叶顶喷气的喷嘴数目对轴流压气机稳定性影响的数值研究

Numerical Investigation of Injector Numbers on Stability of

关键词:  轴流压气机  叶顶喷气  喷嘴数目  数值模拟  稳定裕度  叶顶堵塞

Key words:  Axial flow compressor  Tip injection  Injector number  Numerical simulation  Stall margin  Tip blockage

摘要:

为了揭示叶顶喷气中喷嘴数目对跨声速压气机气动性能的影响，采用六通道非定常数值计算对一跨声速轴流压气机进行了数值研究。共选取两个喷气周向覆盖比例水平对喷嘴数量进行研究，主要分析喷嘴数目对压气机稳定裕度和流动参数径向分布的影响机理。研究表明喷嘴数目和喷气的周向覆盖比例都对压气机失速有影响，且这两参数间存在交互作用。当喷气的周向覆盖比例为54%时，喷嘴数目对压气机的稳定裕度没有影响；当叶顶喷气的周向覆盖比例为27%时，喷嘴数目由6个增加至18个，压气机流量裕度改进量由3.5%降低至2.5%。叶顶喷气对压气机稳定裕度提高在于喷气对叶顶堵塞的有效抑制，这种抑制作用需要单个喷嘴与叶顶反流区有充分的接触时间。喷嘴数目过多导致单个喷嘴与叶顶反流区的接触时间过短，无法有效降低叶顶堵塞。喷嘴的离散分布引起转子叶顶出口流动参数的非定常变化，其变化程度随喷嘴数目的增加而减小。对喷嘴数目的选择需综合考虑叶顶喷气对稳定裕度以及流动不均匀性的影响。

Abstract:

The effects of injector number on the aerodynamic performance of a transonic axial compressor with discrete tip injection were numerically studied using six-blade-passages three-dimensional unsteady simulations. The study on injector number was implemented at two levels of circumferential coverage percentage (CCP) of tip injection. This research focus on the mechanisms of injector number's influence on the stall margin and flow parameters' radial re-distributions. The results show that the interaction effect exits between the CCP and injector number，while they affect the stall range. When the CCP is 54%，the stall margin improvement is not affected by injector number. When the CCP is 27%，the stall margin improvement decreases from 3.5% to 2.5% as the injector number increases from 6 to 18. The effective depression on the tip blockage of tip injection，which should be guaranteed by a persistent interaction between the injected flow and tip reversed flow for each injector，is the main reason for the enhancement of compressor stability. The duration of the interaction for each injector is reduced by the increased number of injectors，leading to a less effective depression on the tip blockage. The discrete distributions of injectors make the flow at the outlet of the rotor tip region totally unsteady. The unsteady influence can be dampened by increasing the number of the injectors. To decide the best number，the effects of the tip injection on the stall margin and non-uniform flow should be considered.