本文選題：離心泵 + 固液兩相��；參考：《浙江大學(xué)》2013年博士論文

【摘要】：離心泵通常主要在穩(wěn)定工況下運(yùn)行,其工作轉(zhuǎn)速、工況等基本不變或者變化非常緩慢,因此對(duì)離心泵的研究主要集中在穩(wěn)定工況下進(jìn)行。隨著離心泵應(yīng)用領(lǐng)域的拓展以及系統(tǒng)復(fù)雜程度的提高,離心泵也會(huì)在非穩(wěn)定工況下運(yùn)行,如啟動(dòng)、停機(jī)和轉(zhuǎn)速變化等瞬態(tài)工況,離心泵在非穩(wěn)定工況運(yùn)行的水力性能日益受到重視,因此非常有必要開(kāi)展離心泵在瞬態(tài)工況下的性能研究。 本論文以在瞬態(tài)工況下運(yùn)行的離心泵為研究對(duì)象,重點(diǎn)對(duì)啟動(dòng)過(guò)程中的水力性能進(jìn)行了較為詳細(xì)和深入的系統(tǒng)研究,獲得了當(dāng)輸送介質(zhì)中含有固體顆粒時(shí)的離心泵瞬態(tài)啟動(dòng)特性。論文首先根據(jù)動(dòng)量矩定理提出了一種描述不可壓縮流體機(jī)械瞬態(tài)操作條件下性能的廣義歐拉方程式,借助于該方程式開(kāi)展離心泵在各類(lèi)瞬態(tài)操作條件下附加理論揚(yáng)程的定量計(jì)算；其次,運(yùn)用動(dòng)網(wǎng)格方法進(jìn)行了離心泵啟動(dòng)過(guò)程的數(shù)值仿真計(jì)算研究,建立了基于數(shù)值模擬的離心泵瞬態(tài)性能研究方法；再次,開(kāi)展了離心泵啟動(dòng)過(guò)程的外特性實(shí)驗(yàn)測(cè)試研究,借助于無(wú)量綱分析方法揭示了離心泵啟動(dòng)過(guò)程的瞬態(tài)特性；最后,采用數(shù)值模擬方法開(kāi)展了離心泵輸送介質(zhì)中含固體顆粒時(shí)的啟動(dòng)過(guò)程流動(dòng)計(jì)算,獲得了其瞬態(tài)特性。 論文的主要研究工作如下： 1.從動(dòng)量矩定理和水力機(jī)械內(nèi)部流動(dòng)理論出發(fā),推導(dǎo)了一種描述不可壓縮流體機(jī)械瞬態(tài)操作過(guò)程性能的廣義歐拉方程式。該方程式可較全面地反映了整個(gè)葉片厚度變化和葉片型線變化對(duì)附加理論揚(yáng)程的影響,并可被用于泵、風(fēng)機(jī)、透平等不可壓縮流體機(jī)械在各類(lèi)瞬態(tài)操作過(guò)程中的附加理論揚(yáng)程(或壓頭、壓升)的定量預(yù)測(cè)。 2.運(yùn)用動(dòng)網(wǎng)格方法開(kāi)展了離心泵輸送清水介質(zhì)時(shí)的快速啟動(dòng)過(guò)程的數(shù)值模擬研究,建立了基于數(shù)值模擬的離心泵瞬態(tài)操作過(guò)程的研究方法。論文研究工作中,建立了一個(gè)包含離心泵模型在內(nèi)的循環(huán)管路系統(tǒng),并在系統(tǒng)中設(shè)置了定壓點(diǎn),數(shù)值模擬中對(duì)整個(gè)系統(tǒng)進(jìn)行計(jì)算。通過(guò)數(shù)值計(jì)算獲得了啟動(dòng)過(guò)程中的許多特性,包括外特性的變化和內(nèi)部流場(chǎng)的演化特性。進(jìn)口壓力呈現(xiàn)先降后升特性,流量在啟動(dòng)初期上升較為緩慢。無(wú)量綱流量在初始階段快速上升至穩(wěn)定值；無(wú)量綱揚(yáng)程在啟動(dòng)初始階段存在極大值,隨后迅速下降低于準(zhǔn)穩(wěn)態(tài)值,而后又不斷上升接近于準(zhǔn)穩(wěn)態(tài)值。 3.在所搭建的離心泵瞬態(tài)性能測(cè)試實(shí)驗(yàn)臺(tái)上,對(duì)三種典型葉輪結(jié)構(gòu)(普通閉式葉輪、復(fù)合葉輪和開(kāi)式葉輪)的離心泵進(jìn)行了清水介質(zhì)的啟動(dòng)過(guò)程實(shí)驗(yàn)測(cè)試研究。通過(guò)實(shí)驗(yàn)獲得了啟動(dòng)過(guò)程中轉(zhuǎn)速、流量、揚(yáng)程和軸功率隨時(shí)間的變化結(jié)果,分析了各個(gè)物理量的變化特性。啟動(dòng)過(guò)程中轉(zhuǎn)速上升規(guī)律基本穩(wěn)定,不依賴于啟動(dòng)后穩(wěn)定工況點(diǎn)的變化而變化；流量在啟動(dòng)初期上升較為緩慢,延遲于轉(zhuǎn)速而上升到穩(wěn)定值,并且隨閥門(mén)開(kāi)度的增加延遲變得更為嚴(yán)重；在啟動(dòng)過(guò)程中普遍存在壓力沖擊和軸功率沖擊現(xiàn)象。 4.首先采用基于歐拉-歐拉方法的多相流模型,對(duì)固液兩相流中固相屬性對(duì)水力輸送性能的影響以及泵流道內(nèi)固體顆粒的分布進(jìn)行了數(shù)值計(jì)算研究,分析了內(nèi)部流場(chǎng)的變化特性。在離心泵啟動(dòng)實(shí)驗(yàn)中獲得的轉(zhuǎn)速與流量測(cè)試結(jié)果基礎(chǔ)上,編寫(xiě)用戶自定義函數(shù)施加到泵葉輪上和進(jìn)口處充當(dāng)計(jì)算邊界條件,采用動(dòng)網(wǎng)格方法開(kāi)展了離心泵輸送介質(zhì)中含固體顆粒時(shí)的啟動(dòng)計(jì)算。研究發(fā)現(xiàn)當(dāng)輸送介質(zhì)發(fā)生變化時(shí),啟動(dòng)過(guò)程所表現(xiàn)出的性能差別是非常大的。啟動(dòng)前期瞬態(tài)性能基本相同,差別主要集中在啟動(dòng)后期；輸送固液兩相流時(shí)的揚(yáng)程呈現(xiàn)先升后降的變化特性,明顯區(qū)別于介質(zhì)為清水時(shí)的持續(xù)上升趨勢(shì)；當(dāng)輸送介質(zhì)含固體顆粒時(shí),揚(yáng)程滯后于清水介質(zhì)時(shí)的情形而達(dá)到穩(wěn)定狀態(tài)。
[Abstract]:Centrifugal pumps usually run in stable condition, the working speed, working basic constant or change very slowly, so the research of centrifugal pump is mainly concentrated in the stable condition. With the application development of the centrifugal pump and the increase of system complexity, centrifugal pump will run in unsteady conditions such as start, stop and speed change of transient conditions, the centrifugal pump becomes more and more important in the hydraulic performance of non steady operation, so it is very necessary to carry out research on the performance of centrifugal pump under transient conditions.
In this paper, a centrifugal pump running in transient conditions as the research object, focusing on the hydraulic performance in the process of starting a more detailed and in-depth study of the system, the centrifugal pump transient when the transport medium containing solid particles when the starting characteristics. Firstly, according to the momentum moment theorem is proposed to describe not the generalized Euler equation of compressible fluid mechanical properties of transient operating conditions, with the help of this equation to carry out quantitative pump additional theoretical head in all kinds of transient operating condition are calculated; secondly, using the dynamic mesh method obtained from numerical simulation of heart pump start calculation in the course of study, a numerical simulation method based on the study on the transient performance of centrifugal pump again, the external characteristics; experimental study of centrifugal pump during starting period, with the help of dimensionless analysis method to reveal the transient of the centrifugal pump during starting period In the end, the numerical simulation method is used to carry out the calculation of the starting process flow of the solid particles in the conveying medium of the centrifugal pump, and the transient characteristics are obtained.
The main research work of this paper is as follows:
Starting from the 1. theorem of moment of momentum and hydraulic mechanical flow theory, generalized Euler equation is derived to describe an incompressible fluid mechanical transient operation process performance. This equation can reflect the influence of the blade thickness and the blade profile changes on the theory of additional lift, and can be used to pump air. Additional theoretical lift machine, such as turbine incompressible fluid in various types of machinery during transient operation (or pressure, pressure rise) quantitative prediction.
2. simulation study using dynamic mesh method to carry out a centrifugal pump water medium fast startup process is developed based on the numerical method of centrifugal pump transient process based on numerical simulation. The research work, establish a complete model of centrifugal pump, circulation system, and set up a constant pressure point in the system in the calculation of the whole system. The numerical simulation obtained by numerical calculation. Many characteristics in the starting process, including the evolution characteristics of external characteristics and internal flow field changes. The inlet pressure is decreased and then the flow characteristics in the early start to rise more slowly. The dimensionless flow in the initial stage of rapid rise to a stable value; the dimensionless head in the initial stage of starting up the maximum value, then decreased rapidly than the quasi steady value, and then rising close to the quasi steady state value.
3. in the transient performance of centrifugal pump test bench is built on three kinds of typical structure of impeller (ordinary closed impeller, complex impeller and open impeller centrifugal pump) were studied experimental start-up process of water. Through the experiment speed, start the process of the flow, the changes of head and shaft power over time, to investigate the characteristics of various physical quantities. During the startup speed rise of basic stability, does not depend on changes in the starting point and the stable condition after change; flow increases slowly in the early start, delay in speed and rise to a stable value, and with the increase of valve opening delay becomes more serious there; pressure shock and shaft power shock phenomenon during startup.
The first 4. phase flow model based on Euler Euler method, the effect of solid phase properties of solid-liquid two-phase flow on the transmission performance of hydraulic pump flow and distribution of solid particles was studied numerically, analyzed the change characteristics of the internal flow field of centrifugal pump. In the experiment the speed and flow on the basis of the test results and write user defined functions applied to the pump impeller and inlet as boundary condition, the dynamic mesh method containing solid particles in the conveying medium when starting the calculation of centrifugal pump was carried out. The study found that when the transmission medium is changed, the performance difference is shown in the starting process is very large. Before the start of transient performance the same, the difference is mainly concentrated in the late start; transportation of solid-liquid two-phase flow when the head changes characteristics at first and then decreased, significantly different from the medium water holding time The rising trend is continued. When the medium contains solid particles, the lift falls behind the water medium and reaches a stable state.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類(lèi)號(hào)】：TH311

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本文編號(hào)：1730924