Numerical simulation of long-period fluid temperature fluctuation at a mixing tee for the thermal fatigue problem

Utanohara, Yoichi; Nakamura, Akira; Miyoshi, Koji; Kasahara, Naoto

doi:10.1016/j.nucengdes.2016.06.024

Cited by 23 publications

(9 citation statements)

References 8 publications

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“…Figure 5 demonstrates that regardless of the numerical simulation approach used in this region, the predicted results and the WATLON data [10] do not agree-the RANS approach underestimates the temperature value, while the LES approach overestimates it. As described in [19], the LES results obtained with the use of different computational meshes were not practically different and demonstrated the overestimated temperature value near the main pipe wall. The LES results [20,21], when the numerical simulation approach used the near-wall functions and the computational meshes were formed with the thermal boundary layer resolution, also showed the overestimated temperature value near the main pipe wall.…”

Section: Watlon Experiments Simulationmentioning

confidence: 69%

Non-Isothermal Vortex Flow in the T-Junction Pipe

et al. 2021

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The numerical simulation approach of heat carrier mixing regimes in the T-junction shows that the RANS approach is beneficial for a qualitative flow analysis to obtain relatively agreed averaged velocity and temperature. Moreover, traditionally, the RANS approach only predicts the averaged temperature distribution. This mathematical model did not consider the temperature fluctuation variations important for the thermal fatigue task. It should also be emphasized that unlike the LES approach, the steady RANS approach cannot express a local flow structure in intense mixing zones. Nevertheless, apparently the adopted RANS approach should be used for assessing the quality of computational meshes, boundary conditions with the purpose to take LES for further numerical simulation.

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Section: Watlon Experiments Simulationmentioning

confidence: 69%

Non-Isothermal Vortex Flow in the T-Junction Pipe

et al. 2021

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“…This may cause temperature and local stress effects to dominate [23]. A more uniform temperature mixture would exhibit less temperature fluctuation behaviour in a right-angled (α=90 o ) mixer [24]. As a result of the interaction of high and low momentum in the fluid structure, large-scale heat transfer has occurred [32] and a macro-structured mixture has formed in the results.…”

Section: Resultsmentioning

confidence: 99%

“…On the inner surface of the main pipe where the mixture joined, the local stress and temperature fluctuation range was measured as high. Thermal fatigue crack formation potential was investigated by considering the temperature fluctuation frequencies of the fluid close to the surface edges in mixing tees where hot and cold fluid mixtures take place [24]. A tmixer with a non-aligned inlet was examined considering the structure of the mixer inlet and its asymmetric flow [25].…”

Section: Introductionmentioning

confidence: 99%

Effect Of Taper Angle On Flow And Stress In Conical Shell Fluid Mixers

Yavuz¹

2021

Bitlis Eren Üniversitesi Fen Bilimleri Dergisi

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Hollow cylindrical flow mixers achieve a homogeneous mixture with less pressure loss and higher momentum. However, the low volume of the mixer due to the hollow creates high pressure effects and mechanical stresses on the mixer. In this study, the stresses formed on the mixer by considering the flow and thermal effects of fluids in a conical cylinder mixer at different temperatures were examined. The effect of taper angle has been studied. In the examinations carried out using the finite element method, a verification study was first made, and solution sensitivity was determined. Water as fluid in standard conditions and common steel properties as cylinder material were used. Plate thickness was chosen to be 1 mm. It seems more appropriate to use a non-conical straight model to achieve thermal equilibrium. The taper angle reduced the high velocity region created by the fluid entering the mixer. Stress concentrations were observed at the supports and a lower and decreasing stress distribution was obtained for the conical mixer while it was constant for the straight cylinder in the other regions.

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“…Temperature fluctuation through pipe wall and consequent stress fluctuations occur due to mixing of high-and low-temperature fluids. Thus, as discussed in [7], detailed thermal fatigue analysis is required for: ensuring fatigue limit is not exceeded, or in case it is exceeded then preforming fatigue crack growth analysis for initiated crack to estimate the remaining life of the component before leak or break.…”

Section: Introductionmentioning

confidence: 99%

Thermal transient finite element computation of a mixing Tee by utilizing CFD results

Saifi

Cronvall

2020

RakMek

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Thermal distribution and fluctuation in any piping component due to turbulent mixing of flows with different temperatures vary greatly. Usually, computational fluid dynamics (CFD) tools are used for estimation of flows in piping components. Fatigue that results from fluctuating thermal mass flow across the components can be computed by coupling the CFD results with structural mechanics based finite element (FE) results. However, this procedure is laborious and computationally very expensive. A fluid temperature function has been developed in this paper as a function of internal wall coordinates and time by interpolating experimental or CFD results. Bicubic interpolation function has been used for accurate interpolation. Finally, a thermal transient FE analysis for an actual Tee from a nuclear power plant (NPP) was performed by using the developed fluid temperature function and interpolated CFD results.

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Numerical simulation of long-period fluid temperature fluctuation at a mixing tee for the thermal fatigue problem

Cited by 23 publications

References 8 publications

Non-Isothermal Vortex Flow in the T-Junction Pipe

Non-Isothermal Vortex Flow in the T-Junction Pipe

Effect Of Taper Angle On Flow And Stress In Conical Shell Fluid Mixers

Thermal transient finite element computation of a mixing Tee by utilizing CFD results

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