零二次流引射器启动性能数值研究

Numerical investigation on starting performance of zero-secondary flow ejectors

关键词:  引射器+  引射喷管  结构参数  启动性能+,压力恢复,数值仿真

Key words:  Ejector+  Shrouded nozzle  Structure parameter  Starting performance+  Pressure recovery  Numerical simulation

摘要:

为研究零二次流引射器结构参数如何影响其启动性能,采用数值方法模拟求解了引射器流场,并分析了引射器从启动到不启动的典型工作状态。结果表明:扩压器入口面积与引射喷管喉部面积之比Ad/At和第二喉道收缩比Ast/Ad是影响引射器性能的首要因素,其次是第二喉道长径比Lst/Dst和第二喉道入口的位置Ld/Dd。Ad/At越大,扩压器入口斜激波越强,总压损失越大,临界启动压比越大,越难以启动;Ast/Ad越小(大于其临界收缩比)则临界启动压比越小,越易于启动。

Abstract:

To investigate how the geometry parameters can influence starting performance in zero-secondary flow ejector,flow field of different ejectors were solved by CFD. The numerical simulation results were also applied to analyze ejector typical operation modes,ranging from on-design to off-design point. Results suggest that Ad/A t (area ratio of diffuser entrance to nozzle throat) and A st /A d (second-throat contraction ratio) are the most important parameters on the ejector performance,and L st /D st (ratio of length to diameter second-throat) and Ld/D d (second-throat location) also greatly influence the performance. The critical starting pressure ratio is increased by increasing Ad/At. When A st /Ad is higher than second-throat critical contraction ratio,its decrease benefits starting the ejector.