摘要
为了研究环状进气阀各阀片的不同步特性,对往复式压缩机的膨胀-进气过程进行计算流体动力学的数值模拟以确定进行阀完整的运动规律.在压缩机内流场的瞬态计算过程中,通过在每一时间步内调用编写的关于活塞和阀片运动方程、阀片撞击判断条件、撞击时的位移约束和反弹速度边界的C语言程序,计算出4个阀片在各时间步内的位移增量,同时,运用动网格技术对计算网格进行更新,实现了对不同阀片运动过程的动态模拟.在分析网格无关性的基础上,研究了弹簧刚度和曲轴转速对各阀片的运动以及气阀实际进气量的影响.计算结果表明:阀片的不同步运动主要表现为阀片自内环到外环的逐渐关闭,随着弹簧刚度的增大和转速的降低,不同步现象越来越明显,当转速为300 r/min时,第1个阀片发生颤振,而刚度从4 000 N/m增大至6 000 N/m时,第1,2个阀片先后出现颤振,进气量约为阀片整体运动时的0.8倍,计算时必须考虑不同步对进气量的影响.
In order to clarify motion characteristics of the ring inlet valve in a reciprocating compressor the expansion or suction process in the compressor was simulated with CFD approach by exploring the unsynchronizing motion of valve plates. During the unsteady flow simulations, a user defined C subroutine was composed to involve the motion functions of piston and four valve plates, displacement boundary conditions, impact criteria between valve plate and seat or lift limiter, displacement constrains for impact and rebound velocity boundary, eventually the displacement increments of four valve plates were determined at the end of each time step. Besides, the moving mesh technique was applied to update the mesh to realize a dynamic simulation of motion of various valve plates. Based on the mesh-independent feature identified, the effects of spring stiffness and crank shaft speed on the motion of the four valve plates and the flow rate through them were investigated. The simulated results show that theunsynchronizing motion of valve plates magnifies itself by showing different opening and closing angles from inner to outer of the plates. With inereasing spring stiffness and decreasing crankshaft speed, the unsynchronizing motion among four valve plates becomes more and more evident. Additionally, the inner or the first valve plate flutters initially at the speed of 300 r/min, however, when the spring stiffness is inereased to 6 000 N/m from 4 000 N/m, the second valve plate starts to flutter, and the flow rate is redueed to 0. 8 times the flow rate without unsynehronizing motion. This suggests that the unsynchronizing motion must be considered when a flow rate is under determination.
出处
《排灌机械工程学报》
EI
北大核心
2014年第5期422-428,共7页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家自然科学基金资助项目(60873021)
关键词
压缩机环状进气阀
不同步特性
数值分析
颤振
动网格
compressor ring inlet valve
not synchronous properties
numerical analysis
flutter
dynamic mesh
