Abstract
The development of steady, turbulent flow in a 90° section of a curved square duct was studied at a Reynolds number of 4 × 104 by hot-wire anemometer. The curved duct has a cross-section measuring 80 × 80 mm and a curvature radius ratio of 4 and is connected with a long, straight duct at its both ends. The longitudinal and lateral components of mean and fluctuating velocities, and the Reynolds stresses were measured by the method of rotating a probe with an inclined hot-wire. The velocity fields of the primary and secondary flows, and the Reynolds stress distributions in the cross-section were illustrated in the form of contour map. The development of the primary flow was found to be connected with a strong pressure gradient near the outer and inner wall and a secondary flow induced in the cross-section of the bend by a pressure difference between the outer and inner wall and a centrifugal force acting on the fluid; the fluid is accelerated near the inner wall and decelerated near the outer wall between the bend angle ϕ ≅ 0° and ϕ ≅ 30°, but an increase and decrease of the fluid velocity are reversed between ϕ ≅ 30° and ϕ ≅ 90°. The fluctuating velocity correlations, i.e. the Reynolds stresses follow a complicated progress according to the complex development of the primary flow. The results obtained can be available to verify various types of turbulence models and to develop new models.
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Received: 10 May 1999/Accepted: 15 March 2000
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Sudo, K., Sumida, M. & Hibara, H. Experimental investigation on turbulent flow in a square-sectioned 90-degree bend. Experiments in Fluids 30, 246–252 (2001). https://doi.org/10.1007/s003480000157
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DOI: https://doi.org/10.1007/s003480000157