Computation of turbulent flow in an IFRF quarl burner


Autoria(s): Kelson, Neil A.; McElwain, Sean; Truelove, John
Data(s)

01/12/1996

Resumo

A computational model for isothermal axisymmetric turbulent flow in a quarl burner is set up using the CFD package FLUENT, and numerical solutions obtained from the model are compared with available experimental data. A standard k-e model and and two versions of the RNG k-e model are used to model the turbulence. One of the aims of the computational study is to investigate whether the RNG based k-e turbulence models are capable of yielding improved flow predictions compared with the standard k-e turbulence model. A difficulty is that the flow considered here features a confined vortex breakdown which can be highly sensitive to flow behaviour both upstream and downstream of the breakdown zone. Nevertheless, the relatively simple confining geometry allows us to undertake a systematic study so that both grid-independent and domain-independent results can be reported. The systematic study includes a detailed investigation of the effects of upstream and downstream conditions on the predictions, in addition to grid refinement and other tests to ensure that numerical error is not significant. Another important aim is to determine to what extent the turbulence model predictions can provide us with new insights into the physics of confined vortex breakdown flows. To this end, the computations are discussed in detail with reference to known vortex breakdown phenomena and existing theories. A major conclusion is that one of the RNG k-e models investigated here is able to correctly capture the complex forward flow region inside the recirculating breakdown zone. This apparently pathological result is in stark contrast to the findings of previous studies, most of which have concluded that either algebraic or differential Reynolds stress modelling is needed to correctly predict the observed flow features. Arguments are given as to why an isotropic eddy-viscosity turbulence model may well be able to capture the complex flow structure within the recirculating zone for this flow setup. With regard to the flow physics, a major finding is that the results obtained here are more consistent with the view that confined vortex breakdown is a type of axisymmetric boundary layer separation, rather than a manifestation of a subcritical flow state.

Formato

application/pdf

Identificador

http://eprints.qut.edu.au/93455/

Publicador

Queensland University of Technology

Relação

http://eprints.qut.edu.au/93455/1/1996-kelson-etal-TR-96-5-computation%20of%20turbulent%20flow%20in%20an%20IFRF%20quarl%20burner.pdf

Kelson, Neil A., McElwain, Sean, & Truelove, John (1996) Computation of turbulent flow in an IFRF quarl burner. Queensland University of Technology.

Direitos

Copyright 1996 Queensland University of Technology

Fonte

Division of Technology, Information and Learning Support; High Performance Computing and Research Support; School of Mathematical Sciences; Science & Engineering Faculty

Palavras-Chave #091501 Computational Fluid Dynamics #091508 Turbulent Flows
Tipo

Report