【摘要】：隨著計(jì)算機(jī)科學(xué)及流體力學(xué)理論的發(fā)展，CFD技術(shù)已經(jīng)廣泛應(yīng)于用離心泵性能預(yù)測與內(nèi)部流動研究。但目前在進(jìn)行離心泵性能預(yù)測時，往往采用簡化的模型，忽略了口環(huán)間隙及泵腔對離心泵性能的影響，這樣就造成了預(yù)測結(jié)果的誤差。實(shí)際上，水泵中的泄漏是不可避免的，而且口環(huán)間隙作為一種非接觸式密封形式，可以保持較小的泄漏損失，對研究離心泵的容積損失及內(nèi)部流動結(jié)構(gòu)有著十分重要的意義。 本文以一臺單級單吸懸臂離心油泵為主要模型，該原型泵包含平衡孔。首先利用CFD技術(shù)對整體流道模型和簡化模型進(jìn)行三維流場數(shù)值模擬，預(yù)測了兩種模型的的性能曲線，并與試驗(yàn)曲線進(jìn)行對比，，驗(yàn)證離心泵整體模型的數(shù)值模擬計(jì)算與試驗(yàn)數(shù)據(jù)更為貼近，為后期研究口環(huán)間隙中流動對離心泵性能的影響奠定基礎(chǔ)。之后本文基于CFD的數(shù)值模擬方法，通過建立不同口環(huán)間隙的離心泵實(shí)體模型對性能進(jìn)行詳盡的分析，對比前、后口環(huán)間隙大小的變化對離心泵外特性及內(nèi)部流動情況的影響。通過數(shù)值模擬結(jié)果的分析，初步探討了口環(huán)間隙變化后，泵腔內(nèi)液體流動的情況；文中還通過對比不同口環(huán)間隙的泄漏量隨流量的變化，分析口環(huán)間隙改變后口環(huán)間隙進(jìn)出口壓差、泄漏量、流量變化的關(guān)系；以及分析葉輪蓋板的壓力變化情況，并計(jì)算不同口環(huán)間隙的離心泵的軸向力及徑向力。在進(jìn)行了上述研究后，得到以下結(jié)論： 1）整體模型的數(shù)值模擬預(yù)測的離心泵性能曲線與試驗(yàn)曲線趨勢相近，簡化模型對比試驗(yàn)曲線的誤差較大，證明整體模型數(shù)值模擬結(jié)果的可靠性。同時對整體模型內(nèi)部流動進(jìn)行分析，發(fā)現(xiàn)原型泵水力設(shè)計(jì)存在一定問題。 2）對加大口環(huán)間隙的模型進(jìn)行數(shù)值模擬后，所得的設(shè)計(jì)工況參數(shù)均發(fā)生變化，且水泵的性能明顯差于原型泵。 3）口環(huán)間隙值的改變，影響泵腔內(nèi)液體的壓力及速度分布。 4）口環(huán)間隙內(nèi)泄漏量的改變與間隙值的大小有直接關(guān)系，且泄漏量的大小影響了軸向力的變化，但對徑向力影響不大。 因此，離心泵在進(jìn)行建模及數(shù)值計(jì)算時須考慮口環(huán)間隙，口環(huán)間隙中的流動非常復(fù)雜且影響離心泵的性能及內(nèi)部流動情況。本文研究結(jié)果為口環(huán)間隙大小的合理設(shè)計(jì)及離心泵性能預(yù)測提供參考，且為改善和提高離心泵性能奠定了基礎(chǔ)。
[Abstract]:With the development of computer science and hydrodynamics theory, CFD technology has been widely used in centrifugal pump performance prediction and internal flow research. But at present, the simplified model is used to predict the performance of centrifugal pump, and the influence of the clearance of the ring and the cavity of the pump on the performance of the centrifugal pump is ignored, which results in the error of the prediction result. In fact, the leakage in the pump is inevitable, and as a non-contact seal, the gap of the orifice ring can keep a small leakage loss, which is of great significance to the study of the volume loss and the internal flow structure of the centrifugal pump. In this paper, a single-stage single-suction cantilever centrifugal oil pump is used as the main model. The prototype pump contains a balance hole. Firstly, the 3-D flow field of the whole channel model and the simplified model are simulated by using CFD technology, and the performance curves of the two models are predicted and compared with the experimental curves. It is proved that the numerical simulation calculation of the whole model of centrifugal pump is closer to the experimental data, which lays a foundation for the later study of the effect of the flow in the clearance of the orifice ring on the performance of the centrifugal pump. Then, based on the numerical simulation method of CFD, the performance of centrifugal pump is analyzed in detail by establishing the solid model of centrifugal pump with different orifice clearance. Before the comparison, the influence of the size of the clearance on the external characteristics and internal flow of centrifugal pump is discussed. Through the analysis of the numerical simulation results, the flow of liquid in the pump cavity after the change of the gap between the orifice and the ring is discussed preliminarily. In this paper, the relationship among the pressure difference, leakage volume and flow rate of the inlet and outlet of the gap after the change of the gap is analyzed by comparing the leakage volume of the different ring gap with the flow rate. The pressure variation of impeller cover plate is analyzed and the axial and radial forces of centrifugal pump with different clearance are calculated. After the above research, the following conclusions are obtained: 1) the performance curve of centrifugal pump predicted by numerical simulation of the whole model is similar to that of the test curve, and the error between the simplified model and the test curve is large. The reliability of the numerical simulation results of the whole model is proved. At the same time, the internal flow of the whole model is analyzed, and it is found that there are some problems in the hydraulic design of the prototype pump. 2) after numerical simulation of the model, the design parameters of the pump are all changed, and the performance of the pump is obviously worse than that of the prototype pump. 3) the pressure and velocity distribution of the liquid in the pump cavity is affected by the change of the gap value. 4) the change of leakage amount in the gap is directly related to the value of the gap, and the magnitude of the leakage affects the change of axial force, but not the radial force. Therefore, the clearance of the orifice ring should be taken into account in the modeling and numerical calculation of the centrifugal pump. The flow in the clearance of the orifice ring is very complex and affects the performance and internal flow of the centrifugal pump. The results of this paper provide a reference for the reasonable design of the clearance between the orifice ring and the performance prediction of the centrifugal pump, and lay a foundation for improving and improving the performance of the centrifugal pump.
【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

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