The effect of inlet flow conditions upon thermal mixing and conjugate heat transfer within the wall of a T-Junction

Lampunio, Lisa; Duan, Yu; Eaton, M.D.

doi:10.1016/j.nucengdes.2021.111484

Cited by 7 publications

(14 citation statements)

References 36 publications

(45 reference statements)

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“…Cases '0-20', '0-40', and '0-60' show similar profiles, with the velocity peaking at the centre of the pipe. The fact that case '0-20' presents the highest velocity among all cases could explain the lower value of T * at the top and side of the pipe for this case (see Figure 7b-d) as also suggested in [33]. Comparing the cases with uniformly distributed profiles at the main pipe with the cases with fully developed profiles at the main inlet, the overall values are slightly higher than the ones obtained with uniformly distributed BCs.…”

Section: Profiles Of Mean Temperature and Velocitysupporting

confidence: 67%

“…These simple assumptions may lead to different mean and transient flow behaviours and hence result in different mean temperature distributions and temperature fluctuations at the pipe wall. These temperature fluctuations may lead to temperature oscillations with frequencies in the range of high cycle thermal fatigue as shown in our previous studies [33][34][35]37,38].…”

Section: Description Of the Cfd Modelsmentioning

confidence: 53%

“…The IDDES-SST is a hybrid RANS/LES model which uses RANS close to the wall and LES in the bulk flow. The RANS and LES regions across the computational model are shown in [33] for different mesh sizes and in [37] for different BCs.…”

Section: Description Of the Cfd Modelsmentioning

confidence: 99%

“…x ≈ 80. The results of the mesh sensitivity study and model validation are reported in [33]. To reduce the numerical error, the most refined computational mesh is used for the rest of the discussion.…”

Section: Description Of the Cfd Modelsmentioning

confidence: 99%

“…In ref. [33], it is shown that the inlet flow profiles of the BCs at the branch inlet have the most significant impact on the thermal mixing downstream of the T-junction. To further understand the flow physics behind this observation, uniformly distributed BCs, indicated with the index '0', and profiles extracted at 5, 10, 20, 40, and 60 diameters from the inlet flow profile generator of the branch inlet pipe are considered as the inlet of the branch pipe of the T-junction (branch inlet for short).…”

Section: Description Of the Cfd Modelsmentioning

confidence: 99%

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Mean Flow, Turbulent Structures, and SPOD Analysis of Thermal Mixing in a T-Junction with Variation of the Inlet Flow Profile

et al. 2022

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This paper investigates the effects of different inlet flow profiles on thermal mixing within a T-junction using CFD simulations with the IDDES-SST turbulence model. The different combinations of inlet flow profiles are related to different stage in the flow entry region. The effects of the inlet flow profile on the mean and transient flow behaviour are assessed, while a spectral proper orthogonal decomposition and power spectral density analysis are performed to assess the underlying flow structures and the predominant frequency modes. It is found that the vortical structures associated with the horseshoe and hovering vortex systems consist of a single roll-up vortex for cases with uniformly distributed boundary conditions (BCs) at the branch inlet whereas a double roll-up vortex is observed for the other cases. The double roll-up vortex enhances the mixing locally due to the entrainment of fluid from the branch pipe in these vortical structures, which then results in a lower mean temperature distribution. The appearance of the secondary vortex pair and the nested vortices is delayed for cases with uniformly distributed BCs at the branch inlet, which again results in lower thermal mixing and consequently higher values of mean temperature when compared with the other cases. It is also found that the vorticity related to the counter-rotating vortex pair as well as to the second pair of vortices rotating in the opposite direction is higher for cases with uniformly distributed BCs at the branch inlet. Lastly, the combinations of inlet flow profiles lead to different coherent structures, and the dominant frequencies are of a Strouhal number of around 0.7 for uniformly distributed profiles at the branch inlet and in the range 0.4–0.5 for the other cases.

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Section: Profiles Of Mean Temperature and Velocitysupporting

confidence: 67%