本文選題：離心泵 + 葉片前緣空化��； 參考：《江蘇大學(xué)》2013年博士論文

【摘要】：本文的研究工作在國(guó)家自然科學(xué)基金重點(diǎn)項(xiàng)目“水力機(jī)械的空化特性及對(duì)策”(51239005)、國(guó)家科技支撐計(jì)劃項(xiàng)目“百萬(wàn)千瓦級(jí)核電離心泵關(guān)鍵技術(shù)研究”(2011BAF14B04)和江蘇省研究生創(chuàng)新基金“離心泵空化不穩(wěn)定流動(dòng)機(jī)理及動(dòng)力特性研究”(CXZZ11_0564)的資助下展開(kāi)。 對(duì)于目前常用的低比速離心泵來(lái)說(shuō),效率低是造成該類(lèi)泵運(yùn)行成本過(guò)高的一個(gè)重要原因,因此對(duì)低比速離心泵進(jìn)行技術(shù)改進(jìn)具有顯著的經(jīng)濟(jì)效益和社會(huì)效益。提高泵效率一個(gè)非常有效的方法就是通過(guò)增加泵的轉(zhuǎn)速以提高泵的比轉(zhuǎn)速,而高速化對(duì)離心泵的運(yùn)行穩(wěn)定性和空化性能均提出更高的要求。本文以離心泵葉片前緣空化的非定常流動(dòng)特性為研究對(duì)象,采用理論分析、試驗(yàn)研究和數(shù)值模擬相結(jié)合的方法,對(duì)離心泵的空化狀態(tài)監(jiān)測(cè)、空化流數(shù)值模擬、空化導(dǎo)致?lián)P程下降現(xiàn)象以及泵下游幾何參數(shù)對(duì)空化不穩(wěn)定性的影響等內(nèi)容進(jìn)行了系統(tǒng)的研究,并初步分析了離心泵非設(shè)計(jì)工況下的空化和駝峰特性。本文的主要工作和創(chuàng)新成果如下： (1)定量研究了網(wǎng)格質(zhì)量對(duì)離心泵數(shù)值模擬計(jì)算精度的影響,系統(tǒng)探討了邊界層網(wǎng)格密度和湍流模型之間的關(guān)系,并初步建立了邊界層網(wǎng)格和湍流模型之間的評(píng)價(jià)方式。從流體流動(dòng)角度分析了全流道模型在離心泵數(shù)值求解中的優(yōu)勢(shì)并研究了區(qū)域交界面對(duì)非設(shè)計(jì)工況模擬結(jié)果的影響,針對(duì)計(jì)算區(qū)域的拓?fù)鋲K生成和結(jié)構(gòu)化網(wǎng)格劃分方法中存在的問(wèn)題,建立并優(yōu)化了基于泵腔一體化的離心泵全流道結(jié)構(gòu)化網(wǎng)格。 (2)搭建了可用于離心泵空化不穩(wěn)定性測(cè)試的閉式試驗(yàn)系統(tǒng),實(shí)現(xiàn)了泵性能參數(shù)和離心泵內(nèi)部水力噪聲、進(jìn)出口壓力波動(dòng)、振動(dòng)以及電機(jī)的定子電流等動(dòng)態(tài)信號(hào)的同步采集。采用4種數(shù)理統(tǒng)計(jì)方法,包括概率密度分布(PDF)、方差、均方差和均方根等,分析了葉輪外徑D2=174mm離心泵進(jìn)口壓力波動(dòng)的時(shí)域信息,研究結(jié)果表明4種數(shù)理統(tǒng)計(jì)方法都可以預(yù)測(cè)泵的揚(yáng)程斷裂工況。同時(shí)引入電機(jī)的定子電流分析法,通過(guò)對(duì)比分析時(shí)域和頻域條件下定子電流的結(jié)果,發(fā)現(xiàn)定子電流對(duì)電機(jī)的運(yùn)行狀態(tài)非常敏感,能有效地監(jiān)測(cè)泵內(nèi)的空化狀態(tài)。定子電流的時(shí)域結(jié)果能夠表征離心泵的空化不穩(wěn)定工況和揚(yáng)程斷裂工況,定子電流的頻域結(jié)果能夠捕捉泵的空化初生工況。 (3)揭示了離心泵揚(yáng)程下降的原因,并初步掌握了空化誘導(dǎo)揚(yáng)程下降的機(jī)理,即空化的出現(xiàn)導(dǎo)致泵產(chǎn)生附加水力損失。將空化引起的水力損失分為兩類(lèi)并對(duì)它們進(jìn)行詳細(xì)的闡述：第一類(lèi)是空化引起流動(dòng)流態(tài)的變化,即空化對(duì)泵性能的直接作用,這種直接作用會(huì)引起葉輪流道內(nèi)附加的水力損失；第二類(lèi)是空化引起葉片表面的壓力變化間接作用于泵的性能,空化影響葉片表面的壓力分布會(huì)造成葉片載荷分布的變化,這種葉片載荷分布的變化也會(huì)引起附加的水力損失。在空化發(fā)展的不同階段,兩類(lèi)損失對(duì)泵性能的影響不同。對(duì)泵的揚(yáng)程來(lái)說(shuō),揚(yáng)程下降初始階段和葉輪進(jìn)口的流動(dòng)狀態(tài)相關(guān),而揚(yáng)程迅速下降段和葉輪出口流動(dòng)狀態(tài)相關(guān)。 (4)空化發(fā)展到一定程度時(shí),葉輪內(nèi)的空化體積隨裝置凈正吸頭的降低而迅速增加,極低裝置凈正吸頭條件下葉輪進(jìn)口靠近口環(huán)處會(huì)出現(xiàn)空化區(qū)。葉片工作面上空化區(qū)的面積在靠近前蓋板的位置最大,工作面的空化同時(shí)也不穩(wěn)定,較易影響泵的空化性能；葉片背面上空化區(qū)末端水汽混合區(qū)的回縮導(dǎo)致的反向速度是空化不穩(wěn)定產(chǎn)生的原因。同時(shí)揭示了空化流態(tài)與泵揚(yáng)程不穩(wěn)定之間的關(guān)系：葉輪內(nèi)空化體積的增加會(huì)排擠葉輪流道,并導(dǎo)致流道進(jìn)口相對(duì)速度的增大；空化團(tuán)體積增大到一定程度會(huì)突然潰滅,造成流道過(guò)流斷面的突然增加；這種突然的過(guò)流斷面變化會(huì)造成較大的能量波動(dòng),并引起泵揚(yáng)程曲線的不穩(wěn)定。 (5)通過(guò)分析蝸殼內(nèi)能量損失隨空化的變化趨勢(shì),揭示了蝸殼的存在既影響泵的空化性能又會(huì)增加泵運(yùn)行的不穩(wěn)定。為了驗(yàn)證動(dòng)靜干涉與泵空化性能的關(guān)系,測(cè)試了4組不同外徑的葉輪并獲得了葉輪外徑的改變對(duì)泵空化性能及運(yùn)行穩(wěn)定性的影響。在此基礎(chǔ)上研究了離心泵下游幾何參數(shù)和泵空化不穩(wěn)定性之間的關(guān)系,發(fā)現(xiàn)葉輪與蝸殼隔舌的動(dòng)靜干涉強(qiáng)度是造成泵空化不穩(wěn)定性的主要原因之一。 (6)總結(jié)和分析了離心泵在非設(shè)計(jì)工況運(yùn)行時(shí),由空化導(dǎo)致的漩渦和由流量造成的失速之間的關(guān)系,指出了探索空化不穩(wěn)定和流動(dòng)不穩(wěn)定聯(lián)合作用下離心泵運(yùn)行狀態(tài)的必要性。以離心泵的揚(yáng)程駝峰曲線為例,探索了流動(dòng)不穩(wěn)定條件下離心泵的運(yùn)行狀態(tài),尋求駝峰曲線產(chǎn)生的原因并提出了可能的消除和改善駝峰曲線的辦法。初步分析了流量變化對(duì)離心泵空化不穩(wěn)定性的影響,葉輪葉片進(jìn)口沖角和流道內(nèi)的大尺度渦的相互作用決定了非設(shè)計(jì)工況下的空化性能。這些結(jié)論為后續(xù)研究空化不穩(wěn)定和流動(dòng)不穩(wěn)定聯(lián)合作用下離心泵的運(yùn)行狀態(tài)奠定基礎(chǔ)。
[Abstract]:The research work of this paper is "the cavitation characteristics and Countermeasures of hydraulic machinery" in the National Natural Science Foundation of China (51239005), the national science and technology support program "2011BAF14B04" and the Jiangsu graduate innovation fund "the unsteady flow mechanism and dynamic characteristics of the centrifugal pump cavitation." Research "(CXZZ11_0564) funding is launched.
For the current low specific speed centrifugal pump, the low efficiency is an important reason for the high cost of the pump, so the technical improvement of the low specific speed centrifugal pump has significant economic and social benefits. A very effective way to improve the pump efficiency is to increase the specific speed of the pump by increasing the speed of the pump. In this paper, the unsteady flow characteristics of centrifugal pumps are higher. This paper takes the unsteady flow characteristics of the cavitation of the blade front of the centrifugal pump as the research object, using the method of theoretical analysis, experimental research and numerical simulation, to monitor the cavitation state of the centrifugal pump, the numerical simulation of the cavitation flow, and the cavitation lead to the lift. The decline phenomenon and the influence of the downstream geometric parameters of the pump on the cavitation instability are systematically studied, and the cavitation and hump characteristics of the centrifugal pump under non design conditions are preliminarily analyzed. The main work and innovation results of this paper are as follows:
(1) the influence of grid quality on the numerical simulation accuracy of centrifugal pump is quantitatively studied. The relationship between the boundary layer grid density and the turbulence model is discussed systematically, and the evaluation mode between the boundary layer grid and the turbulence model is initially established. The advantages of the full flow model in the numerical solution of centrifugal pump are analyzed from the fluid flow angle. In this paper, the influence of regional boundary on the simulation results of non design conditions is studied. In view of the problems existing in the topology block generation and structured grid division of the calculated area, the structure grid of the centrifugal pump full flow channel based on the pump cavity integration is established and optimized.
(2) a closed test system, which can be used to test the cavitation instability of centrifugal pumps, is built to synchronize the dynamic signals of the pump performance parameters and the internal hydraulic noise of the centrifugal pump, the pressure fluctuation of the import and export, the vibration and the stator current of the motor. The 4 mathematical statistics are used, including the probability density distribution (PDF), the variance, the mean square variance and the average. The time domain information of the inlet pressure fluctuation of the impeller D2=174mm centrifugal pump is analyzed. The results show that 4 mathematical statistics methods can predict the pump head fracture condition. At the same time, the stator current analysis method of the motor is introduced. The stator current of the stator current is found by comparing and analyzing the results of the stator current in the time and frequency domain. The running state is very sensitive and can effectively monitor the cavitation state in the pump. The time domain results of the stator current can characterize the cavitation and head fracture conditions of the centrifugal pump, and the frequency domain results of the stator current can capture the primary cavitation conditions of the pump.
(3) the causes of the drop of the lift of the centrifugal pump were revealed, and the mechanism of the cavitation induced drop of the lift was preliminarily grasped, that is, the cavitation caused the pump to produce additional hydraulic loss. The hydraulic loss caused by cavitation was divided into two categories and detailed described. The first category was the change of the flow state which was induced by cavitation, that is, the direct of cavitation to the pump performance. The direct action will cause the additional hydraulic loss in the impeller flow channel; the second kind is the effect of the cavitation caused by the change of the pressure on the blade surface indirectly on the pump performance. The effect of the cavitation on the blade surface pressure distribution will cause the change of the load distribution of the blade, and the change of the load distribution of this blade will also cause additional hydraulic loss. In the different stages of cavitation development, the effect of two types of loss on pump performance is different. For the pump head, the initial stage of the head drop is related to the flow state of the impeller inlet, and the rapid drop section of the lift is related to the flow state of the impeller outlet.
(4) when the cavitation is developed to a certain extent, the cavitation volume in the impeller increases rapidly with the reduction of the net positive suction head. The cavitation area will appear at the inlet of the impeller inlet under the condition of the net positive suction of the extremely low device. The area of the cavitation area on the blade surface is the largest in the position near the front cover, and the cavitation of the working face is also unstable and is easier to shadow. The cavitation performance of the pump; the reverse velocity caused by the retraction of the water vapor mixing zone on the back of the cavitation area on the back of the blade is the cause of the instability of the cavitation. At the same time, the relationship between the cavitation flow and the instability of the pump head is revealed: the increase of the cavitation volume within the impeller will squeeze the impeller flow and lead to the increase of the inlet velocity of the inlet of the flow passage; The increase of the volume of the group to a certain extent will suddenly collapse, causing a sudden increase in the cross section of the flow channel, and this sudden change of cross section will cause greater energy fluctuation and cause the instability of the pump head curve.
(5) through the analysis of the change trend of energy loss with cavitation in the volute, it is revealed that the existence of the volute affects both the cavitation performance of the pump and the instability of the pump operation. In order to verify the relationship between the static interference and the cavitation performance of the pump, 4 groups of different outer diameter impellers are tested and the change of the outer diameter of the blade wheel is obtained for the cavitation performance and the operation stability of the pump. On the basis of this, the relationship between the geometric parameters of the downstream of the centrifugal pump and the cavitation instability of the pump is studied. It is found that the static interference intensity of the impeller and the volute is one of the main reasons for the cavitation instability of the pump.
(6) the relationship between the whirlpool caused by cavitation and the stall caused by flow is summarized and analyzed in the non design operation of centrifugal pump. The necessity of exploring the running state of the centrifugal pump under the combined effect of cavitation and flow instability is pointed out. The operation state of the pump, seeking the cause of the hump curve and the possible way to eliminate and improve the hump curve. The effect of the flow change on the cavitation instability of the centrifugal pump is preliminarily analyzed. The interaction between the inlet angle of the impeller blade and the large scale vortex in the flow channel determines the cavitation performance under the non design condition. It lays the foundation for the follow-up study of the operation of centrifugal pumps under the combined action of cavitation instability and unstable flow.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類(lèi)號(hào)】：TH311

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 張博;王國(guó)玉;張淑麗;余志毅;;修正的RNG κ-ε模型在云狀空化流動(dòng)計(jì)算中的應(yīng)用評(píng)價(jià)[J];北京理工大學(xué)學(xué)報(bào);2008年12期

2 李軍;劉立軍;李國(guó)君;豐鎮(zhèn)平;;離心泵葉輪內(nèi)空化流動(dòng)的數(shù)值預(yù)測(cè)[J];工程熱物理學(xué)報(bào);2007年06期

3 牟介剛,王樂(lè)勤;離心泵性能曲線駝峰判據(jù)的探討[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2004年04期

4 蘇永生;王永生;段向陽(yáng);;離心泵空化試驗(yàn)研究[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2010年03期

5 潘中永;倪永燕;袁壽其;李紅;;基于動(dòng)靜干涉的離心泵轉(zhuǎn)速測(cè)量機(jī)理與實(shí)驗(yàn)[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2010年03期

6 周水清;孔繁余;王志強(qiáng);易春龍;張勇;;基于結(jié)構(gòu)化網(wǎng)格的低比轉(zhuǎn)數(shù)離心泵性能數(shù)值模擬[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2011年07期

7 李曉俊;袁壽其;潘中永;劉威;駱寅;;誘導(dǎo)輪離心泵空化條件下?lián)P程下降分析[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2011年09期

8 王秀禮;袁壽其;朱榮生;付強(qiáng);俞志君;;離心泵汽蝕非穩(wěn)定流動(dòng)特性數(shù)值模擬[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2012年03期

9 李曉俊;袁壽其;潘中永;李亞林;陽(yáng)君;;離心泵邊界層網(wǎng)格的實(shí)現(xiàn)及應(yīng)用評(píng)價(jià)[J];農(nóng)業(yè)工程學(xué)報(bào);2012年20期

10 王勇;劉厚林;王健;吳賢芳;劉東喜;;離心泵葉輪進(jìn)口空化形態(tài)的試驗(yàn)測(cè)量[J];農(nóng)業(yè)機(jī)械學(xué)報(bào);2013年07期

相關(guān)博士學(xué)位論文 前1條

1 王勇;離心泵空化及其誘導(dǎo)振動(dòng)噪聲研究[D];江蘇大學(xué);2011年

，

本文編號(hào)：1987784