本文選題：離心泵　切入點：旋轉(zhuǎn)失速　出處：《中國農(nóng)業(yè)大學》2015年博士論文

【摘要】：水泵在小流量工況下運行時,因偏離設計點,葉輪中容易出現(xiàn)失速現(xiàn)象。失速團不斷地產(chǎn)生和脫落會誘發(fā)壓力脈動,使得水泵噪音增強,振動加劇,影響機組安全運行。本文采用大渦模擬方法對離心泵內(nèi)的失速現(xiàn)象進行了較系統(tǒng)的研究。 首先,建立了離心泵失速計算模型。針對離心泵失速流動特征,采用典型SGS模型對離心泵內(nèi)部流動進行了計算,提出了適合離心泵失速的計算模型,構建了采用動態(tài)混合非線性模型(DMNM)求解失速流場的計算策略,為準確分析失速過程奠定了基礎。 其次,提出了離心泵中失速的表征參數(shù)及兩種類型失速發(fā)生的條件。當葉片數(shù)為偶數(shù)時,會發(fā)生“交替失速”流動現(xiàn)象；當葉片數(shù)為奇數(shù)時,會發(fā)生“旋轉(zhuǎn)失速”流動現(xiàn)象。在出現(xiàn)“交替失速”的前提下,隨著葉片數(shù)增多,失速團的數(shù)量也隨之增多,失速渦頻率也隨之變化；在出現(xiàn)“旋轉(zhuǎn)失速”的前提下,隨著葉片數(shù)增多,失速團的數(shù)量也隨之增多,轉(zhuǎn)速變大,失速渦頻率也隨之增大。 第三,利用所建立的離心泵失速計算模型,分析了失速條件下葉輪流動結構及壓力脈動特性,給出了兩類失速狀態(tài)下失速團的演變過程及其誘導的壓力脈動變化規(guī)律。對于“交替失速”,失速團相對葉輪周向未發(fā)生旋轉(zhuǎn),但是失速流道主渦不斷擺動,在下游分裂出出口渦。出口渦周期性地增長和脫落,在葉片上所產(chǎn)生的壓力脈動表現(xiàn)為中心頻率幅值較高的“寬帶頻率”；隨著主渦的衰減,在主渦的上游還會分離成為一個面積較小的渦,并與主渦相互融合,主渦經(jīng)歷“衰減-分裂-融合-壯大”的周而復始過程,在葉片上產(chǎn)生的壓力脈動表現(xiàn)出幅值較高的低頻。對于“旋轉(zhuǎn)失速”,失速團產(chǎn)生于葉片吸力面頭部附近,沿圓周方向向葉片壓力面運動,并逐漸衰減；當旋轉(zhuǎn)失速發(fā)生以后,葉片上的壓力脈動幅值遠大于非失速工況,葉片上的壓力脈動頻率以失速渦頻率為主。 第四,研究了隔舌區(qū)域動靜干涉和失速的相互作用,揭示了失速條件下隔舌區(qū)壓力脈動傳播機理。在小流量工況下,當葉輪中發(fā)生“交替失速”現(xiàn)象以后,葉輪流道通過隔舌處時會有“固定失速”的流動現(xiàn)象。在“交替失速”初始階段,隔舌區(qū)“固定失速”對壓力脈動的影響較弱,“交替失速”的影響占主導；而當流量進一步減小以后,隔舌區(qū)“固定失速”對壓力脈動的影響占主導,削弱了“交替失速”的作用。而在葉片區(qū)壓力脈動中,“固定失速”始終占主導,隔舌處強烈的動靜干涉作用削弱了旋渦脫落所造成的低頻,主要頻率為轉(zhuǎn)頻及其諧頻。 本文取得的研究成果,為改善離心泵葉輪設計、提高離心泵在非設計工況下的運行穩(wěn)定性具有指導意義。
[Abstract]:The impeller is prone to stall because of deviation from the design point when the pump is running under small flow conditions.The constant occurrence and shedding of stall mass will induce pressure pulsation, which will increase the noise and vibration of the pump and affect the safe operation of the unit.In this paper, the stall phenomenon in centrifugal pump is studied systematically by means of large eddy simulation.Firstly, the stall calculation model of centrifugal pump is established.According to the characteristics of stall flow of centrifugal pump, the typical SGS model is used to calculate the flow inside the centrifugal pump, and a calculation model suitable for stall of centrifugal pump is put forward. The calculation strategy of solving stall flow field using dynamic mixed nonlinear model (DMNM) is constructed.It lays a foundation for accurate analysis of stall process.Secondly, the parameters of stall in centrifugal pump and the conditions of two types of stall are proposed.When the number of blades is even, the phenomenon of "alternate stall" flow will occur, and when the number of blades is odd, the phenomenon of "rotational stall" will occur.On the premise of "alternate stall", the number of stall clusters increases with the increase of blade number, and the frequency of stall vortex also changes.The number of stall clusters increases, the rotational speed increases and the stall vortex frequency increases.Thirdly, the flow structure and pressure pulsation characteristics of impeller under stall condition are analyzed by using the established stall calculation model of centrifugal pump. The evolution process of stall mass and its induced pressure fluctuation under two kinds of stall conditions are given.For "alternate stall", the stall group does not rotate relative to the circumference of the impeller, but the main vortex of the stall channel wobbles continuously and splits out the exit vortex downstream.The pressure pulsation of the exit vortex increases and shedding periodically, and the pressure pulsation on the blade is characterized by a "wide band frequency" with higher central frequency amplitude. With the attenuation of the main vortex, it will be separated into a smaller vortex in the upper reaches of the main vortex.The main vortex goes through the process of "attenuation-splitting-fusing-growing", and the pressure pulsation on the blade shows a high amplitude of low frequency.For "rotating stall", the stall mass occurs near the head of the suction surface of the blade and moves toward the blade pressure surface in the circumferential direction, and gradually attenuates. When the rotating stall occurs, the amplitude of the pressure pulsation on the blade is much larger than that on the non-stall condition.The pressure pulsation frequency on the blade is mainly stall vortex frequency.Fourthly, the interaction between static and static interference and stall in tongue septum is studied, and the propagation mechanism of pressure pulsation in tongue septum is revealed.Under the condition of small flow rate, when the phenomenon of "alternate stall" occurs in the impeller, there will be a "fixed stall" when the impeller passage passes through the tongue.In the initial stage of "alternate stall", the effect of "fixed stall" on pressure pulsation in the tongue septum is weak, and the effect of "alternate stall" is dominant, but when the flow rate decreases further,The influence of fixed stall on pressure pulsation is dominant, which weakens the effect of alternate stall.In the pressure pulsation of the blade region, "fixed stall" always dominates. The strong static and static interference at the tongue impairs the low frequency caused by vortex shedding, and the main frequency is rotation frequency and harmonic frequency.The research results obtained in this paper are of guiding significance for improving the design of centrifugal pump impeller and improving the operation stability of centrifugal pump under off-design conditions.
【學位授予單位】：中國農(nóng)業(yè)大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TH311

【參考文獻】

相關期刊論文 前10條

1 于波,文吉運;大渦模擬在水力機械內(nèi)流數(shù)值模擬中的應用[J];大電機技術;2005年01期

2 吳喜東;游超;王煥茂;;牛欄江-滇池補水工程水泵水力優(yōu)化設計[J];大電機技術;2010年06期

3 薛敦松，，李振林，孫自祥;非設計工況下低比速泵葉輪內(nèi)不穩(wěn)定流動和湍流度試驗[J];工程熱物理學報;1994年02期

4 王春瑞;岳林;;軸流壓氣機失速特征識別[J];航空動力學報;2011年08期

5 姜偉;曹海紅;仇寶云;問澤杭;裴蓓;申劍;;大型水泵機組故障特點與原因分析[J];流體機械;2009年06期

6 梁開洪;曹樹良;陳炎;祝寶山;;軸流泵葉輪內(nèi)部流場大渦模擬及分析[J];流體機械;2009年11期

7 祝磊;袁壽其;袁建平;周建佳;金榮;王慧;;不同型式隔舌離心泵動靜干涉作用的數(shù)值模擬[J];農(nóng)業(yè)工程學報;2011年10期

8 牟介剛;張生昌;鄭水華;鄧鴻英;;離心泵性能曲線產(chǎn)生駝峰的機理及消除措施[J];農(nóng)業(yè)機械學報;2006年04期

9 瞿麗霞;王福軍;叢國輝;姚志峰;;雙吸離心泵葉片區(qū)壓力脈動特性分析[J];農(nóng)業(yè)機械學報;2011年09期

10 潘中永;李俊杰;李曉俊;袁壽其;;斜流泵不穩(wěn)定特性及旋轉(zhuǎn)失速研究[J];農(nóng)業(yè)機械學報;2012年05期

相關博士學位論文 前2條

1 張偉;葉片泵非設計工況葉輪內(nèi)部流動分析和預測[D];上海大學;2011年

2 彭玉成;三峽電站左岸6號機組小開度工況異常振動研究[D];華中科技大學;2007年

本文編號：1730677