本文關(guān)鍵詞：低比轉(zhuǎn)速?gòu)?fù)合葉輪離心泵非定常流場(chǎng)的數(shù)值模擬　出處：《浙江理工大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 離心泵 低比轉(zhuǎn)速 復(fù)合葉輪 非定常 數(shù)值模擬

【摘要】：離心葉輪是低比轉(zhuǎn)速離心泵的主要過(guò)流部件之一，其作用是將原動(dòng)機(jī)的機(jī)械能直接傳給流體，以提高液體的靜壓能和動(dòng)壓能，因此葉輪的結(jié)構(gòu)對(duì)離心泵內(nèi)部流場(chǎng)及性能有著至關(guān)重要的作用。對(duì)此，本文基于三維N-S方程和RNG k-ε湍流模型對(duì)具有4葉片普通葉輪、8葉片和12葉片復(fù)合葉輪的三臺(tái)低比轉(zhuǎn)速離心泵進(jìn)行了非定常數(shù)值模擬，并進(jìn)行了外特性性能試驗(yàn)測(cè)試。主要研究?jī)?nèi)容如下： 采用PRO/E三維造型軟件對(duì)4葉片、8葉片和12葉片葉輪低比轉(zhuǎn)速離心泵進(jìn)行三維整機(jī)全流場(chǎng)造型，并用CFD軟件FLUENT對(duì)其內(nèi)部流動(dòng)進(jìn)行了數(shù)值模擬，分析了不同時(shí)刻3臺(tái)離心泵內(nèi)部的速度場(chǎng)和壓力場(chǎng)；此外，在蝸殼具有代表性的四個(gè)斷面的壁面附近以及蝸舌部位設(shè)置了監(jiān)測(cè)點(diǎn)，對(duì)蝸殼壁面附近的壓力脈動(dòng)進(jìn)行了分析；最后，對(duì)三臺(tái)低比轉(zhuǎn)速離心泵的外特性性能進(jìn)行了數(shù)值預(yù)測(cè)和試驗(yàn)測(cè)試，并將數(shù)值結(jié)果和試驗(yàn)結(jié)果進(jìn)行了對(duì)比。經(jīng)過(guò)分析，得出了以下結(jié)論： (1)針對(duì)數(shù)值模擬得到的3個(gè)葉輪內(nèi)部不同時(shí)刻的速度場(chǎng)進(jìn)行了分析，發(fā)現(xiàn)由于普通葉輪中沒(méi)有布置分流葉片，相鄰長(zhǎng)葉片間流道比較寬闊，流體的流動(dòng)不可能完全被葉片所夾持，使得長(zhǎng)葉片壓力面較厚邊界層內(nèi)的液體不能順利排出，因此在4葉片普通葉輪的流道中存在大面積的低速回流區(qū)，這種現(xiàn)象在8葉片復(fù)合葉輪中有所改善，而在12葉片葉輪中改善最為明顯。在12葉片葉輪中液流基本沿葉片的曲率流動(dòng)，可見(jiàn)分流葉片在一定程度上可以改善葉輪內(nèi)部的速度分布； (2)對(duì)數(shù)值模擬得到的3個(gè)葉輪內(nèi)部不同時(shí)刻的壓力場(chǎng)進(jìn)行了分析，發(fā)現(xiàn)12葉片葉輪內(nèi)部的靜壓分布較為均勻，靜壓曲線基本上沿圓周方向分布，且靜壓系數(shù)明顯大于4葉片葉輪相同半徑上葉片的靜壓系數(shù)。此外，蝸殼腔體以及出口的靜壓系數(shù)也較大，說(shuō)明分流葉片不僅可以改善泵內(nèi)部的壓力分布，同時(shí)也可以提高相同位置的壓力值； (3)對(duì)數(shù)值模擬得到蝸殼壁面附近的壓力脈動(dòng)進(jìn)行了分析，表明復(fù)合葉輪可以改善蝸殼內(nèi)部的壓力脈動(dòng)，值得注意的是，復(fù)合葉輪產(chǎn)生的壓力脈動(dòng)的頻率成分相比普通葉輪復(fù)雜，在復(fù)合葉輪中，除了基頻及其倍頻外，，長(zhǎng)葉片產(chǎn)生的頻率在低頻區(qū)上也會(huì)占主導(dǎo)地位； (4)針對(duì)3臺(tái)低比轉(zhuǎn)速離心泵進(jìn)行了外特性性能試驗(yàn)研究，試驗(yàn)結(jié)果表明，12葉片葉輪離心泵揚(yáng)程較高，但隨著葉片數(shù)的增大，軸功率會(huì)變大，在一定程度上會(huì)影響泵的效率。
[Abstract]:Centrifugal impeller is one of the main overflowing parts of low specific speed centrifugal pump. Its function is to transfer the mechanical energy of the prime mover directly to the fluid in order to improve the hydrostatic and dynamic pressure energy of the liquid. Therefore, the structure of impeller plays an important role in the flow field and performance of centrifugal pump. Based on the three-dimensional N-S equation and RNG k- 蔚 turbulence model, the impeller with four blades is studied in this paper. Three low specific speed centrifugal pumps with 8 vane and 12 vane composite impellers have been simulated by unsteady numerical simulation, and the external performance tests have been carried out. The main contents of the research are as follows: The whole flow field of the centrifugal pump with low specific speed of 4 vane 8 blade and 12 blade impeller was molded by PRO/E software. The internal flow is simulated with CFD software FLUENT, and the velocity field and pressure field of three centrifugal pumps at different times are analyzed. In addition, monitoring points were set up near the wall of the four sections of the volute and the part of the cochlea tongue, and the pressure pulsation near the wall of the volute was analyzed. Finally, the external performance of three low specific speed centrifugal pumps is predicted and tested numerically, and the numerical results are compared with the experimental results. After analysis, the following conclusions are obtained: 1) the velocity field of the three impellers at different times obtained by numerical simulation is analyzed. It is found that because there are no shunt blades arranged in the common impeller, the flow channels between adjacent long blades are relatively wide. The fluid flow can not be completely trapped by the blade, which makes the liquid in the thicker boundary layer of the long blade pressure surface can not be discharged smoothly. Therefore, there is a large area of low speed return zone in the passage of the 4 vane common impeller. This phenomenon has been improved in the compound impeller with 8 blades, but most obviously in the impeller with 12 blades. In the impeller with 12 blades, the liquid flow flows basically along the curvature of the blade. It can be seen that the shunt blade can improve the velocity distribution in the impeller to some extent. 2) the pressure field of three impellers at different times obtained by numerical simulation is analyzed. It is found that the static pressure distribution in 12 blade impellers is more uniform, and the hydrostatic pressure curve basically distributes along the circumferential direction. In addition, the static pressure coefficient of the volute cavity and outlet is larger, which indicates that the shunt blade can not only improve the pressure distribution inside the pump. At the same time, the pressure value of the same position can also be increased. 3) the pressure pulsation near the wall of the volute is analyzed by numerical simulation, which shows that the compound impeller can improve the pressure fluctuation inside the volute. The frequency component of pressure pulsation produced by composite impeller is more complex than that of common impeller. In compound impeller, the frequency produced by long blade also dominates in the low frequency region besides the fundamental frequency and frequency doubling. The external performance of three centrifugal pumps with low specific speed is studied. The experimental results show that the head of the centrifugal pump is higher, but with the increase of the number of blades, the shaft power will become larger. To some extent, it will affect the efficiency of the pump.
【學(xué)位授予單位】：浙江理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：TH311

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