Experimental Study on Fluid Mixing for Evaluation of Thermal Striping in T-Pipe Junction

Abstract

A water experiment is performed to investigate thermal striping phenomena in a T-pipe junction which is a typical geometry of fluid mixing. The flow velocity ratio and temperature difference were experimental parameters. The jet form was classified into four patterns; (1) impinging jet, (2) deflecting jet, (3) re-attachment jet and (4) wall jet according to the inflow condition. The parameter experiments showed that the jet form could be predicted by a momentum ratio between the two pipes. The thermochromic liquid crystal sheet showed that a cold spot was formed at the wall surface in the main pipe in the cases of the impinging jet and the wall jet. From the temperature measurement in the fluid, temperature fluctuation intensity was high along the edge of the jet exiting from branch piping. A database of temperature fluctuation and frequency characteristics was established for an evaluation rule of thermal striping in a T-pipe junction.

Experimental study on fluid mixing phenomena in T-pipe junction with upstream elbow

“…From the flow visualization test, the flow patterns of jet exiting from the branch pipe could be classified into (1)wall jet, (2)deflecting jet, and (3)impinging jet according to the inflow condition. It was confirmed that each jet form could be predicted by momentum ratio of main to branch flows (Igarashi, 2002).…”

“…The velocity measurement was mainly carried out in the wall jet case and the temperature difference was zero (isothermal condition). The influence of buoyancy force was negligible under the velocity conditions of over 0.1m/s in the main pipe (Igarashi, 2002). The measurements were carried out under steady state condition; the flow rates and temperatures at the inlets of main and branch pipes were kept constant.…”

Simulation of turbulent and thermal mixing in T-junctions using URANS and scale-resolving turbulence models in ANSYS CFX

“…in pipelines in power plants. Recent studies using advanced scale-resolving methods such as LES and DES have shown promising results ( [3], [5], [6], [7], [12], [15] and [17]). However, detailed validation of the tools and methods is still required in order to determine their range of validity and their expected accuracy.…”

Thermal Mixing in T-Junction Piping System Related to High-Cycle Thermal Fatigue in Structure

“…Thus, thermal striping may be an issue for the CIP and has been recognized as one of the most important issues in design and safety of the JSFR. [2][3][4] In JAEA, experiments [4][5][6][7][8] and numerical analyses 3,[9][10][11] have been performed in order to evaluate thermal striping phenomena and to establish an evaluation ÓAtomic Energy Society of Japan method for the high-cycle thermal fatigue in JSFR. As for the evaluation method, Kasahara et al 12) proposed a thermal fatigue evaluation method based on power spectrum density (PSD) of temperature fluctuation in a fluid and a frequency transfer function from the fluid temperature fluctuation to thermal stress in the structure.…”