力学与实践 ›› 2006, Vol. 28 ›› Issue (1): 0-0.DOI: 10.6052/1000-0879-2005-125

• 应用研究 •    

输气管道壁面涂料减阻机理的实验研究

姜楠 孙伟   

  1. 天津大学力学系,天津 天津大学力学系,天津
  • 收稿日期:2005-03-29 修回日期:2005-05-23 出版日期:2006-02-10 发布日期:2006-02-10

EXPERIMENT OF SURFACE COATING DRAG REDUCTION MECHANISM IN GAS TRANSPORTATION PIPE

  • Received:2005-03-29 Revised:2005-05-23 Online:2006-02-10 Published:2006-02-10

摘要: 用IFA-300热线风速仪以高于对应最小湍流时间尺度的分辨率精细测量了风洞中不同壁面 涂料的管道湍流边界层不同法向位置流向速度分量的时间序列信号,利用湍流边界层近壁区 域对数律平均速度剖面与壁面摩擦速度、流体黏性系数等内尺度物理量的关系和壁面摩擦速 度与壁面摩擦切应力的关系,在准确测量湍流边界层近壁区域对数律平均速度剖面的基础 上,间接测量湍流边界层的壁面摩擦阻力. 对不同壁面涂料的壁湍流脉动速度信号用子波分 析进行多尺度分解,用子波系数的瞬时强度因子和平坦因子检测管道湍流边界层中的多尺度 相干结构,提取不同尺度相干结构的条件相位平均波形,对比研究输气管道壁面涂料的减阻 机理.

关键词: 输气管道,壁面涂料,减阻,相干结构, 子波分析

Abstract: The velocity time sequence at different vertical locations in a turbulent pipe flow with different surface coating was carefully measured by IFA300 constant-temperature anemometer with a resolution higher than the frequency with respect to Kolmogorov dissipative scale. A method is put forward to calculate the skin friction velocity by means of nonlinear iteration, in order to achieve a non-perturbed or micro-perturbed measurement of wall shear stress. The relationship among some inner-scale physical parameters, e.g., the mean-velocity profile, skin friction velocity and fluid dynamics viscosity, and the relationship between skin friction velocity and skin friction shear stress were used in accurately calculating the skin friction drag based on the precise measurement of logarithmic mean-velocity profile in the near wall region of turbulent boundary layer. The velocity signals were decomposed into multi-scale eddy structures by wavelet transform. A conditional sampling technique for the multi-scale coherent eddy structure detection from the simultaneous turbulent field was introduced using the multi-scale instantaneous intensity factor and multi-scale flatness factor of wavelet coefficients. Coherent eddy structures for different scales were extracted by this technique and the mechanism of surface coating drag reduction is investigated for gas transportation of turbulent pipe flow.

Key words: transportation turbulent pipe flow, surface coating, drag