發(fā)布時間：2018-02-02 02:37

  本文關(guān)鍵詞： LNG潛液泵 誘導輪 導葉 CFD 低溫液體空化　出處：《上海大學》2015年碩士論文　論文類型：學位論文

【摘要】：近年來,清潔能源液化天然氣(LNG)在世界能源供應(yīng)中的比例迅速增加,成為全球增長最迅猛的石油化工產(chǎn)品之一。LNG在整個產(chǎn)業(yè)鏈中的轉(zhuǎn)移需要借助液化天然氣(LNG)潛液泵來實現(xiàn)。目前,國外幾家公司基本壟斷著LNG潛液泵的供應(yīng),若自主研制LNG潛液泵,則必須先對LNG潛液泵的設(shè)計進行研究。本文以LNG加注站裝置中的LNG潛液泵為具體研究對象,在把握其結(jié)構(gòu)特點的基礎(chǔ)上,分析、研究并總結(jié)設(shè)計方法,研制LNG潛液泵樣機,旨在為今后LNG潛液泵的設(shè)計制造提供理論基礎(chǔ)和技術(shù)支撐。全文的主要工作如下:一、LNG潛液泵主要過流部件的水力設(shè)計研究這部分重點分析和研究葉輪、誘導輪和導葉等主要過流部件的水力設(shè)計方法,兼顧泵的性能及結(jié)構(gòu)合理性,對葉輪、誘導輪、導葉進行水力設(shè)計。葉輪設(shè)計采用基于一元設(shè)計理論的傳統(tǒng)設(shè)計方法,針對LNG潛液泵的特點,考慮液體流經(jīng)出液管段的水力損失來計算理論揚程,以保證泵整機的揚程。誘導輪的設(shè)計揚程需根據(jù)葉輪的必需汽蝕余量來確定�？紤]到計算流體動力學(CFD)方法可以仿真泵內(nèi)的空化流動,本文通過數(shù)值實驗方法來確定葉輪的必需汽蝕余量,并綜合考慮性能的要求和結(jié)構(gòu)的合理性,確定誘導輪的幾何參數(shù)。導葉采用了一種特殊的結(jié)構(gòu),其優(yōu)點是可有效減小泵的徑向尺寸。由于這種導葉尚無確定的設(shè)計方法,本文借鑒徑向?qū)~的設(shè)計方法,確定LNG潛液泵導葉的幾何參數(shù),并通過數(shù)值方法研究導葉進口喉部寬度和折轉(zhuǎn)角對泵水力性能的影響,發(fā)現(xiàn)進口喉部寬度對泵揚程和效率影響較大,且存在最優(yōu)值,而進口折轉(zhuǎn)角對泵揚程和效率則影響較小。二、LNG潛液泵水力性能和空化性能預(yù)測本文在水力設(shè)計完成后,通過數(shù)值模擬的方法預(yù)測泵的水力和空化性能,并對泵內(nèi)的流動和空化特征進行分析。水力性能預(yù)測時,將LNG潛液泵的所有過流區(qū)域作為計算域,在不同流量下計算LNG潛液泵的性能參數(shù);空化性能預(yù)測時,計算域則主要包括誘導輪和一級葉輪的過流部分,分別在等溫和考慮熱力學效應(yīng)情況下進行空化數(shù)值模擬,分析熱力學效應(yīng)對低溫空化的影響。結(jié)果表明:預(yù)測的潛液泵水力性能可以達到設(shè)計要求,流量-揚程曲線在小流量工況較為平坦,大流量工況下降較快,且泵的高效率區(qū)較寬。低溫液體熱力學效應(yīng)對泵的空化性能影響顯著,考慮熱力學效應(yīng)計算的泵必需汽蝕余量比等溫情況下計算的值要小。三、LNG潛液泵樣機研制及試驗在LNG潛液泵樣機設(shè)計的基礎(chǔ)上,研制LNG潛液泵樣機,以液氮為介質(zhì),分別針對現(xiàn)有相同設(shè)計參數(shù)的進口LNG潛液泵和新研制的LNG潛液泵進行性能試驗。試驗結(jié)果表明新研制的LNG潛液泵運行正常,其效率在小流量工況時低于進口泵,大流量時高于進口泵,且高效率區(qū)更寬,這將有利于該泵的實際應(yīng)用。
[Abstract]:In recent years, the proportion of clean energy, liquefied natural gas (LNG) in the world energy supply has increased rapidly. To become one of the fastest growing petrochemical products in the world. The transfer of LNG in the whole industry chain needs to be realized by means of liquefied natural gas (LNG) submersible pump. Several foreign companies basically monopolize the supply of LNG submersible pumps, if we develop LNG submersible pumps independently. The design of the LNG submersible pump must be studied first. This paper takes the LNG submersible pump in the LNG filling station as the specific research object, and analyzes it on the basis of grasping its structural characteristics. This paper studies and summarizes the design method and develops the prototype of LNG submersible pump in order to provide the theoretical foundation and technical support for the design and manufacture of LNG submersible pump in the future. The main work of this paper is as follows: 1. Study on hydraulic Design of main Over-flow parts of LNG submersible pump; this part focuses on the hydraulic design methods of impeller, induction wheel and guide vane, taking into account the performance and structural rationality of the pump, and the impeller. The impeller design adopts the traditional design method based on the univariate design theory, according to the characteristics of LNG submersible pump, considering the hydraulic loss of liquid flowing through the outlet pipe to calculate the theoretical head. In order to ensure the head of the whole pump, the design head of the induction wheel should be determined according to the necessary cavitation allowance of the impeller. Considering the computational fluid dynamics (CFD) method, the cavitation flow in the pump can be simulated. In this paper, the necessary cavitation allowance of impeller is determined by numerical experiment method, and the geometric parameters of induction wheel are determined by considering the requirements of performance and the rationality of structure. The guide vane adopts a special structure. The advantages are that the radial dimension of the pump can be reduced effectively. As there is no definite design method for the guide vane, the geometric parameters of the guide vane of the LNG submersible pump are determined by using the design method of the diameter-guide vane. The influence of inlet throat width and angle of guide vane on the hydraulic performance of the pump is studied by numerical method. It is found that the inlet throat width has great influence on the head and efficiency of the pump, and there is an optimum value. The hydraulic performance and cavitation performance of LNG submersible pump are predicted by numerical simulation after the completion of hydraulic design. The flow and cavitation characteristics in the pump are analyzed. When the hydraulic performance is predicted, the performance parameters of the LNG submersible pump are calculated under different flow rates by taking all the flow areas of the submersible pump as the computational domain. In the prediction of cavitation performance, the numerical simulation of cavitation is carried out in the case of isothermal consideration of thermodynamic effect, which mainly includes the overflowing part of the induction wheel and the first stage impeller. The effect of thermodynamic effect on cavitation at low temperature is analyzed. The results show that the hydraulic performance of the submersible pump can meet the design requirements, the flow-head curve is flat in the small flow condition, and the large flow condition decreases rapidly. The thermodynamic effect of low temperature liquid has a significant effect on the cavitation performance of the pump, and the necessary cavitation allowance calculated by considering the thermodynamic effect is smaller than that calculated under isothermal condition. Development and test of LNG submersible pump prototype on the basis of LNG submersible pump prototype, the prototype of LNG submersible pump is developed, in which liquid nitrogen is used as the medium. The performance tests of the imported LNG submersible pump and the newly developed LNG submersible pump with the same design parameters have been carried out respectively. The test results show that the newly developed LNG submersible pump is running normally. The efficiency of the pump is lower than that of the imported pump in the small flow condition, and higher than that of the inlet pump in the large flow rate, and the high efficiency zone is wider, which will be beneficial to the practical application of the pump.
【學位授予單位】：上海大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE974.1

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