可逆式对旋轴流泵的模型设计与数值分析

发布时间：2018-05-26 17:51

本文选题：可逆 + 对旋　；参考：《华中科技大学》2014年硕士论文

【摘要】：与传统单级轴流泵相比，对旋轴流泵是将传统轴流泵的后置静叶用后置动叶代替，前后置叶轮反向旋转而得到的轴流泵。后置叶轮不仅可以回收前置叶轮出口的动能，同时给液流二次加功，因而对旋轴流泵具有体积小、扬程高、空化性能好等特点。本文以高效可逆式对旋轴流泵为研制目标，结合模型设计、定常及非定常数值模拟方法，探讨对旋轴流泵应用于双向运行场合的可行性。模型设计采用轴流泵线性环量修正和流线法相结合，以分析叶轮进出口的速度三角形为研究基础，提出可逆式对旋轴流泵叶轮的设计思路，并应用MATLAB7.0对设计过程进行参数化。基于FLUENT软件，就可逆式对旋轴流泵后置叶轮进口绝对速度的圆周分量、级间的负荷分配方案进行分析；为提高可逆对旋轴流泵反向运行的性能，通过对NACA0009翼型进行修正，得到椭圆型的双对称翼型NACA0009-ellipse，并给出这种翼型在有拱度和无拱度下的性能对比分析结果；为研究两级叶轮间的匹配问题，初步分析了轴向间隙、径向间隙对可逆式对旋轴流泵的影响。结果表明：联合假设条件下，泵内流态较好，但泵的有效工作范围变窄；级间负荷分配对泵总体特性影响较小，增大负荷比可以改善后置叶轮反向运行时的空化性能；反向运行时，叶轮按无拱度条件下的双对称翼型进行加厚，可以有效减小叶片吸力面的回流损失，提高泵反向运行性能；轴向间隙取后置叶轮叶中弦长的80%获得的水力性能相对较好；前后置叶轮叶顶泄漏涡的成因与传播特性基本相似，都是在翼型头部正背面大压力差的作用下形成，在叶片卷吸作用下，往叶片旋转的反方向移动，涡的强度随之减弱，另外，后置叶轮的叶顶泄漏涡受前置叶轮的影响有往主流方向移动的趋势。结合时间推进法及滑移网格技术，，在定常计算的基础上完成可逆式对旋轴流泵全流道三维非定常计算及动态性能预测，给出设计流量工况及小流量工况下的内流场，并对级间瞬态干涉进行分析。结果表明：动/动干涉面及对旋基元级上的涡量和压力分布具有明显的周期性，可直观地反映动/动叶栅的干涉过程。
[Abstract]:Compared with the traditional single-stage axial flow pump, the counter-rotating axial flow pump is an axial flow pump, which is obtained by replacing the rear static vane of the traditional axial flow pump with the rear moving vane and rotating the front and front impeller in reverse direction. The rear impeller can not only recover the kinetic energy from the outlet of the front impeller, but also add secondary power to the liquid flow, so the counterrotating axial flow pump has the characteristics of small volume, high lift and good cavitation performance. In this paper, the feasibility of applying counterrotating axial flow pump to bidirectional operation is discussed with the aim of developing high efficiency reversible counter-rotating axial flow pump, combined with model design, steady and unsteady numerical simulation method. The design of the model is based on the linear loop correction of axial flow pump and the streamline method. Based on the analysis of the velocity triangle of impeller inlet and outlet, the design idea of reversible counterrotating axial flow pump impeller is put forward, and the design process is parameterized by MATLAB7.0. Based on FLUENT software, this paper analyzes the circumferential component of the absolute velocity at the inlet of the rear impeller of a reversible counter-rotating axial flow pump and the load distribution scheme between stages. In order to improve the reverse operation performance of the reversible counter-rotating axial flow pump, the airfoil of NACA0009 is modified. The elliptical double symmetric airfoil NACA0009-ellipse is obtained, and the results of comparative analysis of the performance of this airfoil under the condition of arch and no arch are given. In order to study the matching problem between two stage impellers, the axial clearance is preliminarily analyzed. Effect of radial clearance on reversible counterrotating axial flow pump. The results show that the internal flow state of the pump is better, but the effective working range of the pump becomes narrower under the combined assumption, and the effect of inter-stage load distribution on the overall performance of the pump is small, and the cavitation performance of the rear impeller can be improved by increasing the load ratio. When the impeller is thickened under the condition of no arch, the backflow loss of the suction surface of the blade can be reduced effectively, and the reverse operation performance of the pump can be improved. The hydraulic performance obtained by taking 80% of the chord length in the blade of the rear impeller with axial clearance is relatively good, and the cause of the leakage vortex at the top of the front and rear impeller is basically similar to the propagation characteristic, which is formed under the action of the large pressure difference on the back of the head of the airfoil. Under the action of blade entrainment, the vortex intensity decreases as the blade rotates in the opposite direction. In addition, the tip leakage vortex of the rear impeller tends to move to the mainstream direction under the influence of the front impeller. Combined with time advance method and sliding grid technology, the three-dimensional unsteady calculation and dynamic performance prediction of the full channel of reversible counter-rotating axial flow pump are completed on the basis of steady calculation, and the internal flow field under the condition of design flow and small flow rate is given. The interstage transient interference is analyzed. The results show that the vorticity and pressure distribution on the dynamic / dynamic interference surface and the counterrotating element level are obviously periodic, which can directly reflect the interference process of the moving / moving cascade.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TH312

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