Abstract:

There is no reason in the design of orifice plate for condensation regulating pipeline,which could lead to cavitation downstream the orifice plate and brush pipeline with high fluid velocity.Severe vibration and brush corrosion were induced.Consequently,these affected the safety and stability of condensation pipeline extremely.Based on the mechanism of porous muffler with noise reduction,a new inclined hole hedge throttle orifice with the function of preventing cavitation and slow brush was proposed.The Bernoulli equation and block pressure difference method were introduced.Its aperture,and the thickness of the series were calculated and then two-stage inclined hole throttle orifice was obtained.The designed single-stage and two-stage throttle orifice were analyzed by means of numerical simulation.The calculated results show that the large scale vortex and the cavitation phenomenon would occur downstream single-stage throttle orifice,which caused the vibration for condensation pipeline easily.Two-stage throttle orifice not only could avoid cavitation from throttle orifice but also bring about fluid hedge jet effect.This may counteract jet energy from different inclined holes each other and slow fluid brush.The results of numerical simulation were basically consistent with theoretical design data. Therefore,the calculation method could provide theoretical support for the structural design of throttle orifice applying to marine condensation pipeline.

Key words: new throttle orifice, cavitation, numerical simulation

摘要：

船用凝水管道上节流孔板设计不合理,易导致孔板下游流体发生汽蚀,并促使流体高速冲击管道,进而诱发管道剧烈振动和冲刷腐蚀失效,极大影响了船用凝水管道的安全性和稳定性。基于多孔消声器减振降噪机理,提出了具有"防止孔板汽蚀,减缓管路冲刷"功能的新型斜孔对冲式节流孔板,引入伯努利方程和阻塞压差计算方法,进行节流孔板孔径、级数和厚度的校核计算,得到适用于凝水调节管道的两级斜孔式节流孔板,并利用数值模拟手段对理论设计的单级和二级斜孔式孔板节流特性进行分析,计算结果表明单级节流孔板下游局部流域诱发大尺度涡流和汽蚀现象,易导致凝水管路振动;二级节流孔板不仅可以规避孔板诱发汽蚀,还能实现流体对冲射流效应,促使冲击能量相互抵消,减缓流体对管路的冲刷,数值模拟结果与理论设计数据基本吻合。因此该计算方法可为船舶凝水系统管道节流孔板结构设计提供一定理论支撑。

关键词: 新型节流件, 汽蚀, 数值模拟