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Turbulence prediction using the large eddy simulation method in staggered and inlined bundles
Abstract
Due to the high probability of tube fracture within bundles in heat exchangers, the study of the effects of turbulent flow are a major concern in the power industry. Extensive studies to understand turbulent flow characteristics have been made both experimentally and computationally. The need for computational studies have risen due to the expensive cost of experimental studies. Also, the amount of information available for a computational study is more than that of an experimental study. In this investigation a computational technique has been used to study fluid flow phenomena in tube bundles of different geometries. The method used is the large eddy simulation technique. Large eddy simulation may be defined as any simulation of a turbulent flow in which the large scale motions are explicitly resolved while the small scale motions are modeled. This results into a system of equations that require closure models. The closure models relate the effects of the small scale motions onto the large scale motions. There have been several models developed, the most popular is the Smagorinsky eddy viscosity model. A new model has recently been introduced by Lee that modified the Smagorinsky model. Using both of the above mentioned closure models, two different geometric arrangements were used in the simulation of turbulent cross flow within rigid tube bundles. Staggered arrays were used in deep bundle simulations of two-dimensions (27,412 nodes) and three-dimensions (210,600 nodes). Comparisons were made to available experimental data with good agreement. Flow visualization enabled the distinction of different characteristics within the flow such as switching effects. Inlined array simulations was also performed for a deep bundle (10,816 nodes) as well as an inlet/outlet simulation (57,600 nodes), and results were compared to that of experimental data. Reasonable agreement was obtained. Here too, flow characteristics provided observations of the jet switching effects in the wake of the bundle flow for the inlet/outlet simulation case. The results indicate that the large eddy simulation technique is capable of turbulence prediction and may be used as a viable engineering tool with the careful consideration of the subgrid scale model.
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Citation
Barsamian, Hagop Raffi (1994). Turbulence prediction using the large eddy simulation method in staggered and inlined bundles. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -B282.
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