發(fā)布時間：2018-07-27 12:52

【摘要】：在工程實際中,離心泵變工況運轉非常常見,而在離心泵調節(jié)工況的諸多方法中,調速調節(jié)的節(jié)能優(yōu)勢是非常明顯的。這就需要我們研究當離心泵轉速變化時,其內部流場和性能參數的變化情況,以完善現(xiàn)有的半經驗理論,更好指導實際生產。同時,對于一些大功率離心泵,由于實驗室容量、驅動原動機功率等各種條件的限制,不能按規(guī)定轉速進行全速性能試驗,只能采用降速試驗,然后再通過比例定律將降速測量參數換算為規(guī)定轉速的參數,這時,比例定律的準確與否將起著至關重要的作用,所以有必要對比例定律進行驗證,以確定其準確性和適用范圍,為實際的應用提供參考。 為此,本文選用實際中使用廣泛的單級雙吸離心泵為研究對象,通過數值模擬的方法,對其8個不同轉速所對應的5組相似工況下的內部流場及外特性進行了對比研究,并計算了離心泵調速調節(jié)的節(jié)能效果。本文主要的研究成果如下: 1.建立了雙吸離心泵的三維模型,并進行了網格劃分,將畫好網格的模型導進Fluent軟件中,對其進行了全流道三維數值模擬。 2.對模擬結果進行了后處理,得到了壓水室和葉片正面、背面的壓力和速度分布云圖,通過對比壓力云圖發(fā)現(xiàn),在相似工況點上,離心泵壓水室、葉片正面和背面的壓力分布非常相似,近乎完全相同,說明本文所研究的泵在相似工況下內部流場可以實現(xiàn)動力相似,同時也說明本文的流場計算是基本正確的;通過對比速度云圖發(fā)現(xiàn), 0.7n、0.9n、1n、1.1n、1.2n、1.3n下的相似工況點上壓水室內的速度分布近乎完全相同,而在0.6n、0.8n下的相似工況點上,壓水室內的速度分布在擴散管處和另外6個相似工況點略有不同,葉片正面和背面的速度分布則規(guī)律非常相似。總體來看,速度分布在葉片上和壓水室內的變化規(guī)律還是高度相似的,說明各相似工況點上的流動可以滿足運動相似。 3.通過數值模擬的結果預測了泵在不同轉速下的性能參數,然后和比例定律的計算結果進行了比較,發(fā)現(xiàn)在0.6n～1.3n的轉速變化范圍以內,比例定律能較好的預測泵的性能參數隨轉速的變化情況,對本文所選的5組相似工況點,比例定律計算誤差大多在1%以內,可以滿足實際需要。 4.分析了調速調節(jié)的節(jié)能原理和影響調速調節(jié)節(jié)能效果的因素,并計算了泵在特定管網下的節(jié)能效果。通過計算發(fā)現(xiàn),使用調速調節(jié)具有良好的節(jié)能效果,隨著調節(jié)量的增加,調速調節(jié)的節(jié)能效果也越明顯,當在低流量下運行時,節(jié)能率可達74.58%。
[Abstract]:In engineering practice, it is very common for centrifugal pump to operate under different working conditions, but the energy-saving advantage of speed regulation is very obvious in many methods of centrifugal pump regulation. It is necessary for us to study the variation of internal flow field and performance parameters when the speed of centrifugal pump changes in order to improve the existing semi-empirical theory and better guide the actual production. At the same time, for some high power centrifugal pumps, due to the limitation of laboratory capacity, driving prime mover power and other conditions, the full-speed performance test can not be carried out according to the specified rotational speed. Then through the law of proportion, the parameters of the deceleration measurement are converted to the parameters of the specified rotational speed. At this time, the accuracy of the law of proportion will play an important role, so it is necessary to verify the law of proportion. In order to determine its accuracy and scope of application, to provide a reference for practical applications. In this paper, a single stage double suction centrifugal pump, which is widely used in practice, is chosen as the research object. Through the method of numerical simulation, the internal flow field and external characteristics of five groups of similar working conditions corresponding to 8 different rotational speeds are compared and studied. The energy-saving effect of speed regulation of centrifugal pump is calculated. The main research results of this paper are as follows: 1. The three-dimensional model of double suction centrifugal pump is established, and the mesh is divided. The model of drawing mesh is introduced into Fluent software, and the 3D numerical simulation of the whole flow channel is carried out. 2. After post-processing of the simulation results, the pressure and velocity distributions of the water pressure chamber and the front and back of the blade are obtained. By comparing the pressure cloud images, it is found that at similar working conditions, the centrifugal pump pressure chamber, The pressure distribution on the front and back sides of the blade is very similar, almost identical, which indicates that the internal flow field of the pump studied in this paper can achieve dynamic similarity under similar working conditions, and the calculation of the flow field in this paper is basically correct. By comparing the velocity cloud diagram, it is found that the velocity distribution of the water pressure chamber is almost identical at the similar working condition points under 0.7 ng ~ (0.9n) ~ (-1) n ~ (-1) ~ (-1) N ~ (-1) ~ (-1) ~ (-1) N ~ (-1), but the velocity distribution of the water pressure chamber is slightly different between the diffuser tube and the other six similar working conditions at the similar working condition point under 0.6n ~ 0.8n. The velocity distribution on the front and back of the blade is very similar. As a whole, the variation of velocity distribution on the blade and the water pressure chamber is highly similar, which indicates that the flow at the same working conditions can satisfy the movement similarity. The performance parameters of the pump at different rotational speeds are predicted by the numerical simulation results, and then compared with the calculation results of the law of scale. It is found that the speed of 0.6n~1.3n is within the range of variation. The law of proportion can better predict the variation of pump performance parameters with rotational speed. For the five similar working conditions selected in this paper, the error of the law of proportion calculation is mostly within 1%, which can meet the actual needs. 4. The energy saving principle of speed regulation and the factors influencing the energy saving effect of speed regulation are analyzed, and the energy saving effect of pump under special pipe network is calculated. Through calculation, it is found that the speed regulation has good energy saving effect. With the increase of the regulating quantity, the energy saving effect of the speed regulation is more obvious. When running under the low flow rate, the energy saving rate can reach 74.58.
【學位授予單位】：蘭州理工大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TH311

【引證文獻】

相關碩士學位論文 前1條

1 史佩琦;不同葉型的半開式葉輪離心泵的數值模擬與試驗研究[D];浙江理工大學;2012年

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本文編號：2147892