Simulação numérica do escoamento turbulento em canal composto
Compound channels are characterized by having main channels, wider regions where the fluid flows axially more easily, and narrower regions (gaps) where the fluid is decelerated due to the viscous effects. In order to determine the heat transfer coefficients in these channels it is necessary to un...
Na minha lista:
| Autor principal: | |
|---|---|
| Outros Autores: | |
| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Brasil
|
| Assuntos: | |
| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/23691 |
| Tags: |
Adicionar Tag
Sem tags, seja o primeiro a adicionar uma tag!
|
| Resumo: | Compound channels are characterized by having main channels, wider regions
where the fluid flows axially more easily, and narrower regions (gaps) where the fluid
is decelerated due to the viscous effects. In order to determine the heat transfer
coefficients in these channels it is necessary to understand the behavior of the
turbulent flows in them, but this remains a challenge for engineering. These channels
have, in addition to axial flow parallel to the channel, a cross flow velocity in the gap
region that are associated with large scale structures called coherent structures.
Thus, the goal of this work is to compare the effects on the appearance of coherent
structures of large scale and its consequences for the flow in dynamic and thermal
characteristics. To accomplish this, the same geometry used in the experimental
works was applied, which is composed of a rectangular channel with an internal tube
of diameter D and it is located at a distance W/D from the lower wall of the channel.
The fluid flows axially only on the outside of the tube. In total, five different cases
were analyzed, modifying only the W/D ratio (gap distance). To examine the
characteristics of the turbulent flow inside this channel, ANSYS CFX13 with SASSST
turbulence model was applied. The results showed that the W/D ratio increase
also caused an increase in the values of the Thermal Performance Factor. This factor
is a relationship between the Nusselt number and the friction factor, and the higher
its value, better is the thermal performance of the channel. In relation to the coherent
structures, in the channels in which they arise, they have a great influence on the
flows, since these structures end up raising the local values of heat transfer and
friction coefficients, making this phenomenon indispensable in projects and safety
analyzes of equipment with gap. |
|---|