叶片厚度变化规律对离心泵性能影响的研究

发布时间：2018-06-04 16:49

本文选题：离心泵 + 叶片厚度变化规律　；参考：《兰州理工大学》2011年硕士论文

【摘要】：水泵作为一种通用机械,将机械能转换为液体的动能和压力能,在国民经济中占有非常重要的地位。它的能耗占全国发电量20%左右,因此研究提高其性能具有重要的现实意义。叶轮是泵重要的过流和做功部件,其叶轮的轴面、叶片型线、叶片厚度变化规律对泵的性能影响较大。关于叶轮的轴面、叶片型线对离心泵性能的影响有学者做过相关研究,而关于叶片厚度变化规律对离心泵性能的影响方面的文献很少见到报道。因此,有必要研究叶片厚度变化规律对离心泵性能的影响。本文以三种不同比转速( n_s=49.9、97.8、187.9)的石油化工离心泵为基础,保证叶轮轴面尺寸不变,依据三种叶片厚度变化规律设计九种厚度翼型。对于( n_s=49.9)低比转速泵设计T1、T2、T3三种厚度翼型,得到三个离心泵方案:方案一、方案二、方案三;对于( n_s=97.8)中比转速泵设计T4、T5、T6三种厚度翼型,得到三个离心泵方案:方案四、方案五、方案六;对于( n_s=197.9)高比转速泵设计T7、T8、T9三种厚度翼型,得到三个离心泵方案:方案七、方案八、方案九。利用UGNX7.5建立离心泵的三维实体模型,运用FLUENT数值模拟软件进行数值计算,得到如下结论: 1.增大叶片(翼型)进口段厚度型线曲率半径可以达到减弱叶片表面二次流的目的,这与Johnson所分析的一致。 2.叶轮出口处尾流区的面积随流量的增大而减小,射流-尾迹流动结构随着流量的增大而减弱;叶轮出口处的尾流损失随叶片出口厚度的减小而减小,射流-尾迹流动结构随叶片出口厚度的减小而减弱。 3 .比转速不同叶轮出口处的尾流区分布和射流-尾迹损失也不相同。( n_s=49.9)低比转速离心泵尾流区主要分布在出口流道中部偏向压力面侧,在靠近压力面侧形成小范围的射流-尾迹流动结构;( n_s=97.8、187.9)中高比转速离心泵尾流区主要分布叶片吸力面和后盖板相交处,在整个流道出口形成大范围的射流-尾迹流动结构。 4.对于( n_s=49.9)低比转速离心泵,叶片厚度变化规律对泵扬程和效率影响较小,高效区随出口厚度的减薄向小流量点偏移;对于( n_s=97.8、187.9)中、高比转速离心泵,随着出口厚度的减薄扬程降低,效率提高。在小流量范围内叶片厚度变化规律对泵的扬程影响较大,在大流量范围内叶片厚度变化规律对泵的效率影响较大,高效区随出口厚度的减薄而变宽且向大流量点偏移。 5.叶片出口段厚度减薄且叶片出口到最大厚度距离为45~55mm时离心叶轮的整体性能较佳。采用上述厚度方案的方案二、五、七整体性能优于同一比转速下的其他方案。 6.对于( n_s=97.8)中比转速离心泵,方案四抗汽蚀性能最好,方案五次之,方案六抗汽蚀性能最差。叶片进口厚度型线越接近流线型泵的抗汽蚀性能越好,加大叶片进口段厚度型线曲率半径可以提高泵抗汽蚀性能。
[Abstract]:As a kind of universal machinery, water pump plays a very important role in the national economy by converting mechanical energy into kinetic energy and pressure energy of liquid. Its energy consumption accounts for about 20% of the country's electricity generation, so it has important practical significance to study and improve its performance. Impeller is an important part of pump flow and work. The axial plane, blade profile and blade thickness of impeller have great influence on the performance of pump. About the axial surface of impeller, the influence of blade profile on centrifugal pump performance has been studied by scholars, but there are few reports on the influence of blade thickness on centrifugal pump performance. Therefore, it is necessary to study the influence of blade thickness on the performance of centrifugal pump. In this paper, based on three kinds of centrifugal pumps with different specific rotational speeds (NSP, 49.9 ~ 97.8187.9), the axial dimensions of impeller are guaranteed to remain unchanged, and nine thickness airfoils are designed according to the variation of blade thickness of three kinds of impellers. For the design of three thickness airfoils of T _ 1 T _ 2T _ 3 and T _ 1 T _ 2T _ 3 for the low specific speed pump, three centrifugal pump schemes are obtained: scheme one, scheme two, scheme three, and for the three thickness airfoils designed by the specific speed pump in (nsl97.8), three kinds of thickness airfoils are obtained: scheme four, For the design of three thickness airfoils of T7 T8 and T9, three centrifugal pump schemes are obtained: scheme 7, scheme 8, scheme 9. The three-dimensional solid model of centrifugal pump is established by using UGNX7.5, and the numerical simulation software FLUENT is used to carry out the numerical calculation. The conclusion is as follows: 1. Increasing the thickness curve radius of the inlet section of the blade (airfoil) can weaken the secondary flow on the blade surface, which is consistent with the analysis by Johnson. 2. The wake area at the impeller outlet decreases with the increase of the flow rate, the jet wake flow structure weakens with the increase of the flow rate, and the wake loss at the impeller exit decreases with the decrease of the blade outlet thickness. The jet wake flow structure weakens with the decrease of blade outlet thickness. 3. The wake distribution and jet-wake loss at the outlet of different impellers are also different. (nssp / 49.9.) the wake area of low specific speed centrifugal pump is mainly distributed on the pressure side in the middle of outlet channel. A small range of jet wake flow structure is formed near the side of the pressure surface. A large range of jet wake flow structures are formed at the outlet of the whole channel at the intersection of the suction surface of the blade and the back cover plate in the wake area of the centrifugal pump with high specific speed. 4. For the low specific speed centrifugal pump, the blade thickness has little effect on the pump head and efficiency, and the high efficiency zone shifts to the small flow point along with the thickness of the outlet, and for the high specific speed centrifugal pump, it is found that in the (nssl997. 8187.9) centrifugal pump, the thickness of the impeller blade has little effect on the head and efficiency of the pump, and that of the high specific speed centrifugal pump is offset by the thickness of the outlet. With the decrease of the exit thickness, the efficiency is improved. In the range of small flow rate, the variation of blade thickness has a great influence on the lift of the pump. In the range of large flow rate, the variation law of blade thickness has a great influence on the efficiency of the pump. The high efficiency region becomes wider with the thickness of the outlet and shifts to the point of large flow. 5. The overall performance of centrifugal impeller is better when the thickness of the blade outlet section is thinned and the distance from the blade outlet to the maximum thickness is 45~55mm. The overall performance of two, five and seven schemes with the above thickness scheme is superior to other schemes with the same specific speed. 6. For the centrifugal pump with specific rotational speed, the fourth scheme has the best anti-cavitation performance, the fifth scheme has the best anti-cavitation performance, and the sixth scheme has the worst anti-cavitation performance. The closer the blade inlet thickness profile is to the better the anti-cavitation performance of the streamline pump, the greater the blade inlet thickness profile curvature radius can be, the better the cavitation resistance performance of the pump is.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH311

【相似文献】