摘要
基于RANS方程和SST k-ω湍流模型,对带前置导叶轴流泵进行三维非定常计算,研究了'马鞍区'工况进水流道回流涡的特性以及前置导叶对回流涡结构及压力脉动的影响,揭示了前置导叶提高轴流泵'马鞍区'工况扬程的机理。结果表明,小流量工况,轴流泵进水流道内形成大范围螺旋形回流,其与主流的剪切作用导致回流涡的产生,引起大量低频压力脉动,并造成能量损失,致使泵扬程下降,出现马鞍形;增设前置导叶可打破连续的回流涡,降低低频压力脉动幅值,提高轴流泵运行稳定性;同时,前置导叶可提高轴流泵扬程,消除扬程曲线马鞍形,且随着前置导叶位置不断靠近叶轮进口,泵扬程提高幅值不断增大;最后,前置导叶调角可进一步提高轴流泵扬程。
The hump characteristic is one of the detrimental characteristics of axial flow pump. If the pump runs in the hump region, some unsteady flows will occur, such as stall, backflow, cavitation and so on, which will reduce the pump performance. In order to analyze the hump characteristics, numerical method based on the RANS equations and SST k -ω turbulence model was used to simulate the instability flows in the axial flow pump with and without inlet guide vane. The hexahedral meshing scheme was used for the whole computational domain, particularly with O-grid around blades. The characteristics of swirling backflow vortex were firstly investigated. The influences of different distances between inlet guide vane and impeller blade on the swirling backflow vortices and the pressure fluctuations were studied. The effects of variable angles of inlet guide vane on pump performance were also discussed. The results showed that the predicted results were in good agreement with the experimental data. When the flow rate decreased, the backflow region was extended upstream. During the development of the backflow, the swirling vortices occurred in the shear layer between the swirling backflow and the main flow, which caused a lot of low frequency pressure fluctuations and consumed energies, leading to pump head decrease and hump characteristic. The swirling backflow vortices can be broken by inlet guide vane, resulting in decrease of amplitudes of low frequency pressure fluctuations and increase of pump head due to less energy consumed by the swirling vortices. Thus, the hump characteristic of axial flow pump can be improved by inlet guide vane. With the reduction of the distance between inlet guide vane and impeller blade, pump head was increased continuously. In addition, pump head was increased at negative angle of inlet guide vane, while it decreased at positive angle of inlet guide vane, which was resulted from the prewhirl regulation.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2016年第4期8-14,共7页
Transactions of the Chinese Society for Agricultural Machinery
基金
'十二五'国家科技支撑计划项目(2012BAD08B03)
关键词
轴流泵
回流涡
前置导叶
数值模拟
axial flow pump
backflow vortex
inlet guide vane
numerical simulation
