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|Cartesian mesh applied to thermal flow simulations of high power air cooled industrial LED lamps|
|Keywords: cartesian mesh, led , thermal management|
|June 17, 2015 Technical problem description Evaluate the thermal behavior of a UV LED lamp with a commercial CFD package presents some challenges: the air flow is often complex to satisfy the machine ambient requirements in which they have to operate; the LED package has to be detailed enough to calculate the exact temperature. On the one hand side we have relatively voluminous plenum and on the other side we have structures of 100 μm both to be meshed correctly taking into account the limitations the workstation hardware imposes. Another boundary is the time. An engineer can often not afford to spend days before knowing the result of a lamp configuration simulation, and the result has to be robust. In the past Cartesian mesh fulfilled many of the above mentioned requirements but were defective in curved surface approximation and/or detail catching. At the beginning of the year 2000, Cartesian mesh based software, for example EFD was unsatisfactory when employed with complex models. The last decade witnessed a revival of interest in Cartesian mesh methods for CFD. In contrast to the body-fitted structured or unstructured methods, Cartesian grids are inherently non-body-fitted, i.e.: the volume mesh structure is independent of the surface discretization and topology. This characteristic promotes extensive automation, eases the burden of surface preparation, and simplifies the re-analysis processes whenever the topology of a configuration changes. Typically, meshes with millions of cells can be generated in minutes on moderately powerful workstations. The recent releases of CFD software which employ Cartesian mesh are much more efficient and require less manual intervention in the initial meshing parameters, hence saving many working hours trying to refine a mesh that is within the limits of the computing hardware and the required solution precision. Case Study This paper will discuss a case of a Cartesian meshing for thermal flow simulation of a standard air cooled LED lamp and how it was possible to simulate it with precision and time effectively. UV Industrial LED lamps are specifically challenging due to the high heat power concentration (up to 3W/mm2 heat density, which means an equivalent 300 W/cm2). We will examine the air flow simulation solution, the solid/fluid boundary, the coherence of the thermal transmission in solids and the output precision.|
|ing. Enrico Brega, Thermal Management Engineer