本文選題：外混式自吸離心泵 + 實(shí)驗(yàn)測(cè)試��； 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：由于普通離心泵吸入液面如果在葉輪以下,啟動(dòng)時(shí)必須預(yù)先灌水,為了在泵體內(nèi)部及吸入管路能夠存住水,入口需安裝閥門,泵工作時(shí)閥門造成的水力損失較大,且閥口容易夾雜石塊、樹(shù)枝等雜物,導(dǎo)致封水不嚴(yán)而無(wú)法灌滿水,這樣自吸泵隨之出現(xiàn)并得到廣泛的應(yīng)用,自吸泵具有體積小、工作可靠、便于遠(yuǎn)程集中控制等特點(diǎn),近年來(lái)人們對(duì)于自吸泵性能做了大量的理論研究工作,其一:水力性能設(shè)計(jì)是否優(yōu)秀是影響自吸性能的關(guān)鍵因素。其二:自吸泵的啟動(dòng)階段是非常紊亂的瞬態(tài)氣液兩相流動(dòng)過(guò)程,同時(shí)在啟動(dòng)階段氣液混合和分離的效果與否對(duì)于自吸性能有著顯著影響。本文主要的研究?jī)?nèi)容及結(jié)果如下:(1)較為全面的概述和總結(jié)了自吸泵的研究近況及發(fā)展方向。(2)主要從自吸泵現(xiàn)有設(shè)計(jì)理論研究成果總結(jié)的基礎(chǔ)上,根據(jù)電站的實(shí)際需要采用速度系數(shù)法對(duì)ZX80-65-178自吸式離心泵進(jìn)行設(shè)計(jì),滿足規(guī)定的設(shè)計(jì)目標(biāo)和自吸性能要求。(3)應(yīng)用計(jì)算流體力學(xué)CFD對(duì)自吸泵的內(nèi)部流場(chǎng)進(jìn)行定常模擬計(jì)算,分析和研究該泵在各工況下的能量性能、內(nèi)部流動(dòng)機(jī)理、速度特征,并進(jìn)行相關(guān)的外特性試驗(yàn)驗(yàn)證,檢驗(yàn)自吸泵水力設(shè)計(jì)是否達(dá)到設(shè)計(jì)目標(biāo)。(4)回流孔設(shè)計(jì)是在經(jīng)驗(yàn)公式設(shè)計(jì)的基礎(chǔ)上進(jìn)行估算得到,一般很難達(dá)到最優(yōu)設(shè)計(jì)值,對(duì)于特定的自吸泵,存在一個(gè)最佳回流孔的面積及其安放位置,在初次設(shè)計(jì)的基礎(chǔ)上根據(jù)數(shù)值模擬結(jié)果研究和分析回流孔的內(nèi)部流動(dòng)特性,對(duì)回流孔大小重新定義,分析得到隨著回流孔大小的變化,導(dǎo)致回流孔兩側(cè)壓力差及其回流量的變化,最終反映到自吸泵外特性的變化,從而確定該自吸泵回流孔的最佳面積。(5)自吸泵的啟動(dòng)過(guò)程是三維非穩(wěn)態(tài)的湍流運(yùn)動(dòng),實(shí)驗(yàn)發(fā)現(xiàn)自吸泵的自吸初期含氣率有一個(gè)激增的過(guò)程,最大能達(dá)到一半。所以本文通過(guò)氣液兩相流數(shù)值模擬理論研究葉輪入口在不同含氣率情形下泵體內(nèi)部的氣液兩相流動(dòng)特點(diǎn),為探究啟動(dòng)階段的流動(dòng)機(jī)理具有一定的參考價(jià)值。(6)本章主要是非穩(wěn)態(tài)數(shù)值模擬,主要研究自吸泵在水力設(shè)計(jì)基礎(chǔ)上的壓力脈動(dòng)變化情況,運(yùn)用基于結(jié)構(gòu)化網(wǎng)格大渦數(shù)值模擬理論的研究方法,通過(guò)設(shè)置泵內(nèi)重要部位監(jiān)測(cè)點(diǎn)監(jiān)測(cè)其壓力變化,從而得到監(jiān)測(cè)點(diǎn)的壓力脈動(dòng)時(shí)域圖和通過(guò)快速傅里葉的變化獲得頻域圖,同時(shí)通過(guò)速度和壓力云圖進(jìn)行分析說(shuō)明。
[Abstract]:If the suction level of ordinary centrifugal pump is below the impeller, it must be filled in advance when starting. In order to store water inside the pump body and in the suction pipeline, the valve must be installed at the entrance of the pump, and the hydraulic loss caused by the valve when the pump is working is large. And the valve opening is easily mixed with stones, branches and other sundries, resulting in the sealing of water is not strict enough to fill the water, so the self-priming pump appears and is widely used. The self-priming pump has the characteristics of small volume, reliable work, convenient remote centralized control, etc. In recent years, people have done a lot of theoretical research on the performance of self-priming pump. Firstly, whether the design of hydraulic performance is good or not is the key factor to affect the self-priming performance. Second, the starting stage of the self-priming pump is a very disordered transient gas-liquid two-phase flow process. At the same time, the effect of gas-liquid mixing and separation has a significant effect on the self-priming performance. The main research contents and results of this paper are as follows: (1) A more comprehensive overview and summary of the research status and development direction of the self-priming pump. (2) based on the summary of the research results of the existing design theory of the self-priming pump, The ZX80-65-178 self-priming centrifugal pump is designed according to the actual needs of the power station. The design objective and the self-priming performance requirement are met. The CFD of computational fluid dynamics is applied to the steady simulation of the internal flow field of the self-priming pump. The energy performance, internal flow mechanism, velocity characteristics of the pump under various operating conditions are analyzed and studied. Check whether the hydraulic design of the self-priming pump has reached the design target.) the design of the backflow hole is estimated on the basis of the empirical formula design. It is generally difficult to reach the optimal design value. For a specific self-priming pump, There exists an optimum reflow hole area and its location. Based on the numerical simulation results, the internal flow characteristics of the reflow hole are studied and analyzed, and the size of the reflow hole is redefined. The results show that with the change of the size of the reflux hole, the pressure difference on both sides of the reflux hole and its reflux volume change, which is reflected in the change of the external characteristics of the self-priming pump. Thus, it is determined that the starting process of the self-priming pump is a three-dimensional unsteady turbulent motion. It is found that the initial gas content of the self-priming pump has a surge process, the maximum of which can reach half. In this paper, the characteristics of gas-liquid two-phase flow in the impeller inlet under different gas content are studied by numerical simulation of gas-liquid two-phase flow. In order to explore the flow mechanism of start-up stage, this chapter is mainly about unsteady numerical simulation, which mainly studies the variation of pressure fluctuation on the basis of hydraulic design of self-priming pump. Based on the theory of structured grid large eddy numerical simulation, the pressure variation is monitored by setting the monitoring points in important parts of the pump, and the time-domain map of pressure pulsation and the frequency domain diagram are obtained by the change of fast Fourier transform. At the same time, the velocity and pressure clouds are analyzed and explained.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TV136.2;TV734

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