider with the increase of the gas content. The higher the gas content is, the more obvious is the influence on the low frequency broadband pulsation.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TH311

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本文編號(hào)：2144597