摘要
为了对某汽轮机除湿级进行设计并优化,针对复杂湿蒸透平的除湿级,对单纯的汽相可压缩流动做了三维数值模拟,并进行详细的流场分析,研究了复杂三维除湿结构的单相气动性能.该除湿级在动叶片的吸力面上从50%叶高至叶冠开有7个除水沟槽,叶片顶部带有草帽型围带(即叶冠),围带内部中间开有疏水孔,叶冠上表面与通道端壁之间是有一定距离的间隙以利于除水.由于除湿级动叶的结构较为复杂,对其进行非结构化网格剖分,并对叶片前后缘、除水沟槽、疏水孔及叶顶间隙等特殊部位做了网格加密处理.针对叶轮机械的复杂内流,对除湿级的模拟采用了可实现k-ε湍流模型,在近壁面区域采用壁面函数法进行处理.在动静叶交界面,采用混合平面法来解决上下游交界面的强烈干扰.对除湿级进行的单相数值模拟结果揭示了在复杂的结构条件下级内的流场情况,能够使工程人员从气动特性上对沟槽、叶冠和间隙流动有所了解和认识,并为后续的两相流场计算奠定了基础.
To optimize the design of humidity-removing section of a wet steam turbine, a 3-D numerical simulation on pure compressible vapor-phase flow in this complex section was made. Detailed analysis on flow field was conducted. The single-phase aerodynamic performance of a complex 3-D humidity-removing structure was studied. In the section, there are seven humidity-removing radial-grooves machined on the suction-surface of the rotor from the mid point of the blade height to the rotor tip; at the blade tip, one straw-hat type cap with a draining orifice in the middle is covered; and there is a gap between upper surface of the cap and the end wall sufficient to permit removal of water collected from the rotor and end wall. Unstructured meshing was adopted due to the complexity of the rotor. In some special parts such as leading/ trailing edge of the blades, grooves, orifice and tip clearance, a refining division was performed to get a finer mesh. The realizable κ-ε model was applied to simulate complex inner flow in turbines and the wall function method was applied to model the near-wall region. To solve the intense interference of the rotor/ stator interface, the mixed plane model was applied. Numerical simulation of single-phase flow in the humidity-removing section showed flow details in the complex section which will give engineers a better understanding of flow in grooves, caps and clearances. The results of the single-phase flow-field study can also be the basis for subsequent two-phase flow simulations.
出处
《哈尔滨工程大学学报》
EI
CAS
CSCD
北大核心
2008年第8期803-808,共6页
Journal of Harbin Engineering University
关键词
除湿
湿蒸汽透平
单相
三维数值模拟
removing-humidity
wet steam turbine
single-phase
3-D numerical simulation
