摘要
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。
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-ω turbulence 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-ω model 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,
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2014年第23期86-93,F0003,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家科技支撑计划(2013BAF01B02)
国家自然科学基金资助项目(51369015)
甘肃省自然科学基金资助项目(2011GS04264)
关键词
泵
数值分析
流场
斜流泵
叶顶间隙
泄漏流动
外特性
pumps
numerical analysis
flow fields
mixed-flow pump
tip clearance
leakage flow
external characteristic
