CAJ | 학술논문

斜流泵具有高效，启动特性好，运行工况宽等特点。目前斜流泵设计时，无法定量评估叶顶间隙对性能影响的敏感性。为了揭示不同叶顶间隙值对斜流泵内部流场和性能的影响，给定叶顶间隙选取的范围。分别选取无叶顶间隙和叶顶间隙分别为0.5，1.0，1.5 mm共4种设计方案的斜流泵为对象，基于剪切压力传输模型（shear stress transport，SST k-ω）湍流模型，SIMPLEC算法与块结构化网格，对斜流泵内部流场进行数值模拟和试验验证。结果表明，叶顶间隙为0.5 mm时，可以有效抑制斜流泵的扬程-流量正斜率特性，此时斜流泵的效率值最高；无叶顶间隙时，斜流泵扬程-流量正斜率特性较为明显；叶顶间隙为1 mm时，数值模拟与试验结果吻合较好，SST k-ω模型可较好模拟斜流泵叶顶间隙区流动特征，性能预估结果具有一定的可信度。在小流量工况下，叶顶间隙为0.5 mm可有效抑制斜流泵的正斜率不稳定特性。小叶顶间隙0.5mm时，斜流泵水力性能最优；叶顶间隙增大时，叶顶泄漏流动逐渐显著，叶轮出口近壁区轴面流速和涡量分布规律显著变化，表明叶顶间隙直接影响叶轮轴面速度分布规律和叶片负荷分布规律，由于受壁面摩擦阻力和液体黏滞阻力的影响，叶轮轮毂和叶顶间隙侧的叶轮轴面速度较小；叶顶间隙增大时，叶轮轮毂和叶顶间隙侧叶片负荷急剧衰减，影响叶片的做功能力。同时，叶顶泄漏流动区域与叶片主流区域的掺混效应，使叶片轮缘的低速区扩展到叶轮流道内部的主流区域，引起叶轮流道内部主流流动的堵塞效应，产生二次流动、漩涡等流动不稳定现象。上述研究结果，揭示了叶顶间隙对斜流泵内部流场和性能的影响机理，为斜流泵叶顶间隙的选择提供了理论依据。
사류빙구유고효，계동특성호，운행공황관등특점。목전사류빙설계시，무법정량평고협정간극대성능영향적민감성。위료게시불동협정간극치대사류빙내부류장화성능적영향，급정협정간극선취적범위。분별선취무협정간극화협정간극분별위0.5，1.0，1.5 mm공4충설계방안적사류빙위대상，기우전절압력전수모형（shear stress transport，SST k-ω）단류모형，SIMPLEC산법여괴결구화망격，대사류빙내부류장진행수치모의화시험험증。결과표명，협정간극위0.5 mm시，가이유효억제사류빙적양정-류량정사솔특성，차시사류빙적효솔치최고；무협정간극시，사류빙양정-류량정사솔특성교위명현；협정간극위1 mm시，수치모의여시험결과문합교호，SST k-ω모형가교호모의사류빙협정간극구류동특정，성능예고결과구유일정적가신도。재소류량공황하，협정간극위0.5 mm가유효억제사류빙적정사솔불은정특성。소협정간극0.5mm시，사류빙수력성능최우；협정간극증대시，협정설루류동축점현저，협륜출구근벽구축면류속화와량분포규률현저변화，표명협정간극직접영향협륜축면속도분포규률화협편부하분포규률，유우수벽면마찰조력화액체점체조력적영향，협륜륜곡화협정간극측적협륜축면속도교소；협정간극증대시，협륜륜곡화협정간극측협편부하급극쇠감，영향협편적주공능력。동시，협정설루류동구역여협편주류구역적참혼효응，사협편륜연적저속구확전도협륜류도내부적주류구역，인기협륜류도내부주류류동적도새효응，산생이차류동、선와등류동불은정현상。상술연구결과，게시료협정간극대사류빙내부류장화성능적영향궤리，위사류빙협정간극적선택제공료이론의거。
The mixed-flow pump has some good characteristics, such as high efficiency, good start performance, and wide working condition. The traditional design methods of mixed-flow pumps cannot evaluate the sensitivity of the tip clearance’s impact on pump performance quantificationally. In order to reveal the tip clearance effect on the internal flow field and the performance of mixed-flow pump, and given the selection range of blade tip clearance, four mixed-flow pumps with different tip clearance values, 0, 0.5, 1.0, and 1.5 mm, respectively, were studied. The distorted triangle method was adopted to design the impeller and guide vane, and based on the software ICEM CFD to generate block hexahedron structured grids of the computational domain, and then the topological structure of the grids of the blade tip region was optimized. The internal flow field of the pumps was simulated based on the SST k-ωturbulence model and SIMPLEC algorithm, using the structured grid technology mentioned above, and the numerical simulation results were compared with the test experimental data, which agreed well with each other. The results show that the value of tip clearance have a significant effect on mixed-flow pump hydraulic performance, when tip clearance was 0.5 mm. The head-flow positive slope characteristic of the pump can be suppressed effectively, and the efficiency value of mixed-flow pump is highest at this time; when tip clearance was 0, the pump head-flow positive slope characteristic is relatively obvious;when tip clearance was 1mm, simulation values and experimental values matched well, so the SST k-ωmodel can simulate the flow characteristics of tip clearance of mixed-flow pumps well, so that the results of the performance prediction have some credibility. Under small flow conditions, small tip clearance values can restrain unstable positive slope features of mixed-flow pump. When tip clearance was 0.5mm, the performance of the pump with small tip clearance is the best. With the increasing of tip clearance value, tip leakage flow became outstanding gradually, the axis plane flow velocity of the near wall region of the impeller outlet and the vorticity change significantly, which indicates that tip clearance affects the axis plane velocity distributions of the impeller and the load distributions of the blades directly. As influenced by the frictional resistance and the viscous resistance of the wall, the impeller axis plane flow velocity of the impeller hub region and tip clearances areas is relatively small. When tip clearance increase, blades load of the impeller hub region and tip clearances areas decay rapidly, and it affects the performance ability of impeller blades. At the same time, serious mix permeability and entrainment effects come into being between the leakage flow near the blade tip and the main stream flow, and cause the significant decline in the axis plane flow velocity in the region near the blade tip of impeller outlet. At the moment, the jet effect of the tip leakage flow decays gradually, and the sphere of influence gradually extends to the entire blade tip region.