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Vol.4 No.4 previous AA-SP8(49-50-51-52-53-54-55-56-57-58)-NT 53 -54-55

Academic Articles
Regular Paper Vol.5No.1 (2013) p.34 - p.41
 

Experimental Study of Influence of Elbow Curvature on a Swirling Flow Generated in a Three-Dimensionally Connected Dual Elbow

 
Tatsuya KUBO 1,*, Shinji EBARA 1 and Hidetoshi HASHIZUME 1
 
1Tohoku University, 6-6-01-2, Aramaki-aza-aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan
 
Abstract
Since it was reported that Flow-accelerated corrosion was largely influenced by a swirling flow, it is important to clarify the characteristics of swirling flows formed in pipings. In this study, a flow experiment with 2D-PIV measurement was conducted in order to evaluate the swirling flow generated downstream of a three-dimensionally-connected dual elbow which comprises two 90-degree elbows directly connecting to each other. The ratio of the elbow curvature radius to a pipe inner diameter,Υ , was varied as an important parameter, and three types of elbow, Υ = 1.0, 1.5, 2.0, were tested. The Reynolds number was set at 300,000 and the inlet flow condition was fully developed turbulent flow. Experimental results showed that the swirl number of the swirling flow generated in the dual elbow became high and fluctuated largely as the cross-section where the swirl number was evaluated moved downstream of the elbows when Υ was small. In addition, high velocity secondary flows were likely to appear locally downstream of the elbows when Υ was small. In the parallel cross-section to the pipe axis, the high velocity area formed not in an island-like shape but in a belt-like one. The locally high velocity component in the circumferential and the axial direction implied formation of a spiral flow downstream of the dual elbow. And the spiral flow became strong when Υ = 1.0. Moreover the swirl numbers at the outlet of the second elbow were approximately same as that 8D downstream of the dual elbow in all of the cases, and the swirling flow was less likely to decay compare to the secondary flow generated in the single elbow and the dual elbow with a 2D-straight part between the elbows.
 
Keywords
Ageing Management, FAC, Degradation
 
Full Paper: PDF EJAM Vol.5No.1 pp.34-41 "Experimental Study of Influence of Elbow Curvature on a Swirling Flow Generated in a Three-Dimensionally Connected Dual Elbow "

















Article Information
Article history:
Received 12 November 2012
Accepted 20 February 2013