摘要
In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young’s modulus on the turbulent drag reduction. The friction coefficients of flexible tubes with different Young’s modulus were examined by using a sleeve-tube structure. The fluctuating vibration of the outer wall and the fluctuating pressure on the inner wall of the tubes were measured with a laser displacement sensor and a pressure sensor. The results are as follows. The smaller the Young’s modulus of a flexible tube and the larger the Reynolds number, the larger the turbulent drag reduction rates become. The transition from laminar flow to turbulent flow can be delayed with an appropriate Young’s modulus. Non-dimensional amplitude of fluctuating vibration on the outer wall is smaller than that of a viscous sub-layer thickness, and is positively correlated with the friction drag reduction.
In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young’s modulus on the turbulent drag reduction. The friction coefficients of flexible tubes with different Young’s modulus were examined by using a sleeve-tube structure. The fluctuating vibration of the outer wall and the fluctuating pressure on the inner wall of the tubes were measured with a laser displacement sensor and a pressure sensor. The results are as follows. The smaller the Young’s modulus of a flexible tube and the larger the Reynolds number, the larger the turbulent drag reduction rates become. The transition from laminar flow to turbulent flow can be delayed with an appropriate Young’s modulus. Non-dimensional amplitude of fluctuating vibration on the outer wall is smaller than that of a viscous sub-layer thickness, and is positively correlated with the friction drag reduction.
基金
Project supported by the Natural Science Foundation of Hunan Province (Grant No. 09JJ6068)
