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Master thesis : Implementation in OpenFoam of a thermal-fluid analysis for

thermal internal flows

Auteur : Martinez Carrascal, Jon

Promoteur(s) : Terrapon, Vincent

Faculté : Faculté des Sciences appliquées

Diplôme : Master en ingénieur civil en aérospatiale, à finalité spécialisée en "aerospace engineering"

Année académique : 2016-2017

URI/URL : http://hdl.handle.net/2268.2/3315

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February - August 2017University of Liege

Faculty of Applied SciencesMaster Thesis

Implementation in OpenFoam of thermal-fluid analysis forinternal flows

AuthorIndustrial tutorAcademic Advisor

Martínez JonSalvador Lucas

Terrapon Vincent

Summary: A CFD analysis of the flow inside of the VMU MkII in micro-gravityconditions is presented. In the context of complementing the different calculations madeby CSL professional using the ESATAN-TMS software, this thesis will contribute to sup-port the existing data of the unit regarding the airflow and the components of the VMU.

After considering the characteristics and conditions of the flow inside this unit, themathematical formulation of the problem is proposed. Then, the numerical implementa-tion is presented and for this task, the finite volume method OpenFOAM software is used.

A CAD model of the VMU MkII is been loaded and re-built using the SALOME soft-ware. After the model is meshed using the snappyHexMesh OpenFOAM utility, a meshconvergence study has been performed defining the mesh where the final results will beobtained.

The results of the thesis display an impact of the bottom rails of the FPIU of 60% inthe velocity field and a maximum discrepancy in velocity of 22.37% between the k − ω

and k − ω SST turbulence models. On the other hand, it is observed that the meantemperatures of the components surpass the thermal requirements of the VCU by 4.2K

for the VCU, by 53.38K for the CPU and by 97.95K for the SA50-120 modules. Also,the sensitivity analysis for the turbulent intensity at inlets shows that a 1% variationof the turbulent intensity at the inlets gives rise to an average variation of the velocitymagnitude of 0.07%.

As a conclusion, it is important to underline that the inclusion of conduction in themodeling and a different power distribution may be the reason why the mean tempera-tures of the components are overestimated. Also, due to the lack of solid experimentaldata it is not possible to confirm which turbulence model is more suitable for the case ofstudy. Finally, the small variations of the solution due to the sensitivity analysis may bean indicator that the boundary condition for the turbulent kinetic energy at the inlets iswell posed.

Keywords: RANS, solver, OpenFOAM, Finite-Volume method, heat transfer, forcedconvection.

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Figure 1: Front 2D plot of the velocity field in m/s inside the FPIU displaying the vectorfield (left) and isolines (right).

Figure 2: Velocity profile of the flow through the HDD slots. Counting from 1 to 4 fromleft to right.

Figure 3: Left side 2D plot of the velocity field in m/s inside the FPIU (CPU slot)displaying the vector field (left) and isolines (right).

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Figure 4: Transversal cut of the VMU showing the velocity field in m/s displaying thevector field (left) and isolines (right).

Figure 5: 3D view of the streamlines of the airflow inside the VMU MkII. General view(left) and top view (right).

Figure 6: 3D view of the temperature distribution (in K) of the CPU and the heatex-changer.

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Figure 7: 2D plot of the temperature distribution (in K) and velocity vector field (inm/s) of the SA50-120 modules.

Figure 8: Temperature profile of the flow (in K) through the 11 fins of the VCU.

Figure 9: Specific turbulent kinetic energy field (in m2/s2) and velocity field isolines (inm/s) inside the FPIU.

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Figure 10: Transversal cut of the VMU displaying the velocity vector field (in m/s) with(right) and without (left) the mid-stiffener.

Figure 11: 2D cut of the FPIU displaying the velocity isolines (in m/s) with (right) andwithout (left) the FPIU bottom rails.

Figure 12: Velocity profile (in m/s) of the flow in the cross-section of the mid-stiffenerfrom the left wall to the right wall of the VMU for the k − ω and k − ω SST turbulencemodels.

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Figure 13: Velocity profile (in m/s) of the flow across the HDD slots from 1-4 from leftto right, for the k − ω and k − ω SST turbulence models.

Figure 14: Turbulent kinetic energy profile (in m2/s2) at the left duct for turbulentintensities of 1%, 2%, 3%, 4% and 5%.

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Figure 15: Velocity profile (in m/s) at the left duct for turbulent intensities of 1%, 2%,3%, 4% and 5%. General plot (left) and zoomed plot (right).

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