Master thesis work - Developing a numerical model of a physical climate chamber in commercial CFD software, ANSYS Fluent. The baseline numerical model was further validated using the experimental tests data. The experiments were conducted inside the climate chamber using ultrasonic anemometers, thermocouples and a mock-up radio unit, that would act as a heat generating source. The climate chamber is used to carry out reliability tests on the telecommunication prototypes, before they released out in the market.
For each generation of electronic equipment there is a trend towards higher power densities. Increased heat generation is an undesired consequence that the thermal design unit in a company must handle. The goal of thermal design engineer/unit is to utilize the same volume to more efficiently transfer more heat from the equipment. This can be done by exploringmore complex and advanced heat sink geometries, optimizing the fin shapes and so on. The new prototypes developed will be tested for their reliability and endurance in special chambers called climate chambers, that simulate desired environments. The measurements by thermal design teams in these kind of climate chambers are mainly of outdoor products, whose cooling is based on natural convection. Forced cooling using fans is optional for these outdoor products.
The climate chambers in general provides temperature measurement as the output to the analysis, though there are other important parameters that define the operational functionality of an equipment. The ability to visualize the flow characteristics during the process of testing is a valuable aid in the design process. A virtual/CFD form of the physical climate chamber (CC) would empower the design process, while alleviating the usage of the climate chambers for such analyses. CFD offers a wide range of capabilities that lets the user change the boundary conditions with great ease compared to that of the experimental setup.
The numerical model developed in this thesis project provides results, that help in understanding the physics involved in fluid flow inside the physical climate chamber. Turbulence quantification of the flow is the main aim of this thesis project, which would be resourceful in future works. Experiments are conducted inside the climate chamber, in order to aid the construction of numerical model as well as serve as source of validation for the numerical results. Laminar transient case simulations are preferred over use of any turbulence models, to limit any kind of predictions made by these turbulence models. Integral length scales and turbulence intensities are compared and reason for discrepancies are addressed. The results from the comparisons show that, the numerical model emulates physics of actual flow inside the climate chamber. However, there are many factors that directly affect the results, making it difficult to precisely quantify the error, within the time period of this thesis project.
Keywords: Climate chamber, Computational fluid mechanics, turbulence, thermal design, turbulence spectra, Energy Density Spectrum, Integral length scales, Turbulent intensity