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Vol.11 No.2previousAA157- SP20 (AA158-159-160-161-162) NT94

Academic Articles
Regular Paper Vol.11 No.2 (2019) p. 92 - p.98
 

Relationship between frequency characteristic of turbulent velocity fluctuation and wall thinning rate by flow-accelerated corrosion

 

Tatsuru KANEKO1,*, Shinji EBARA1 and Hidetoshi HASHIZUME1

 
1 Tohoku Univ. Graduate School of Engineering, Dept. of Quantum Science and Energy Engineering, 6-6-01-2, Aramaki-aza aoba, Aoba-ku, Sendai 981-8579, Japan
 
Abstract
Flow-accelerated corrosion (FAC) causes a wide range of pipe wall thinning, and there is a risk that serious accidents are caused by significant pipe rupture and coolant leakage due to FAC. The purpose of this paper is to specify what kind of turbulence parameters affects wall thinning rate and to evaluate the influence of frequency characteristics of velocity fluctuations on wall thinning rate by conducting an accelerated wall thinning test using benzoic acid as thinning wall and a flow visualization test using sodium iodide solution and acrylic channel. Benzoic acid can simulate wall thinning of carbon steel in terms of mass transfer in high Schmidt number flow, and flow visualization was conducted by particle image velocimetry (PIV). From the evaluation of frequency characteristics of velocity fluctuation, it was found that the characteristic could not explain how large the wall thinning rate was. After scrutinizing the correlation between wall thinning rates and turbulent quantities, it was found that the total shear stresses composed of contribution by molecular viscosity and Reynolds stress evaluated not on and in the vicinity of the wall but also far from the wall have much to do with the wall thinning rate. In addition, the profile of the total shear stress to the power of 0.25 corresponds with that of wall thinning rate reasonably well.
 
Keywords
Pipe Wall Thinning, Flow-Accelerated Corrosion, Frequency Characteristic, Velocity Fluctuation, Shear Stress
 
Full Paper: PDF EJAM Vol. 11 No. 2 pp.92-98 "Relationship between frequency characteristic of turbulent velocity fluctuation and wall thinning rate by flow-accelerated corrosion"
Article Information
Article history:
Received 23 October 2018
Accepted August 2019