周期性吹吸扰动对湍流边界层相干结构影响的实验研究
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摘要
本文应用热线测速技术,对风洞中平板湍流边界层壁面施加周期性吹吸扰动进行了试验研究。
实验采用IFA300恒温热线风速仪和X形二分量边界层热线探针精细测量了平板流动边界层,在施加不同频率的局部周期性吹吸扰动前后不同法向位置的瞬时流向、法向速度分量的时间序列信号。用子波变换对湍流脉动速度信号进行多尺度分解,用自相关法确定了不同尺度湍流结构的时间尺度。利用子波系数的瞬时强度因子、瞬时平坦因子和平坦因子检测平板湍流边界层中的多尺度相干结构。运用湍流多尺度相干结构的观点,来描述湍流局部多尺度湍涡结构相对迁移运动和局部多尺度变形的局部平均速度结构函数的平均波形,研究了多尺度相干结构猝发时流向速度分量、法向速度分量和瞬时雷诺应力分量的动力学发展、演化过程,并提出三者之间的相位关系。
通过平板底部表面沿展向切割一条5毫米宽的窄缝,用扬声器从壁面对平板湍流边界层施加不同频率的局部周期性吹吸扰动,通过改变平板湍流边界层中多尺度相干结构的发生概率、强度、能量分布、条件相位平均波形、间歇性等统计特征,对平板湍流边界层的不同尺度流动结构进行干扰和控制。研究不同频率的周期性扰动对平板边界层中的多尺度相干结构的影响。
In this paper, the technique of constant temperature anemometry, together with double-hot-wire-sensor probe, is used to carry out experimental study on the turbulent boundary layer, which is controlled by periodic blow-suction disturbance in the low turbulent level wind channel. In the experiment, time sequence of longitudinal velocity component and normal velocity component within and without different periodic blow-suction disturbance, along different normal positions in a flat-plate turbulent boundary layer has been finely measured by IFA300 constant temperature anemometer with resolution higher than Kolmogorov scale. The scales of multi-scale eddy structures are determined by self-correlation function. It is represented that the coherent structures and intermittency are identified by multi-scale flatness factor based on locally averaged velocity structure functions. Phased-average waveforms for longitudinal and normal fluctuation velocity, as well as Reynolds stress of multi-scale coherent eddy structures in turbulent boundary layer are extracted by this conditional sampling technique. The dynamic course of multi-scale coherent eddy structures’bursting is studied.
A periodic blowing/suction disturbance forcing, issued from a 5mm thin latitudinal slot of the flat, is introduced to alter multi-scale ingredients of coherent eddy structure and their energy distribution in turbulent boundary layer, what is more, to research the influence of periodic blowing/suction disturbance forcing on the multi-scale coherent structures in flat boundary layer. It is found that within periodic suction disturbance forcing, both the intensity and energy of coherent structures increase, moreover coherent structures at each scales are detected, in view of the changes of conditional phase-averaged waveforms for longitudinal and normal fluctuation velocity of multi-scale coherent eddy structures.
实验采用IFA300恒温热线风速仪和X形二分量边界层热线探针精细测量了平板流动边界层,在施加不同频率的局部周期性吹吸扰动前后不同法向位置的瞬时流向、法向速度分量的时间序列信号。用子波变换对湍流脉动速度信号进行多尺度分解,用自相关法确定了不同尺度湍流结构的时间尺度。利用子波系数的瞬时强度因子、瞬时平坦因子和平坦因子检测平板湍流边界层中的多尺度相干结构。运用湍流多尺度相干结构的观点,来描述湍流局部多尺度湍涡结构相对迁移运动和局部多尺度变形的局部平均速度结构函数的平均波形,研究了多尺度相干结构猝发时流向速度分量、法向速度分量和瞬时雷诺应力分量的动力学发展、演化过程,并提出三者之间的相位关系。
通过平板底部表面沿展向切割一条5毫米宽的窄缝,用扬声器从壁面对平板湍流边界层施加不同频率的局部周期性吹吸扰动,通过改变平板湍流边界层中多尺度相干结构的发生概率、强度、能量分布、条件相位平均波形、间歇性等统计特征,对平板湍流边界层的不同尺度流动结构进行干扰和控制。研究不同频率的周期性扰动对平板边界层中的多尺度相干结构的影响。
In this paper, the technique of constant temperature anemometry, together with double-hot-wire-sensor probe, is used to carry out experimental study on the turbulent boundary layer, which is controlled by periodic blow-suction disturbance in the low turbulent level wind channel. In the experiment, time sequence of longitudinal velocity component and normal velocity component within and without different periodic blow-suction disturbance, along different normal positions in a flat-plate turbulent boundary layer has been finely measured by IFA300 constant temperature anemometer with resolution higher than Kolmogorov scale. The scales of multi-scale eddy structures are determined by self-correlation function. It is represented that the coherent structures and intermittency are identified by multi-scale flatness factor based on locally averaged velocity structure functions. Phased-average waveforms for longitudinal and normal fluctuation velocity, as well as Reynolds stress of multi-scale coherent eddy structures in turbulent boundary layer are extracted by this conditional sampling technique. The dynamic course of multi-scale coherent eddy structures’bursting is studied.
A periodic blowing/suction disturbance forcing, issued from a 5mm thin latitudinal slot of the flat, is introduced to alter multi-scale ingredients of coherent eddy structure and their energy distribution in turbulent boundary layer, what is more, to research the influence of periodic blowing/suction disturbance forcing on the multi-scale coherent structures in flat boundary layer. It is found that within periodic suction disturbance forcing, both the intensity and energy of coherent structures increase, moreover coherent structures at each scales are detected, in view of the changes of conditional phase-averaged waveforms for longitudinal and normal fluctuation velocity of multi-scale coherent eddy structures.
引文
[1] 佘振苏,苏卫东,湍流中的层次结构和标度律 [J],力学进展,2000,29卷,第 3 期:289-303。
[2] Vincent A & Meneguzzi M, The spatial structure and statistical properties of homogeneous turbulence [J]. J. Fluid Mech. 1991, 225: 1-20
[3] She Z-S, Jackson E & Orszag S A, Intermittent vortex structures in homogeneous isotropic turbulence [J]. Nature 1990, 344: 226-228
[4] G. Ruiz Chavarria, S. Ciliberto, C. Baudet et al. Scaling properties of the streamwise component of velocity in a turbulent boundary layer, Physica D 141, 183-198.
[5] F. Toschi, G.Amiti, S. Succi et al. Intermittency and structure functions in channel flow turbulence, Physical Review Letters, Volume 32, Number 25, 5044-5047
[6] F. Toschi, E. Leveque, and G. Ruiz-Chavarria, Shear effects in nonhomogeneous turbulence, Physical Review Letters, Volume 85, Number 7, 1436-1439.
[7] R.Camussi, G.Guj, Orthonormal wavelet decomposition of turbulent flows: intermittency and coherent structures [J], J. Fluid Mech. (1997), vol. 348. pp 177-199.
[8] Ciguel Onorato, Roberto Camussi, Gaetano Iuso, Small scale intermittency and bursting in a turbulent channel flow, Physical Review E, Volume 61, Number 2, 1447-1454
[9] 姜楠,王振东,舒玮,辨识子波分析壁湍流猝发事件的能量最大准则 [J],力学学报,1997, 29(4):406-411。
[10] Kolmogorov A N, Dissipation of energy in the locally isotropic turbulence [J]. Dokl Akad Nauk SSSR, 1941, 32(1): 19-21.
[11] LIU Wei, JIANG Nan, Three Kinds of Velocity Structure Function in Turbulent Flows, CHIN.PHYS.LETT. Vol.21,No.10(2004):1989
[12] 黄永念,湍流与混沌之间关系的发展近况 [C],第三届全国湍流与流动稳定性学术会议论文集,第三届全国湍流与流动稳定性学术会议,天津,1991.1-6。
[13] King L V., On the convection of heat from small cylinders in a stream of fluid: Determination of the convection constants of small platinum wires with applications to hot-wire anemometry. Phil. Trans. Roy. Soc., 1914,A214, 373-432.
[2] Vincent A & Meneguzzi M, The spatial structure and statistical properties of homogeneous turbulence [J]. J. Fluid Mech. 1991, 225: 1-20
[3] She Z-S, Jackson E & Orszag S A, Intermittent vortex structures in homogeneous isotropic turbulence [J]. Nature 1990, 344: 226-228
[4] G. Ruiz Chavarria, S. Ciliberto, C. Baudet et al. Scaling properties of the streamwise component of velocity in a turbulent boundary layer, Physica D 141, 183-198.
[5] F. Toschi, G.Amiti, S. Succi et al. Intermittency and structure functions in channel flow turbulence, Physical Review Letters, Volume 32, Number 25, 5044-5047
[6] F. Toschi, E. Leveque, and G. Ruiz-Chavarria, Shear effects in nonhomogeneous turbulence, Physical Review Letters, Volume 85, Number 7, 1436-1439.
[7] R.Camussi, G.Guj, Orthonormal wavelet decomposition of turbulent flows: intermittency and coherent structures [J], J. Fluid Mech. (1997), vol. 348. pp 177-199.
[8] Ciguel Onorato, Roberto Camussi, Gaetano Iuso, Small scale intermittency and bursting in a turbulent channel flow, Physical Review E, Volume 61, Number 2, 1447-1454
[9] 姜楠,王振东,舒玮,辨识子波分析壁湍流猝发事件的能量最大准则 [J],力学学报,1997, 29(4):406-411。
[10] Kolmogorov A N, Dissipation of energy in the locally isotropic turbulence [J]. Dokl Akad Nauk SSSR, 1941, 32(1): 19-21.
[11] LIU Wei, JIANG Nan, Three Kinds of Velocity Structure Function in Turbulent Flows, CHIN.PHYS.LETT. Vol.21,No.10(2004):1989
[12] 黄永念,湍流与混沌之间关系的发展近况 [C],第三届全国湍流与流动稳定性学术会议论文集,第三届全国湍流与流动稳定性学术会议,天津,1991.1-6。
[13] King L V., On the convection of heat from small cylinders in a stream of fluid: Determination of the convection constants of small platinum wires with applications to hot-wire anemometry. Phil. Trans. Roy. Soc., 1914,A214, 373-432.