本文選題：高速泵　切入點：復合葉輪　出處：《揚州大學》2017年碩士論文　論文類型：學位論文

【摘要】：低比轉速高速離心泵具有小流量、高揚程、結構緊湊等特點,被廣泛應用于石油化工、航空航天等領域。但因其轉速高,所以其內部流動與常見離心泵存在較大差異,如:在葉片吸力面易產(chǎn)生尾跡流,而壓力面易出現(xiàn)射流等。高速泵的內外特性研究—直是流體機械領域重點研究課題。本文結合流量Qd=10m3/h、揚程H=410m、轉速n = 8500r/min,比轉速ns=18的高速泵的復合葉輪、蝸殼、誘導輪水力設計,利用三維湍流數(shù)值模擬方法,基于ANSYS CFX軟件平臺,對設計的高速離心泵進行全流道三維定常和非定常仿真計算,探索了高速離心泵內外特性的規(guī)律。研究得出了葉輪、蝸殼和誘導輪內的速度、壓力分布特征,數(shù)值模擬預測水泵的外特性以及隔舌處的壓力脈動特性。主要工作如下:(1)利用速度系數(shù)法和加大流量法,設計了流量Qd=10m3/h、揚程H = 410m、轉速n = 8500r/min,比轉速ns=18的高速泵的復合葉輪、蝸殼和等螺距誘導輪。(2)利用PRO/E和GAMBIT軟件對離心泵的進水管、復合葉輪、蝸殼及等螺距誘導輪等過流部件進行三維建模,運用非結構化網(wǎng)格離散過流部件計算域。(3)為探求轉速變化對離心泵內部流動影響,基于雷諾時均N-S控制方程和標準的k-ε湍流模型,利用ANSYSCFX軟件,數(shù)值模擬了設計流量下6種不同轉速的水泵內部流動,比較分析了轉速對葉輪內靜壓和相對速度分布規(guī)律的影響。(4)針對設計轉速n = 8500r/min,數(shù)值模擬離心泵高速運行在小流量0.4Qd、設計流量1.0Qd和大流量1.3Qd三種工況下的內外特性,研究得到了不同流量下復合葉輪內部壓力場、速度場及蝸殼隔舌處的靜壓力場分布,數(shù)模預測高速泵的能量特性。(5)對帶前置誘導輪的高速離心泵進行了三維定常數(shù)湍流值模擬,得出了小流量0.4Qd、設計流量1.0Qd和大流量1.3Qd三種工況的內外特性,對比了不同流量下誘導輪、葉輪的靜壓場和相對速度場分布;分析了前置誘導對水泵能量特性的影響。(6)數(shù)值模擬了帶前置誘導輪的高速離心泵蝸殼與葉輪耦合非定常流動,得到了蝸殼隔舌處3個不同監(jiān)測點,在小流量0.4Qd、設計流量1.0Qd和大流量1.3Qd三種工況下的壓力脈動規(guī)律,對比分析了它們的時域特性和頻域特性。(7)數(shù)值模擬了帶前置誘導輪的高速離心泵葉輪葉柵及子午面上的空化情況,并就偏離設計點工況下誘導輪對泵汽蝕余量的影響進行了預測。
[Abstract]:Low specific speed and high speed centrifugal pump is widely used in petrochemical, aerospace and other fields because of its small flow rate, high head and compact structure. However, because of its high speed, its internal flow is quite different from that of common centrifugal pump. For example, wake flow is easily produced on the suction surface of the blade, The internal and external characteristics of high speed pump is a key research topic in fluid machinery field. In this paper, the hydraulic design of compound impeller, volute and induction wheel of high speed pump with flow rate QD 10m / h, head H = 410m, rotational speed n = 8500rr / min, specific speed ns=18, is introduced. Based on the ANSYS CFX software platform, the three-dimensional steady and unsteady simulation of the designed high-speed centrifugal pump is carried out by using the three-dimensional turbulent numerical simulation method, and the internal and external characteristics of the high-speed centrifugal pump are explored, and the impeller is obtained. The velocity, pressure distribution, numerical simulation and prediction of the external characteristics of the pump and the pressure pulsation of the tongue in the volute and the inducer wheel. The main work is as follows: 1) using the velocity coefficient method and the method of increasing the flow rate, The compound impeller of high speed pump with specific speed ns=18, volute and equal pitch inducer are designed by using PRO/E and GAMBIT software. The inlet pipe and compound impeller of centrifugal pump are designed by using PRO/E and GAMBIT software, the flow rate is 10m3 / h, the head H = 410m, the rotational speed n = 8500rr / min, the compound impeller of high speed pump with specific speed ns=18. The three-dimensional model of volute and equal pitch inducer is used to study the effect of speed change on the flow in centrifugal pump by using unstructured grid discrete flow unit. Based on the Reynolds time-averaged N-S governing equation and the standard k- 蔚 turbulence model, the internal flow of the pump with six different rotational speeds under the designed flow rate is numerically simulated by using ANSYSCFX software. This paper compares and analyzes the influence of rotating speed on the static pressure and relative velocity distribution of impeller. According to the design speed n = 8500 r / min, the numerical simulation of the internal and external characteristics of centrifugal pump under three working conditions: small flow rate 0.4Qd, design flow rate 1.0Qd and large flow rate 1.3Qd, is carried out. The internal pressure field, velocity field and static pressure field distribution at the tongue of the volute are obtained at different flow rates. The numerical model is used to predict the energy characteristics of the high speed pump. (5) the three dimensional constant turbulence value of the high speed centrifugal pump with the leading inducer is simulated. The internal and external characteristics of small flow rate 0.4Qd, design flow rate 1.0Qd and large flow rate 1.3Qd are obtained, and the distribution of static pressure field and relative velocity field of induction wheel and impeller under different flow rates are compared. The influence of leading inducement on pump energy characteristics is analyzed. Numerical simulation of the coupling unsteady flow between volute and impeller of high speed centrifugal pump with leading inductor wheel is carried out, and three different monitoring points at the tongue of volute are obtained. When the flow rate is 0.4Qd, the pressure fluctuation law is obtained under three working conditions, namely, the design flow rate of 1.0Qd and the large flow rate of 1.3Qd. The numerical simulation of cavitation on the cascade and meridian of high speed centrifugal pump impeller with leading inducer is carried out by comparing their time-domain and frequency-domain characteristics. The influence of the inducer on the cavitation margin of the pump is forecasted when it deviates from the design point.
【學位授予單位】：揚州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TH311

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