燃烧流场羟基示踪测速的噪声去除方法
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摘要
为了保证燃烧流场羟基(OH)示踪速度测量的精度,开展了背景噪声去除方法研究。基于燃烧流场羟基示踪测速数据的噪声特性分析,构建了染噪的数值模型;针对局部的燃烧OH荧光干扰以及流场杂散光等背景噪声,采用了基于Hough变换的空间滤波方法。针对测量系统的物理、电、光以及传感器等噪声,采用了小波变换的噪声去除方法,提高了图像信噪比。提出了一种将两种方法融合的背景去除方法,抑制了系统噪声对空间滤波算法精度的影响,优化了空间滤波结果。研究结果表明,图像处理后峰值信噪比提高了16.79 dB,信噪比提高了13.91 dB。对燃烧流场实验数据进行了处理,有效地抑制了背景噪声,达到了图像预处理的效果,满足了激光诊断系统对测量精度的要求。
In order to guarantee the precision of hydroxyl(OH) tagging velocimetry measurement in combustion flow field, we investigate a background noise removal method. Based on the analysis of noise characteristics of hydroxyl tagging velocimetry experimental data in combustion flow fields, we construct a numerical model of noise attenuation. For the background noise such as local combustion OH fluorescence interference and flow stray light, we adopt a spatial filtering method based on Hough transform. As for the physical, electrical, optical and sensor noises of the measurement system, we present a noise removal method of wavelet transform to improve signal-to-noise ratio. The background noise suppression method combining spatial filtering and wavelet transform is proposed to suppress system noise effect on the spatial filtering algorithm precision, and optimize the spatial filtering results. The research results show that the peak signal-to-noise ratio is improved by 16.79 dB, and signal-to-noise ratio is improved by 13.91 dB after imaging processing. The experimental data of combustion flow field are processed, which effectively suppresses background noise, achieves the effect of image preprocessing, and meets the requirement of measurement accuracy of laser diagnostic system for measurement accuracy.
In order to guarantee the precision of hydroxyl(OH) tagging velocimetry measurement in combustion flow field, we investigate a background noise removal method. Based on the analysis of noise characteristics of hydroxyl tagging velocimetry experimental data in combustion flow fields, we construct a numerical model of noise attenuation. For the background noise such as local combustion OH fluorescence interference and flow stray light, we adopt a spatial filtering method based on Hough transform. As for the physical, electrical, optical and sensor noises of the measurement system, we present a noise removal method of wavelet transform to improve signal-to-noise ratio. The background noise suppression method combining spatial filtering and wavelet transform is proposed to suppress system noise effect on the spatial filtering algorithm precision, and optimize the spatial filtering results. The research results show that the peak signal-to-noise ratio is improved by 16.79 dB, and signal-to-noise ratio is improved by 13.91 dB after imaging processing. The experimental data of combustion flow field are processed, which effectively suppresses background noise, achieves the effect of image preprocessing, and meets the requirement of measurement accuracy of laser diagnostic system for measurement accuracy.
引文
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[2] Dam N, Klein-Douwel R J H, Sijtsema N M, et al. Nitric oxide flow tagging in unseeded air[J]. Optics Letters, 2001, 26(1): 36-38.
[3] Michael J B, Edwards M R, Dogariu A, et al. Femtosecond laser electronic excitation tagging for quantitative velocity imaging in air[J]. Applied Optics, 2011, 50(26): 5158-5162.
[4] Ribarov L A, Wehrmeyer J A, Hu S, et al. Multiline hydroxyl tagging velocimetry measurements in reacting and nonreacting experimental flows[J]. Experiments in Fluids, 2004, 37(1): 65-74.
[5] Pan F, Sánchez-González R, McIlvoy M H, et al. Simultaneous three-dimensional velocimetry and thermometry in gaseous flows using the stereoscopic vibrationally excited nitric oxide monitoring technique[J]. Optics Letters, 2016, 41(7): 1376-1379.
[6] Si Hadj Mohand H, Frezzotti A, Brandner J J, et al. Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion[J]. Experimental Thermal and Fluid Science, 2017, 83: 177-190.
[7] Chen F, Liu H, Li H X, et al. An experimental investigation with molecular tagging technique on the spray flow ejected from an air-blast nozzle[C]//AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Washington, D.C. Reston, VA: AIAA, 2015: 2016-3251.
[8] Zhang Z R, Zhu F, Li G H, et al. Research on spontaneous Raman scattering excited by XeF(C-A) laser[J]. Acta Optica Sinica, 2014, 34(11): 1114001. 张振荣, 朱峰, 李国华, 等. 基于XeF (C-A)激光激励的自发拉曼散射技术研究[J]. 光学学报, 2014, 34(11): 1114001.
[9] Zhang L R, Hu Z Y, Ye J F, et al. Mobile CARS temperature measurements at exhaust of supersonic combustor[J]. Chinese Journal of Lasers, 2013, 40(4): 0408007. 张立荣, 胡志云, 叶景峰, 等. 移动式CARS系统测量超声速燃烧室出口温度[J]. 中国激光, 2013, 40(4): 0408007.
[10] Wang S, Shao J, Li G H, et al. Multi-point velocity measurement of gas flow field based on detecting the Doppler frequency shift of molecular rayleigh scattering[J]. Chinese Journal of Lasers, 2015, 42(10): 1015002. 王晟, 邵珺, 李国华, 等. 基于检测分子瑞利散射光多普勒频移的流场多点速度测量[J]. 中国激光, 2015, 42(10): 1015002.
[11] Tao B, Ye J F, Zhao X Y, et al. Temperature measurement of instantaneous supersonic flow based on absorption spectroscopy technology[J]. Chinese Journal of Lasers, 2011, 38(12): 1215002. 陶波, 叶景峰, 赵新艳, 等. 基于激光吸收光谱技术测量瞬态超声速流场温度[J]. 中国激光, 2011, 38(12): 1215002.
[12] Zhang S H, Yu X L, Yan H, et al. Molecular tagging velocimetry of NH fluorescence in a high-enthalpy rarefied gas flow[J]. Applied Physics B, 2017, 123(4): 122.
[13] Raffel M, Willert C E, Wereley S T, et al. Particle image velocimetry. A practical guide[M]. Berlin, Heidelberg: Springer-Verlag, 2007.
[14] Ribarov L A, Wehrmeyer J A, Pitz R W, et al. Hydroxyl tagging velocimetry (HTV) in experimental air flows[J]. Applied Physics B: Lasers and Optics, 2002, 74(2): 175-183.
[15] André M A, Bardet P M, Burns R A, et al. Development of hydroxyl tagging velocimetry for low velocity flows[C]//AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Washington, D.C. Reston, VA: AIAA, 2015: 2016-3247.
[16] Pitz R W, Lahr M D, Douglas Z W, et al. Hydroxyl tagging velocimetry in a supersonic flow over a cavity[J]. Applied Optics, 2005, 44(31): 6692-6700.
[17] Lahr M D, Pitz R W, Douglas Z W, et al. Hydroxyl-tagging-velocimetry measurements of a supersonic flow over a cavity[J]. Journal of Propulsion and Power, 2010, 26(4): 790-797.
[18] Perkins A N, Ramsey M, Strickland D J, et al. Dual-pulse hydroxyl tagging velocimetry (HTV) in jet engine exhausts[C]// AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Denver, Colorado. Reston, VA: AIAA, 2009: 2009-5108.
[19] Zhang Z R, Li G H, Ye J F, et al. On-line measurement of species concentration in flow field of scramjet engine[J]. Optics and Precision Engineering, 2016, 24(4): 709-713. 张振荣, 李国华, 叶景峰, 等. 超燃发动机流场组分浓度的在线测量[J]. 光学精密工程, 2016, 24(4): 709-713.
[20] Li G H, Hu Z Y, Wang S, et al. 2D scanning CARS for temperature distribution measurement[J]. Optics and Precision Engineering, 2016, 24(1): 14-19. 李国华, 胡志云, 王晟, 等. 基于相干反斯托克斯拉曼散射的二维温度场扫描测量[J]. 光学精密工程, 2016, 24(1): 14-19.
[21] Ye J F, Hu Z Y, Liu J R, et al. Development and application of molecular tagging velocimetry[J]. Journal of Experiments in Fluid Mechanics, 2015, 29(3): 11-17, 61. 叶景峰, 胡志云, 刘晶儒, 等. 分子标记速度测量技术及应用研究进展[J]. 实验流体力学, 2015, 29(3): 11-17,61.
[22] Ye J F, Shao J, Li G H, et al. Vibration disturbance suppression in velocity measurements by hydroxyl tagging velocimetry[J]. Optics and Precision Engineering, 2017, 25(7): 1689-1696. 叶景峰, 邵珺, 李国华, 等. 羟基分子标记示踪速度测量中的强振动干扰抑制[J]. 光学精密工程, 2017, 25(7): 1689-1696.
[23] Gendrich C P, Koochesfahani M M. A spatial correlation technique for estimating velocity fields using molecular tagging velocimetry (MTV)[J]. Experiments in Fluids, 1996, 22(1): 67-77.
[24] Ramsey M C, Pitz R W. Template matching for improved accuracy in molecular tagging velocimetry[J]. Experiments in Fluids, 2011, 51(3): 811-819.
[25] van de Water W, Dam N. How to find patterns written in turbulent air[J]. Experiments in Fluids, 2013, 54(9): 1574-1583.
[26] Sanchez-Gonzalez R, McManamen B, Bowersox R D W, et al. A method to analyze molecular tagging velocimetry data using the Hough transform[J]. Review of Scientific Instruments, 2015, 86(10): 105106.
[27] Shao J, Ye J F, Hu Z Y, et al. Progressive approach characteristic window filtering for HTV background suppression in supersonic combustion field[J]. Optics and Precision Engineering, 2015, 23(10): 221-228. 邵珺, 叶景峰, 胡志云, 等. 用于超燃流场羟节标记示踪背景抑制的逐步逼近特征窗口滤波[J]. 光学精密工程, 2015, 23(10): 221-228.
[28] Shao J, Ye J F, Li J Y. A background removal approach to the study of hydroxyl tagging velocimetry in supersonic combustion flow[J]. Journal of Engineering Thermophysics, 2015, 36(11): 2531-2535. 邵珺, 叶景峰, 李景银. 基于燃烧流场HTV技术的背景去除方法[J]. 工程热物理学报, 2015, 36(11): 2531-2535.
[29] Li S M, Lei G Q, Fan R. Depth map super-resolution reconstruction based on convolutional neural networks[J]. Acta Optica Sinica, 2017, 37(12): 1210002. 李素梅, 雷国庆, 范如. 基于卷积神经网络的深度图超分辨率重建[J]. 光学学报, 2017, 37(12): 1210002.
[30] Yu Q H, Wu D M, Chen F C, et al. Design of a wide-field target detection and tracking system using the segmented planar imaging detector for electro-optical reconnaissance[J]. Chinese Optics Letters, 2018, 16(7): 071101.
[2] Dam N, Klein-Douwel R J H, Sijtsema N M, et al. Nitric oxide flow tagging in unseeded air[J]. Optics Letters, 2001, 26(1): 36-38.
[3] Michael J B, Edwards M R, Dogariu A, et al. Femtosecond laser electronic excitation tagging for quantitative velocity imaging in air[J]. Applied Optics, 2011, 50(26): 5158-5162.
[4] Ribarov L A, Wehrmeyer J A, Hu S, et al. Multiline hydroxyl tagging velocimetry measurements in reacting and nonreacting experimental flows[J]. Experiments in Fluids, 2004, 37(1): 65-74.
[5] Pan F, Sánchez-González R, McIlvoy M H, et al. Simultaneous three-dimensional velocimetry and thermometry in gaseous flows using the stereoscopic vibrationally excited nitric oxide monitoring technique[J]. Optics Letters, 2016, 41(7): 1376-1379.
[6] Si Hadj Mohand H, Frezzotti A, Brandner J J, et al. Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion[J]. Experimental Thermal and Fluid Science, 2017, 83: 177-190.
[7] Chen F, Liu H, Li H X, et al. An experimental investigation with molecular tagging technique on the spray flow ejected from an air-blast nozzle[C]//AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Washington, D.C. Reston, VA: AIAA, 2015: 2016-3251.
[8] Zhang Z R, Zhu F, Li G H, et al. Research on spontaneous Raman scattering excited by XeF(C-A) laser[J]. Acta Optica Sinica, 2014, 34(11): 1114001. 张振荣, 朱峰, 李国华, 等. 基于XeF (C-A)激光激励的自发拉曼散射技术研究[J]. 光学学报, 2014, 34(11): 1114001.
[9] Zhang L R, Hu Z Y, Ye J F, et al. Mobile CARS temperature measurements at exhaust of supersonic combustor[J]. Chinese Journal of Lasers, 2013, 40(4): 0408007. 张立荣, 胡志云, 叶景峰, 等. 移动式CARS系统测量超声速燃烧室出口温度[J]. 中国激光, 2013, 40(4): 0408007.
[10] Wang S, Shao J, Li G H, et al. Multi-point velocity measurement of gas flow field based on detecting the Doppler frequency shift of molecular rayleigh scattering[J]. Chinese Journal of Lasers, 2015, 42(10): 1015002. 王晟, 邵珺, 李国华, 等. 基于检测分子瑞利散射光多普勒频移的流场多点速度测量[J]. 中国激光, 2015, 42(10): 1015002.
[11] Tao B, Ye J F, Zhao X Y, et al. Temperature measurement of instantaneous supersonic flow based on absorption spectroscopy technology[J]. Chinese Journal of Lasers, 2011, 38(12): 1215002. 陶波, 叶景峰, 赵新艳, 等. 基于激光吸收光谱技术测量瞬态超声速流场温度[J]. 中国激光, 2011, 38(12): 1215002.
[12] Zhang S H, Yu X L, Yan H, et al. Molecular tagging velocimetry of NH fluorescence in a high-enthalpy rarefied gas flow[J]. Applied Physics B, 2017, 123(4): 122.
[13] Raffel M, Willert C E, Wereley S T, et al. Particle image velocimetry. A practical guide[M]. Berlin, Heidelberg: Springer-Verlag, 2007.
[14] Ribarov L A, Wehrmeyer J A, Pitz R W, et al. Hydroxyl tagging velocimetry (HTV) in experimental air flows[J]. Applied Physics B: Lasers and Optics, 2002, 74(2): 175-183.
[15] André M A, Bardet P M, Burns R A, et al. Development of hydroxyl tagging velocimetry for low velocity flows[C]//AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Washington, D.C. Reston, VA: AIAA, 2015: 2016-3247.
[16] Pitz R W, Lahr M D, Douglas Z W, et al. Hydroxyl tagging velocimetry in a supersonic flow over a cavity[J]. Applied Optics, 2005, 44(31): 6692-6700.
[17] Lahr M D, Pitz R W, Douglas Z W, et al. Hydroxyl-tagging-velocimetry measurements of a supersonic flow over a cavity[J]. Journal of Propulsion and Power, 2010, 26(4): 790-797.
[18] Perkins A N, Ramsey M, Strickland D J, et al. Dual-pulse hydroxyl tagging velocimetry (HTV) in jet engine exhausts[C]// AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Denver, Colorado. Reston, VA: AIAA, 2009: 2009-5108.
[19] Zhang Z R, Li G H, Ye J F, et al. On-line measurement of species concentration in flow field of scramjet engine[J]. Optics and Precision Engineering, 2016, 24(4): 709-713. 张振荣, 李国华, 叶景峰, 等. 超燃发动机流场组分浓度的在线测量[J]. 光学精密工程, 2016, 24(4): 709-713.
[20] Li G H, Hu Z Y, Wang S, et al. 2D scanning CARS for temperature distribution measurement[J]. Optics and Precision Engineering, 2016, 24(1): 14-19. 李国华, 胡志云, 王晟, 等. 基于相干反斯托克斯拉曼散射的二维温度场扫描测量[J]. 光学精密工程, 2016, 24(1): 14-19.
[21] Ye J F, Hu Z Y, Liu J R, et al. Development and application of molecular tagging velocimetry[J]. Journal of Experiments in Fluid Mechanics, 2015, 29(3): 11-17, 61. 叶景峰, 胡志云, 刘晶儒, 等. 分子标记速度测量技术及应用研究进展[J]. 实验流体力学, 2015, 29(3): 11-17,61.
[22] Ye J F, Shao J, Li G H, et al. Vibration disturbance suppression in velocity measurements by hydroxyl tagging velocimetry[J]. Optics and Precision Engineering, 2017, 25(7): 1689-1696. 叶景峰, 邵珺, 李国华, 等. 羟基分子标记示踪速度测量中的强振动干扰抑制[J]. 光学精密工程, 2017, 25(7): 1689-1696.
[23] Gendrich C P, Koochesfahani M M. A spatial correlation technique for estimating velocity fields using molecular tagging velocimetry (MTV)[J]. Experiments in Fluids, 1996, 22(1): 67-77.
[24] Ramsey M C, Pitz R W. Template matching for improved accuracy in molecular tagging velocimetry[J]. Experiments in Fluids, 2011, 51(3): 811-819.
[25] van de Water W, Dam N. How to find patterns written in turbulent air[J]. Experiments in Fluids, 2013, 54(9): 1574-1583.
[26] Sanchez-Gonzalez R, McManamen B, Bowersox R D W, et al. A method to analyze molecular tagging velocimetry data using the Hough transform[J]. Review of Scientific Instruments, 2015, 86(10): 105106.
[27] Shao J, Ye J F, Hu Z Y, et al. Progressive approach characteristic window filtering for HTV background suppression in supersonic combustion field[J]. Optics and Precision Engineering, 2015, 23(10): 221-228. 邵珺, 叶景峰, 胡志云, 等. 用于超燃流场羟节标记示踪背景抑制的逐步逼近特征窗口滤波[J]. 光学精密工程, 2015, 23(10): 221-228.
[28] Shao J, Ye J F, Li J Y. A background removal approach to the study of hydroxyl tagging velocimetry in supersonic combustion flow[J]. Journal of Engineering Thermophysics, 2015, 36(11): 2531-2535. 邵珺, 叶景峰, 李景银. 基于燃烧流场HTV技术的背景去除方法[J]. 工程热物理学报, 2015, 36(11): 2531-2535.
[29] Li S M, Lei G Q, Fan R. Depth map super-resolution reconstruction based on convolutional neural networks[J]. Acta Optica Sinica, 2017, 37(12): 1210002. 李素梅, 雷国庆, 范如. 基于卷积神经网络的深度图超分辨率重建[J]. 光学学报, 2017, 37(12): 1210002.
[30] Yu Q H, Wu D M, Chen F C, et al. Design of a wide-field target detection and tracking system using the segmented planar imaging detector for electro-optical reconnaissance[J]. Chinese Optics Letters, 2018, 16(7): 071101.