摘要
采用RNG k-ε湍流模型、完全空化模型对低扬程灯泡式贯流模型泵设计工况下的空化流动进行全流道数值计算,并预测其汽蚀性能曲线.选择包括空化开始出现、临界汽蚀余量点、空化严重时6个工况比较分析贯流泵内部空化流动的发展情况.计算获得了不同汽蚀余量时灯泡式贯流模型泵叶轮叶片吸力面静压、气体体积分数分布以及不同轴截面上的气体体积分数分布.计算结果表明:在给定的计算流量条件下,空化发生初期,空化发生在叶轮叶片吸力面的进口边,随着有效汽蚀余量的降低,预测了叶轮流道内的空化区域的演变,这些现象将会影响贯流泵的能量特性;在给定流量的其他空化条件下,当汽蚀余量为0.81 m时,Z=-20 mm横截面上的气体体积分数超过10%的区域占据了Z=-20 mm横截面进口流道的1/3,此时大量气泡严重堵塞叶轮流道.该灯泡式贯流泵空化流动的所有计算成果都可以被用来优化贯流泵的水力与结构设计.
Under the design operating condition, the RNG k -e turbulence model and the full cavita- tion model were employed to investigate cavitating flows in a bulb tubular pump model with low-head and predict its cavitation performance curve by using Fluent. The cavitating flow patterns in the pump un- der six operating conditions, where the cavitation inception, 3% head drop point and severe cavitation condition were included, were compared and analyzed. The static pressure and vapor volume fraction contours on the suction side of blade of the impeller and the fraction distributions in various planes lo- cated at different axial positions were obtained under different available NPSH. It was showed that a cavity occurs in the suction side of blade immediately behind the blade leading edge initially at a con- stant flow rate, and then it expands along the suction side with lowered available NPSH; such a cavity expansion affects the pump performance eventually. The one-third net cross-sectional area of flow pas- sages at the Z = - ：20 mm axial location has been occupied by the vapor with more than 10% volume fraction at the 0.81 m available NPSH, causing a serious blockage effect in the impeller passages. All the predicted results might be helpful in hydraulic and structural optimization for the bulb tubular pumpin future.
出处
《排灌机械工程学报》
EI
北大核心
2013年第3期185-189,199,共6页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家自然科学基金资助项目(50976124
51179192
51139007)
新世纪优秀人才支持计划项目(NETC-10-0784)
关键词
灯泡式贯流泵模型
湍流
湍流模型
汽蚀特性
空化模型
bulb tubular-pump model
turbulent flow
turbulent flow model
cavitation characteristics
cavitation model
