Turbulence radiation interactions in a fully developed channel flow

Turbulence radiation interactions in a fully developed channel flow

Silvestri, S.

Pecnik, R. (mentor)

Mechanical, Maritime and Materials Engineering

Process and Energy

Sustainable Process and Energy Technology

2016-02-26

Radiative heat transfer plays an important role in many industrial applications, particularly when high temperature heat transfer is involved. Many theoretical analysis and experimental investigations have shown the occurrence of interactions between radiation quantities and turbulence, mainly due to the non-linearity between radiative heat transfer and the temperature field. Turbulence Radiation interactions (TRI) are characterized by the effect of turbulence on radiation and vice versa the influence of radiation in the modification of the turbulence field. While the first effect of TRI has been extensively studied, a comprehensive understanding of the effect of radiation on temperature variance is still lacking. In addition radiative heat transfer, and thus TRI, present largely different effects based on the optical thickness of the participating media. Therefore, a thorough study regarding the impact of the optical thickness of the flow in characterizing TRI is required. The present work consists of an investigations of TRI in a non reactive turbulent channel flow based on three optical depths (? = 0.1,1,10). A Finite Volume Method for radiative heat transfer has been implemented and coupled with a DNS code for turbulent channel flow. A fictitious fluid has been simulated with both grey properties and variable absorption coefficient based on the Planck mean absorption coefficient of water vapour. The effects of radiation on the thermal fluctuation field are described and discussed. The results show a strong impact of the optical thickness of the media on the temperature fluctuation field, depicting a transition in TRI behaviours. While for a low value of optical depth (? ), a dissipative effect of TRI on temperature variance is reported, for high optical thicknesses the appearance of large thermal structures in the core of the channel is observed. In particular the distinct and contrasting role of absorption and emission in modifying temperature variance is highlighted and analyzed. In addition the study of TRI is parametrized on the Planck number. While a strong impact in the temperature field is noticed, the characteristics of TRI are not modified with a change in the Planck number

Radiation
Turbulence
DNS
FVM

http://resolver.tudelft.nl/uuid:503e1c2c-96fe-4eec-b8cd-c9b37ee77abb

Student theses

master thesis

(c) 2016 Silvestri, S.