摘要
针对28CJ-70型立式轴流泵内部空化对机组性能的影响,从泵内空化基本方程出发,确立叶顶尖间隙γ、叶片吸力面流线分布和叶片进口边外缘修圆ψ为影响轴流泵空化特性的主要因素,并建立L9(33)正交实验表,分别对9组试验方案进行数值模拟,计算结果表明:叶顶尖间隙γ对叶轮吸力面外缘泄漏涡变化较为敏感,增大叶顶尖间隙γ能够有效改善吸力面外缘速度分布,但会使泵扬程降低;叶片吸力面流线分布Φ对轴流泵效率和空化持续长度χ具有重要影响,当吸力面流线分布Φ=0.7时,能够明显改善吸力面低压区流体回流范围,使空化持续长度χ迅速降低,并能大幅度减小空化体积分数.通过对立式轴流泵模型进行试验研究发现:数值模拟结果与试验外特性曲线能够较好符合,达到工程应用的要求,进而验证正交计算结果准确性.
Regarding the effects caused by the internal cavitation of 28CJ‐70 vertical axial‐flow pump on pump station performances ,based on the primary equation of inside‐pump cavitation ,the major factors w hich determined the net positive suction head of axial‐flow pump including the impeller top gaps (γ) ,the streamline distribution of impeller′s suction surface (φ) and the round of the impeller in‐let outer edge (ψ) were indicated ,and the orthogonal experiment L9 (33 ) was established to conduct numeric simulation for respectively 9 groups of experimental plans .The results show that the impeller top gaps (γ) is sensitive to the leakage vortex change of the outer edge of impeller suction surface ;w hen the gaps value increases ,the velocity distribution of outer edge of impeller suction surface dra‐matically improves ,thus the pumping head decreases .The streamline distribution of impeller′s suc‐tion surface possesses have vital influence on the efficiency and cavitation persistence length (χ) of ax‐ial‐flow pump .When the flow line of suction surfaceφ=0 .7 ,the backflow range in low‐pressure area can be obviously improved ,the cavitation persistence length can be rapidly decreased and the cavitati‐on volume fraction can be sharply cut .According to the analysis on model pump experiment ,it reveals that the numeric simulation results are well in line with the experimental external characteristic curves ,so that the correctness of orthogonal calculation results can be reasonably ensured and the re‐quirement of engineering application can be effectively met .
出处
《华中科技大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2014年第12期35-40,共6页
Journal of Huazhong University of Science and Technology(Natural Science Edition)
基金
国家自然科学基金资助项目(50879062)
湖北省水利厅重点科研项目(HBSLKJHT201307)
关键词
轴流泵
正交试验
空化
数值模拟
理论分析
模型泵试验
axial-flow pump
orthogonal experiment
cavitation
numerical simulation
theoretical analysis
model pump experiment
