Abstract: To explore the flow field structure during the dynamic process of single/double bypass model selection in variable cycle engine(VCE)，an experimental equipment designed by our group is used to imitate the dynamic process，and a two-dimensional numerical simulation by dynamic mesh is carried out on this experimental equipment. During the dynamic process，the mass flow’s and total pressure’s variations were found to lag behind the condition of valve’s switching at a low speed，and with the switching speed increased，the lag will become larger. However，the regulation of static pressure’s variation is contrary. Furthermore，we studied the effects of different initial bypass ratios on the lag during the closing process，and found that the smaller initial bypass ratio，the larger the lag will become，the lag reaches the maximum when the valve is closed to 22° on closing process.

Key words: Variable cycle engine；Model selection；Numerical simulation；Dynamic mesh

摘要： 为研究变循环发动机单/双涵道模式转换动态过程中流场参数的变化规律，基于本项目组设计的模拟模式转换过程的试验台，利用动网格技术对该试验台进行了二维数值模拟。结果表明:在模式转换动态过程中，内外涵流量和总压的变化滞后于阀门缓慢关闭的状态；并且阀门变化速率越快，其内涵总压和流量的动态响应越滞后；而静压的变化规律则相反。此外，还研究了在阀门关闭过程中，不同初始涵道比对这种流场参数变化滞后性的影响。发现初始涵道比越小，滞后性越强；并且这种滞后性在阀门关闭至22°位置时达到最大。

关键词: 变循环发动机；模式转换；数值计算；动网格技术