Eckardt离心叶轮失速流场非定常特征分析
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摘要
为明确离心压气机失速流场特征及类型,对Eckardt离心叶轮进行全通道非定常流场模拟,得到以下失速流场特征结果:(1)叶片前缘叶顶区域明显存在4个突尖型失速团,同时前缘涡、通道涡和低速二次涡共同作用形成流道内的非定常不稳定流动,诱发旋转失速;(2)与轴流叶轮突尖失速特征相似,离心叶轮内同样存在前缘溢流,但不存在尾缘反流,而呈现与径向和周向扭曲结构相关的新特征:叶顶间隙流与流道中的偏转二次流汇合,形成尺度更小、范围更大的低速二次涡。经进一步的空间傅里叶分析,确定失速团以60%～73%的叶轮转速沿周向传播,且由叶轮入口向下游移动,伴随发生涡脱落和破碎,使流场进入深度失速状态。通过分析这些失速流场特征,得出离心叶轮中突尖失速特征与轴流相比既有相同之处也有不同之处的结论。
To investigate the characteristics and the types of rotating stall in centrifugal compressor, the full-annual unsteady numerical simulation with software CFX was carried out on Eckardt impeller. Results show:(1) There exist four spike-type stall cells on the blade leading edge near shroud endwall. The unsteady and unstable flow in the channel is formed by the interaction of the leading edge vortex, the channel vortex and the low-velocity secondary vortex, which induces the rotational stall.(2) Similar to the spike-type stall in axial flow impeller, leading edge spillage also occurs in centrifugal impeller channel. Meanwhile, due to the strong meridian and circumferential twist, the trailing edge backflow shows new characteristics for centrifugal impeller: the confluence of the tip leakage flow and secondary flow lead to multiple smaller-scale secondary vortices in a larger area. A further spatial fast Fourier transform analysis indicates that the spike stall cells move at about 60%-73% of the rotor speed along circumference, and go deep into the downstream of channel with shedding and breakdown of vortices, which makes the flow field deteriorate into deep stall status. Based on the analysis for characteristics of rotating stall, it can be concluded that the characteristics of rotating stall for the leading edge of centrifugal compressor not only show similar aspects but also some different aspects, compared with axial compressor.
To investigate the characteristics and the types of rotating stall in centrifugal compressor, the full-annual unsteady numerical simulation with software CFX was carried out on Eckardt impeller. Results show:(1) There exist four spike-type stall cells on the blade leading edge near shroud endwall. The unsteady and unstable flow in the channel is formed by the interaction of the leading edge vortex, the channel vortex and the low-velocity secondary vortex, which induces the rotational stall.(2) Similar to the spike-type stall in axial flow impeller, leading edge spillage also occurs in centrifugal impeller channel. Meanwhile, due to the strong meridian and circumferential twist, the trailing edge backflow shows new characteristics for centrifugal impeller: the confluence of the tip leakage flow and secondary flow lead to multiple smaller-scale secondary vortices in a larger area. A further spatial fast Fourier transform analysis indicates that the spike stall cells move at about 60%-73% of the rotor speed along circumference, and go deep into the downstream of channel with shedding and breakdown of vortices, which makes the flow field deteriorate into deep stall status. Based on the analysis for characteristics of rotating stall, it can be concluded that the characteristics of rotating stall for the leading edge of centrifugal compressor not only show similar aspects but also some different aspects, compared with axial compressor.
引文
[1]Moore F K,Greitzer E M.A Theory of Post-Stall Transients in Axial Compression Systems:Part I-Development of the Equations[J].Journal of Engineering for Gas Turbines and Power,1986,108(1):68-76.
[2]Camp T R,Day I J.A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor[J].Journal of Turbomachinery,1998,120(3):393-401.
[3]Vo H D,Tan C S,Greitzer E M.Criteria for Spike Initiated Rotating Stall[J].Journal of Turbomachinery,2008,130(1):155-165.
[4]Chen J P,Hathaway M D,Herrick G P.Prestall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation[J].Journal of Turbomachinery,2008,130(4):353-368.
[5]吴艳辉,安光耀,陈智洋,等.跨声速压气机转子近失速工况非定常流动及相关机理研究[J].推进技术,2016,37(10):1847-1854.(WU Yan-hui,ANGuang-yao,CHEN Zhi-yang,et al.Numerical Investigation into Unsteady Flow and Its Associated Flow Mechanism in a Transonic Compressor Rotor at near Stall Conditions[J].Journal of Propulsion Technology,2016,37(10):1847-1854.)
[6]吴艳辉,王晓,稂仿玉,等.单级轴流压气机失速起始的数值模拟[J].航空动力学报,2014,29(1):125-132.
[7]Spakovszky Z S,Roduner C H.Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor[J].Journal of Turbomachinery,2009,131(3):1745-1755.
[8]Everitt J N,Spakovszky Z S.An Investigation of Stall Inception in Centrifugal Compressor Vaned Diffuser[J].Journal of Turbomachinery,2013,135(1):1737-1749.
[9]杨策,王营军,佟鼎,等.带有蜗壳的离心压气机进口失速先兆位置的确定及其成因分析[J].推进技术,2017,38(4):787-796.(YANG Ce,WANGYing-jun,TONG Ding,et al.Certainty and Interpretation of Inlet Stall Inception Position Caused by Volute Tongue in a Centrifugal Compressor[J].Journal of Propulsion Technology,2017,38(4):787-796.)
[10]Ludtke K H.Process Centrifugal Compressors[M].Berlin:Springer,2010.
[11]Eckardt D.Instantaneous Measurements in the JetWake Discharge Flow of a Centrifugal Compressor Impeller[J].Journal of Engineering for Gas Turbines and Power,1975,97(3):337-345.
[12]孙志刚,何平,李文,等.Eckardt叶轮数值计算与实验对比[J].工程热物理学报,2011,32(5):767-770.
[13]Barth T J,Jesperson D C.The Design and Application of Upwind Schemes on Unstructured Meshes[R].AIAA89-0366.
[14]Eckardt D.Detailed Flow Investigations Within a High Speed Centrifugal Compressor Impeller[J].Journal of Engineering for Gas Turbines and Power,1976,98(3):390-399.
[15]孙志刚,胡良军,何平,等.Eckardt叶轮二次流与射流尾迹结构研究[J].工程热物理学报,2011,32(12):2017-2021.
[16]芮国胜,康健.小波与傅里叶分析基础[M].北京:电子工业出版社,2010.
[17]张磊,王松岭,胡晨星.叶轮机械旋转失速研究进展[J].热力发电,2014,(1):1-5.
[18]李清鹏,吴艳辉,楚武利,等.轴流压气机转子近失速工况全通道数值模拟[J].航空动力学报,2011,26(10):2330-2338.
[19]Day I J.Stall Inception in Axial Flow Compressors[R].ASME 91-GT-086.
[20]鲁业明,刘正先.离心叶轮叶顶间隙泄漏流影响因素的量化分析研究[J].推进技术,2017,38(1):76-84.(LU Ye-ming,LIU Zheng-xian.Quantitative Analysis of Influence Factors on Leakage Flow of Tip Clearance in Centrifugal Impellers[J].Journal of Propulsion Technology,2017,38(1):76-84.)
[21]Hitich C,Kang S,Pointel G.A Numerically Supported Investigation of the 3D Flow in Centrifugal Impellers:Part II-Secondary Flow Structure[R].ASME 96-GT-152.
[2]Camp T R,Day I J.A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor[J].Journal of Turbomachinery,1998,120(3):393-401.
[3]Vo H D,Tan C S,Greitzer E M.Criteria for Spike Initiated Rotating Stall[J].Journal of Turbomachinery,2008,130(1):155-165.
[4]Chen J P,Hathaway M D,Herrick G P.Prestall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation[J].Journal of Turbomachinery,2008,130(4):353-368.
[5]吴艳辉,安光耀,陈智洋,等.跨声速压气机转子近失速工况非定常流动及相关机理研究[J].推进技术,2016,37(10):1847-1854.(WU Yan-hui,ANGuang-yao,CHEN Zhi-yang,et al.Numerical Investigation into Unsteady Flow and Its Associated Flow Mechanism in a Transonic Compressor Rotor at near Stall Conditions[J].Journal of Propulsion Technology,2016,37(10):1847-1854.)
[6]吴艳辉,王晓,稂仿玉,等.单级轴流压气机失速起始的数值模拟[J].航空动力学报,2014,29(1):125-132.
[7]Spakovszky Z S,Roduner C H.Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor[J].Journal of Turbomachinery,2009,131(3):1745-1755.
[8]Everitt J N,Spakovszky Z S.An Investigation of Stall Inception in Centrifugal Compressor Vaned Diffuser[J].Journal of Turbomachinery,2013,135(1):1737-1749.
[9]杨策,王营军,佟鼎,等.带有蜗壳的离心压气机进口失速先兆位置的确定及其成因分析[J].推进技术,2017,38(4):787-796.(YANG Ce,WANGYing-jun,TONG Ding,et al.Certainty and Interpretation of Inlet Stall Inception Position Caused by Volute Tongue in a Centrifugal Compressor[J].Journal of Propulsion Technology,2017,38(4):787-796.)
[10]Ludtke K H.Process Centrifugal Compressors[M].Berlin:Springer,2010.
[11]Eckardt D.Instantaneous Measurements in the JetWake Discharge Flow of a Centrifugal Compressor Impeller[J].Journal of Engineering for Gas Turbines and Power,1975,97(3):337-345.
[12]孙志刚,何平,李文,等.Eckardt叶轮数值计算与实验对比[J].工程热物理学报,2011,32(5):767-770.
[13]Barth T J,Jesperson D C.The Design and Application of Upwind Schemes on Unstructured Meshes[R].AIAA89-0366.
[14]Eckardt D.Detailed Flow Investigations Within a High Speed Centrifugal Compressor Impeller[J].Journal of Engineering for Gas Turbines and Power,1976,98(3):390-399.
[15]孙志刚,胡良军,何平,等.Eckardt叶轮二次流与射流尾迹结构研究[J].工程热物理学报,2011,32(12):2017-2021.
[16]芮国胜,康健.小波与傅里叶分析基础[M].北京:电子工业出版社,2010.
[17]张磊,王松岭,胡晨星.叶轮机械旋转失速研究进展[J].热力发电,2014,(1):1-5.
[18]李清鹏,吴艳辉,楚武利,等.轴流压气机转子近失速工况全通道数值模拟[J].航空动力学报,2011,26(10):2330-2338.
[19]Day I J.Stall Inception in Axial Flow Compressors[R].ASME 91-GT-086.
[20]鲁业明,刘正先.离心叶轮叶顶间隙泄漏流影响因素的量化分析研究[J].推进技术,2017,38(1):76-84.(LU Ye-ming,LIU Zheng-xian.Quantitative Analysis of Influence Factors on Leakage Flow of Tip Clearance in Centrifugal Impellers[J].Journal of Propulsion Technology,2017,38(1):76-84.)
[21]Hitich C,Kang S,Pointel G.A Numerically Supported Investigation of the 3D Flow in Centrifugal Impellers:Part II-Secondary Flow Structure[R].ASME 96-GT-152.