本文關(guān)鍵詞： 高比轉(zhuǎn)數(shù)離心泵 葉片出口角 非定常流動(dòng) 結(jié)構(gòu)動(dòng)力特性 流固耦合　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：高比轉(zhuǎn)數(shù)離心泵是指比轉(zhuǎn)數(shù)為150~300的離心泵,多應(yīng)用于航天工程、電力工程、化學(xué)化工等領(lǐng)域。本文針對(duì)某一型號(hào)高比轉(zhuǎn)數(shù)化工流程離心泵的設(shè)計(jì)優(yōu)化展開(kāi)相關(guān)研究工作,并得到校創(chuàng)新人才協(xié)同培養(yǎng)項(xiàng)目(XTPY201618)的資助�；ち鞒瘫檬腔どa(chǎn)裝置中的重要基礎(chǔ)設(shè)施,也是使用量最大的旋轉(zhuǎn)機(jī)械,在化工流程中起著關(guān)鍵性作用。近年來(lái),隨著社會(huì)經(jīng)濟(jì)發(fā)展,型式單一、運(yùn)行穩(wěn)定性差、耗能高的化工流程泵已經(jīng)滿足不了未來(lái)工業(yè)4.0的要求。離心泵的運(yùn)行效率很大程度上由關(guān)鍵過(guò)流部件尤其是葉輪水力設(shè)計(jì)決定的,而目前針對(duì)研究葉片主要幾何參數(shù)對(duì)泵內(nèi)部流動(dòng)特性及結(jié)構(gòu)動(dòng)力特性的影響規(guī)律研究還不夠全面和深入。某公司從經(jīng)濟(jì)效益最大化出發(fā),要求在不改變主體結(jié)構(gòu)的前提下僅對(duì)葉片重新設(shè)計(jì)優(yōu)化以提高水力效率。因此,本文著眼于葉片出口角這一關(guān)鍵參數(shù),從其對(duì)外特性、內(nèi)流場(chǎng)以及結(jié)構(gòu)動(dòng)力特性等多方面特征來(lái)揭示其影響規(guī)律和機(jī)理。本文主要的研究?jī)?nèi)容及創(chuàng)新點(diǎn)有:1.以一臺(tái)高比轉(zhuǎn)數(shù)化工流程離心泵為研究對(duì)象,在原型泵的基礎(chǔ)上保證其他幾何參數(shù)不變,設(shè)計(jì)了4個(gè)葉片出口角(17°、27°、37°、47°)的葉輪方案,并對(duì)不同方案進(jìn)行了多工況下的非定常數(shù)值模擬。通過(guò)外特性對(duì)比分析,可以發(fā)現(xiàn):隨著葉片出口角的增大,額定工況下?lián)P程增加,這是由于出口圓周速度隨葉片出口角的增大而增大,結(jié)合泵基本方程,不難發(fā)現(xiàn)揚(yáng)程隨出口圓周速度的增大而增大,但如果葉片出口角過(guò)大,則會(huì)導(dǎo)致葉片彎曲嚴(yán)重,出現(xiàn)“S”形,流道明顯變短,相鄰葉片間的擴(kuò)散角變大,導(dǎo)致水力損失增大,效率也會(huì)明顯下降,尤其是在大流量工況下表現(xiàn)更明顯。將原型泵重復(fù)性較好的外特性試驗(yàn)數(shù)據(jù)與數(shù)值模擬預(yù)測(cè)值對(duì)比,可以驗(yàn)證研究中流體域模型構(gòu)建正確,數(shù)值模擬方法可靠。2.為了更明顯地呈現(xiàn)對(duì)比分析結(jié)果,從而能更直觀地掌握葉片出口角對(duì)化工流泵內(nèi)部流動(dòng)特性的影響,僅針對(duì)新設(shè)計(jì)的4個(gè)葉輪模型進(jìn)行內(nèi)部非定常流動(dòng)特性分析,通過(guò)分析葉輪中截面上的靜壓分布,湍動(dòng)能與速度矢量分布,正則化螺旋度分布以及小流量工況下葉輪軸面上的回流特性,以揭示葉片出口角在不同工況下對(duì)內(nèi)部流動(dòng)特性的影響規(guī)律。研究表明:隨著葉片出口角增大,葉輪進(jìn)口的低壓流體區(qū)域逐漸向出口方向擴(kuò)散,在葉片工作面附近存在逆壓梯度并有不穩(wěn)定的低壓流體聚集,容易發(fā)生流動(dòng)分離;葉片出口角過(guò)大時(shí),湍動(dòng)能整體偏大,所帶來(lái)的軸向漩渦有所擴(kuò)大,尤其是對(duì)大流量工況而言,近乎擴(kuò)大到整個(gè)流道;小流量工況下的正則化螺旋度最大,意味著流動(dòng)容易失穩(wěn),從而會(huì)產(chǎn)生不穩(wěn)定流動(dòng)結(jié)構(gòu),回流現(xiàn)象隨葉片出口角的增大而有所加劇,并且主要是在靠近前后蓋板面上發(fā)生回流,這個(gè)現(xiàn)象和正則化螺旋度預(yù)測(cè)的失穩(wěn)特征相吻合;葉片出口角為47°的葉輪中截面上的螺旋度分布出現(xiàn)紊亂現(xiàn)象,同時(shí),既有正向漩渦也有逆向漩渦產(chǎn)生,且強(qiáng)度較大,這可能是由于葉片出口角增大導(dǎo)致葉輪掃掠的尾跡區(qū)有所增大引起的。3.對(duì)比分析4個(gè)方案多工況下的壓力脈動(dòng)以及葉輪所受徑向力分布,以揭示葉片出口角對(duì)泵內(nèi)部非定常流動(dòng)特性的影響規(guī)律。研究結(jié)果表明:在1.0Q工況下,壓力脈動(dòng)幅度隨葉片出口角增大而增大,但脈動(dòng)主頻沒(méi)有發(fā)生變化,說(shuō)明產(chǎn)生壓力脈動(dòng)的主要因素還是葉片與隔舌的動(dòng)靜干涉作用;大流量工況下的壓力脈動(dòng)明顯比小流量工況下的要?jiǎng)×?且幅值普遍較大;隨著葉片出口角增大,次主頻有向低頻處移動(dòng)的趨勢(shì),說(shuō)明葉片出口角對(duì)流動(dòng)結(jié)構(gòu)有影響,從而對(duì)壓力造成了一定影響。對(duì)4個(gè)方案在不同工況下計(jì)算葉輪所受徑向力分析可知:葉輪所受徑向力均是在額定工況下受力最小;葉片出口角對(duì)小流量工況下的徑向力分布影響最大;一定程度上減小葉片出口角能夠有效改善作用在葉輪上的徑向力分布。4.為全面揭示葉片出口角對(duì)泵結(jié)構(gòu)動(dòng)力特性的影響規(guī)律,首次基于雙向流固耦合作用下對(duì)各方案進(jìn)行額定工況下的數(shù)值計(jì)算。對(duì)比分析了流固耦合作用前后預(yù)測(cè)的揚(yáng)程值,可以發(fā)現(xiàn)流固耦合作用下預(yù)測(cè)值比非流固耦合作用下預(yù)測(cè)值低,但模擬誤差明顯減小了;對(duì)比分析交界線的等效應(yīng)力分布,結(jié)果表明:葉片出口角對(duì)葉片背面與前后蓋板交界線上的等效應(yīng)力分布影響不大,而對(duì)葉片工作面與前蓋板交界線在0.6倍出口到0.8倍出口位置以及葉片工作面與后蓋板交界線在0.8倍出口到出口位置影響很大,并且等效應(yīng)力會(huì)隨葉片出口角的增大而增大;此外還發(fā)現(xiàn)在出口附近均出現(xiàn)了應(yīng)力集中現(xiàn)象;對(duì)比分析額定工況下4個(gè)葉輪的計(jì)算變形量可以發(fā)現(xiàn):適當(dāng)減少葉片出口角有助于減少變形量,改善葉輪變形分布情況;對(duì)比分析葉輪最大等效應(yīng)力,表明:葉片出口角過(guò)大,會(huì)導(dǎo)致最大等效應(yīng)力偏大,過(guò)小則會(huì)帶來(lái)較大幅度的交替動(dòng)載荷;流固耦合作用下的葉輪結(jié)構(gòu)動(dòng)力特性研究表明:4個(gè)方案下的葉輪第一階固有頻率遠(yuǎn)大于1倍葉頻,同時(shí)也避開(kāi)了二次諧波和三次諧波頻率,葉片出口角選取較大時(shí),有助于提高固有頻率,但過(guò)大則會(huì)導(dǎo)致振型較大幅度的擺動(dòng)和扭動(dòng),較小時(shí)可以使得變形量分布更為均勻。
[Abstract]:High speed centrifugal pump is a specific speed centrifugal pump 150~300, widely used in aerospace engineering, electrical engineering, chemical engineering and other fields. The design optimization for a certain type of high specific speed centrifugal pump in chemical process to carry out relevant research work, and collaborative innovation talent training project school (XTPY201618) of China. The chemical process pump is an important infrastructure in chemical plant, is the largest amount of rotating machinery, plays a key role in the chemical process. In recent years, with the development of social economy, the type of single operation, poor stability, high energy consumption of chemical process pumps have been unable to meet the future requirement for industry 4. The running efficiency of the centrifugal pump greatly the extent to which the key flow components especially decided hydraulic design of impeller, and the main geometric parameters on the blade of the pump internal flow characteristics and the dynamic characteristics of the structure. Sound rules are not comprehensive and thorough research. A company from the point of economic benefit maximization, requirements without changing the main structure only on leaf re design optimization to improve hydraulic efficiency. Therefore, this paper focuses on the key parameters of blade outlet angle, from its external characteristics, internal flow field and the dynamic characteristics of the structures. The characteristics to reveal its mechanism and influence. The contents of this paper and the main innovations are: 1. with a high specific speed centrifugal pump in chemical process as the research object, guarantee the other geometric parameters unchanged in the prototype pump, the design of the 4 blade outlet angle (17 degrees, 27 degrees, 37 degrees. 47 DEG) of the impeller scheme, and the different schemes are unsteady numerical simulation under various conditions. Through the comparative analysis of characteristics, can be found: with the increase of blade outlet angle, rated head increased, this is due to the circumferential speed of export With the blade outlet angle increases with the pump, the basic equations, it is not difficult to find increased lift with export circumferential speed increases, but if the blade outlet angle is too large, it will lead to serious curved blade, the shape of "S" appears, the channel becomes shorter between adjacent blades and the diffusion angle becomes larger, lead to increased water loss, the efficiency will be significantly decreased, especially in the large flow condition become more obvious. The simulation data repeatability characteristics and good numerical prototype pump can verify the predictive value of contrast, research the fluid domain model constructed correctly, the numerical simulation method is reliable for.2. more obvious comparative analysis results thus, more intuitive grasp of the effect of blade outlet angle on the chemical flow characteristics inside the pump impeller, only for the 4 new design model of internal unsteady flow characteristic analysis, through the analysis of the static impeller in cross section The distribution of pressure, turbulent kinetic energy and velocity distribution, flow characteristics on the surface of the impeller shaft normalized helicity distribution and small flow rate condition, in order to reveal the blade outlet angle influence on the internal flow characteristics under different conditions. The results show that: with the increase of impeller blade outlet angle, low pressure fluid region gradually to the export import the direction of diffusion, in the vicinity of the working surface of blade are adverse pressure gradient and low pressure fluid instability prone to aggregation, flow separation; blade outlet angle is too large, the larger the turbulent kinetic energy, the axial vortex caused by increased, especially for the large flow condition, almost expanded to the entire channel; small flow condition the normalized helicity maximum, mean flow is easy to instability, which will produce unstable flow structure, the backflow phenomenon with increasing blade outlet angle and has intensified, and mainly in the near front Recirculation cover surface, this phenomenon and regular instability characteristics of helicity prediction coincide; blade outlet angle spiral impeller is 47 degrees in the degree distribution disorder phenomenon, at the same time, both have positive vortex vortex generation and reverse, greater intensity, which may be due to blade outlet angle increase in the analysis increases contrast caused by.3. is in the wake of impeller sweep 4 schemes under various conditions of pressure pulsation and impeller radial force distribution, in order to reveal the outlet blade angle on the pump internal unsteady flow characteristics influence. The research results show that: in the condition of 1.0Q, and increase the amplitude of pressure fluctuation with the blade outlet angle increases, but the pulsation frequency did not change, the main factors of the pressure pulsation or blade and the tongue of the rotor stator interaction; pressure pulsation under large flow condition is higher than that of small flow conditions To be intense, and the amplitude is generally larger; with the increase of blade outlet angle, time frequency shift to the low frequency trend, indicating blade outlet angle on the flow structure, thus affects the pressure on the 4 schemes under different conditions in the calculation of impeller radial force analysis shows that: the radial impeller are under rated condition the minimum force; blade outlet angle distribution of the radial force of the small flow rate condition the greatest impact; to some extent reduce blade outlet angle can effectively improve the effect of radial force on the impeller to fully reveal the influence of the distribution of.4. blade outlet angle on the dynamic characteristics of pump structure, function for the first time the two-way flow solid coupling under numerically under the rated conditions of each scheme were analyzed and compared. Based on the calculation of the fluid solid coupling effect prediction of the lift value, can be found under the action of fluid solid coupling predictive value than the non fluid solid coupling By the prediction value is low, but the simulation error is significantly reduced; comparative analysis of equivalent boundary stress distribution, the results show that the equivalent blade angle on the back of the blade and the front cover plate at the junction of the stress distribution has little effect on the working surface of blade and the front cover of the demarcation line in 0.6 times to 0.8 times the export export the position and the blade working surface and the back boundary line in 0.8 times exports to position a great impact, and the equivalent stress increases with the blade outlet angle; in addition, the stress concentration phenomenon appeared near the exit; calculation on the rated condition of 4 impeller deformation can be found: reduce the blade outlet angle helps reduce deformation, improve the deformation distribution of the impeller impeller; comparative analysis shows that the maximum equivalent stress, blade outlet angle is too large, will cause the maximum equivalent stress is too large, too small will The dynamic load brought alternating greatly; flow dynamic characteristics of impeller structure and solid coupling show that the impeller the first 4 order natural frequency under the program is far greater than 1 times the frequency of leaf, while also avoiding the two harmonic and three harmonic frequency, select the blade outlet angle is larger, is helpful to improve the natural frequency however, too large will cause vibration greatly swing and twisting, smaller deformation can make the distribution more uniform.

【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ051.21

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