【摘要】：離心泵主要由葉輪和蝸殼兩大過流部件組成，共同決定著離心泵的性能。蝸殼作為離心泵的一個重要過流部件，起著重要的導(dǎo)流與擴(kuò)壓作用，其設(shè)計的好壞對泵的性能有著重大影響。而長期以來，人們往往將研究重點(diǎn)集中在葉輪上，很大程度上忽視了對蝸殼及其與葉輪匹配關(guān)系的研究。這就造成葉輪的水力性能往往非常優(yōu)異，一旦和蝸殼配合起來工作，各項(xiàng)性能指標(biāo)都會大幅度下降，并且伴隨有振動、噪聲等非穩(wěn)定工況。因此，要大幅度提高離心泵的各項(xiàng)性能指標(biāo)，必須解決葉輪與蝸殼相互匹配的問題。 本文通過改變蝸殼的進(jìn)口寬度，對蝸殼與葉輪的匹配關(guān)系進(jìn)行了數(shù)值研究。首先，本文對離心泵蝸殼的水力設(shè)計作了詳細(xì)的闡述，著重介紹了蝸殼梯形截面的計算方法，并用此方法，在保證蝸殼斷面面積不變的前提下，重新設(shè)計了兩個進(jìn)口寬度與原型泵互不相同的蝸殼，分別與原型泵葉輪組合作為本文研究所用的模型。利用FLUENT軟件對離心泵內(nèi)部流動進(jìn)行了三維定常和非定常數(shù)值模擬，計算結(jié)果較全面地揭示了三個模型各工況下全流道內(nèi)的靜壓和速度分布規(guī)律，分析了蝸殼進(jìn)口寬度對離心泵性能及蝸殼內(nèi)部壓力脈動特性的影響，并得到以下主要結(jié)論： （1）蝸殼進(jìn)口寬度對離心泵外特性的影響。三個模型的外特性預(yù)測結(jié)果表明，泵的效率和揚(yáng)程均隨蝸殼進(jìn)口寬度的增加而稍稍降低。 （2）蝸殼進(jìn)口寬度對靜壓場和速度場分布的影響。蝸殼進(jìn)口寬度的改變對流場分布也有一定的影響。同一流量下，靠近蝸殼壁面的流場高壓區(qū)域隨著蝸殼進(jìn)口寬度的增加而有所減小，從第八斷面到出口的蝸殼擴(kuò)散段，這種變化非常顯著；隨著蝸殼進(jìn)口寬度的增加，隔舌處和葉片出口的速度有所減小，蝸殼擴(kuò)散段的流場受蝸殼進(jìn)口寬度的影響也比較明顯，隨著蝸殼進(jìn)口寬度的增大，蝸殼擴(kuò)散段內(nèi)的低速區(qū)域擴(kuò)大。 （3）蝸殼進(jìn)口寬度對蝸殼斷面內(nèi)絕對速度分布的影響。蝸殼進(jìn)口寬度越大，進(jìn)口處的速度值越小，速度分布越向壁面分散，旋渦的范圍也越大。 （4）蝸殼進(jìn)口寬度對蝸殼進(jìn)口處靜壓和絕對速度分布的影響。各個流量下，總體上蝸殼進(jìn)口處的壓力隨進(jìn)口寬度增大而略有增加，而壓力波動幅度卻隨蝸殼進(jìn)口寬度增大而有所減小。各流量工況下，蝸殼進(jìn)口寬度對隔舌處的徑向速度影響相對明顯，此處的徑向速度隨著蝸殼進(jìn)口寬度增大而有所減小。 （5）蝸殼進(jìn)口寬度對蝸殼內(nèi)部壓力脈動特性的影響。蝸殼隔舌附近的壓力脈動幅度和強(qiáng)度較大，蝸殼流道內(nèi)距離隔舌越近的監(jiān)測點(diǎn)，，其壓力脈動幅度和強(qiáng)度越大。蝸殼進(jìn)口寬度的改變對蝸殼壁面和進(jìn)口處壓力脈動特性有一定的影響，總體上蝸殼進(jìn)口越寬，壓力脈動的幅度越小。
[Abstract]:Centrifugal pump mainly consists of impeller and volute, which determines the performance of centrifugal pump. Volute, as an important over-flow part of centrifugal pump, plays an important role in diversion and pressure expansion. The design of volute has a great influence on the performance of pump. For a long time, people tend to focus on the impeller and ignore the study of volute and its matching relation with impeller to a great extent. As a result, the hydraulic performance of the impeller is often very excellent. Once the impeller works together with the volute, all the performance indexes will be greatly reduced, accompanied by unstable conditions such as vibration, noise and so on. Therefore, in order to greatly improve the performance of centrifugal pump, it is necessary to solve the problem of matching impeller and volute. In this paper, the matching relationship between volute and impeller is studied by changing the inlet width of volute. Firstly, the hydraulic design of the spiral case of centrifugal pump is described in detail, and the calculation method of trapezoidal cross section of the spiral case is emphatically introduced. With this method, the cross-section area of the spiral case is not changed under the premise of keeping the cross-section area of the volute case unchanged. Two volute cases with different inlet width from that of prototype pump are redesigned, respectively, which are combined with the impeller of prototype pump as the model used in this paper. The three-dimensional steady and unsteady numerical simulation of the internal flow of centrifugal pump is carried out by using FLUENT software. The calculated results reveal the static pressure and velocity distribution in the full channel of the three models in all working conditions. The influence of volute inlet width on the performance of centrifugal pump and the pressure pulsation characteristics inside volute case are analyzed. The main conclusions are as follows: (1) the influence of volute inlet width on external characteristics of centrifugal pump. The prediction results of the external characteristics of the three models show that the efficiency and head of the pump decrease slightly with the increase of the inlet width of the volute. (2) the influence of volute inlet width on the distribution of static pressure field and velocity field. The change of the inlet width of the volute also has a certain effect on the distribution of the flow field. At the same flow rate, the high pressure flow field near the wall of the volute case decreases with the increase of the inlet width of the volute, and this change is very significant in the diffusion section from the eighth section to the outlet. With the increase of the inlet width of the volute, the velocity of the diaphragm and the outlet of the blade decreases, and the flow field in the diffusion section of the volute is also influenced by the width of the inlet of the volute, and with the increase of the width of the inlet of the volute, The low-speed region in the diffusion section of the volute is enlarged. (3) the influence of inlet width of volute on the distribution of absolute velocity in the section of volute. The larger the inlet width of the volute is, the smaller the velocity value at the inlet is, the more dispersed the velocity distribution is towards the wall, and the larger the scope of the vortex is. (4) the influence of the inlet width of the volute on the static pressure and absolute velocity distribution at the inlet of the volute. At each flow rate, the pressure at the inlet of the volute increases slightly with the increase of the inlet width, while the amplitude of the pressure fluctuation decreases with the increase of the inlet width of the volute. Under various flow conditions, the inlet width of the volute has a relatively obvious effect on the radial velocity at the tongue partition, and the radial velocity here decreases with the increase of the inlet width of the volute. (5) the influence of the inlet width of the volute on the pressure fluctuation characteristics of the volute. The pressure fluctuation amplitude and intensity near the volute septum is larger, and the closer the volute passage is to the diaphragm, the greater the pressure fluctuation amplitude and strength are. The variation of the inlet width of the volute has a certain effect on the pressure fluctuation characteristics at the wall and inlet of the volute. Generally, the wider the inlet of the volute case is, the smaller the amplitude of the pressure fluctuation is.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH311

【引證文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 吳登昊;高效低振動循環(huán)泵設(shè)計與試驗(yàn)研究[D];江蘇大學(xué);2013年

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