Simulação numérica do escoamento turbulento em canais compostos utilizando condição de periodicidade

• Autor(a) principal: Sant' Ana, Sílvia Patrícia Calixto de Lira
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/42980
• topic: canal composto; estrutura coerente; simulação numérica; transferência de calor

Compound channels have different regions and the flow will behave in different ways on each of them. In the wider regions, called main channels, the fluid flows more easily. Those regions are connected by a gap, where the fluid is decelerated due to viscous forces, resulting in shear flows. The fluid flows axially and the presence of this gap causes the appearance of large scale structures called coherent structures, that induce a cross flow velocity, which, consequently, modifies the turbulent flow. In a result, the heat transfer process is changed. This work aims to analyze the effects caused by the presence or absence of the coherent structures, both in dynamic part as thermal. Thus, a rectangular compound channel with an inner tube of diameter D was used, in which the gap size was the variable parameter. The fluid flows axially only on the outside of the tube. Three cases were analyzed, wherein the distance W/D (gap size) varied. The simulations were conducted in software ANSYS CFX and the turbulence model used was SAS SST. As a result, it was verified the appearing of the coherent structures in two cases. The modification in the flow and in heat transfer process was confirmed on each of them. Therefore, it is essential the investigation and study about the appearing of those structures in a project, even for reasons of operational safety.