中国物理B ›› 2022, Vol. 31 ›› Issue (1): 14703-014703.doi: 10.1088/1674-1056/ac339b

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In situ measurement on nonuniform velocity distributionin external detonation exhaust flow by analysis ofspectrum features using TDLAS

Xiao-Long Huang(黄孝龙), Ning Li(李宁), Chun-Sheng Weng(翁春生), and Yang Kang(康杨)   

  1. National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China
  • 收稿日期:2021-07-15 修回日期:2021-10-02 接受日期:2021-10-27 出版日期:2021-12-03 发布日期:2021-12-28
  • 通讯作者: Ning Li E-mail:phoenixkyo@163.com
  • 基金资助:
    Project supported by the China Scholarship Council (Grant No. 201906845059), the Young Scientists Found of the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20190439), and the Fundamental Research Funds of National Key Laboratory of Transient Physics (Grant No. 6142604200202).

In situ measurement on nonuniform velocity distributionin external detonation exhaust flow by analysis ofspectrum features using TDLAS

Xiao-Long Huang(黄孝龙), Ning Li(李宁), Chun-Sheng Weng(翁春生), and Yang Kang(康杨)   

  1. National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China
  • Received:2021-07-15 Revised:2021-10-02 Accepted:2021-10-27 Online:2021-12-03 Published:2021-12-28
  • Contact: Ning Li E-mail:phoenixkyo@163.com
  • Supported by:
    Project supported by the China Scholarship Council (Grant No. 201906845059), the Young Scientists Found of the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20190439), and the Fundamental Research Funds of National Key Laboratory of Transient Physics (Grant No. 6142604200202).

摘要: Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution. This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution, to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity. Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform. With simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model, this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10-3. This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz, and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry. This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations, which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.

关键词: velocity distribution, tunable diode laser absorption spectroscopy, nonuniform flow, Doppler effect

Abstract: Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution. This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution, to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity. Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform. With simulated optical measurement using H2O feature at 7185.6 cm-1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model, this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2×10-3. This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz, and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry. This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations, which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.

Key words: velocity distribution, tunable diode laser absorption spectroscopy, nonuniform flow, Doppler effect

中图分类号:  (Detonation waves)

  • 47.40.Rs
78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)) 52.70.Kz (Optical (ultraviolet, visible, infrared) measurements)