Conjugate heat transfer analysis of an impingement/effusion cooled combustor liner

Yoko, Matthew Jonathan (2020-03)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: The design of gas turbine combustors is a costly, iterative process which is heavily reliant on empirical modelling. To facilitate the design of novel low emissions combustors, a multi-fidelity design process has been proposed. In this process, physics-based low order models are built; calibrated by high fidelity simulations and then used in multi-objective optimisation studies. The current work contributes to this process by providing a method of performing high fidelity multiphysics simulations of an impingement/effusion cooling scheme for a combustor liner wall. A conjugate heat transfer CFD model was used to capture details of the combusting flow field and its interaction with the liner wall. While this method has been successfully applied to pure effusion cooling, it had not yet been used to study impingement/effusion cooling in a representative combustor. Further to this, the impact of radiation modelling was investigated as this had not been considered in previous work. The method was validated against a simple experimental case study before being applied to a representative gas turbine combustor. It was shown that this method is capable of predicting impingement/effusion cooling performance to within 1% for a simple case. The combustor case study revealed a number of 3D effects which had not been captured by the low order model, most notably a strong interaction between the swirling flame and the cooling film. This informed recommendations for improvements to the low order model. It was further shown that radiative heat flux contributed up to 33% of the total flux, justifying the inclusion of radiation modelling in these studies. Finally, a strong sensitivity to the level of soot fouling was shown, with a potential doubling of radiative heat flux as a result. Further work is required to estimate the level of soot fouling on the liner walls, allowing the liner emissivity distribution to be more reliably constructed.

AFRIKAANSE OPSOMMING: Om gasturbiene verbranders te ontwerp is 'n duur en iteratiewe proses wat afhanklik is van empiriese modellering. Die ontwerp van nuwe, lae emissie verbranders kan vergemaklik word deur 'n ontwerpsproses te volg wat op verskeie vlakke van akkuraatheid staat maak. Hierdie proses behels die ontwikkeling van lae orde fisika modelle, wat gekalibreer word met hoë akkuraatheid simulasies, en dan gebruik word in veeldoelige optimeringsstudies. Die huidige werk dra by tot hierdie proses deur 'n metode vir hoë akkuraatheid multi-fisika simulasies van 'n impak/effusie verkoelingsskema van 'n verbrander voering te verskaf. Die besonderhede van die ontbrandende vloeiveld en die se interaksie met die voering word vasgevang in 'n gekoppelde warmte-oordrag be- rekeningsvloeidinamika model. Hierdie metode is in die verlede reeds suksesvol gebruik om suiwer effusie verkoeling te bestudeer, maar is tot dusver nog nie gebruik om impak/effusie verkoeling in 'n verteenwoordigende verbrander te on- dersoek nie.Die bydrae van straling word ook in die modelering ondersoek, wat nog nie voorheen bestudeer is nie. Die geldigheid van die metode word bevestig deur dit te vergelyk met 'n eenvoudige eksperimentele gevallestudie voor dit op 'n verteenwoordigende gasturbiene verbrander aangewend word. Die huidige studie bewys dat hierdie metode die impak/effusie verkoelingsprestasie binne 1% kan voorspel vir 'n eenvoudige geval. Die verbrander gevallestudie bring verskeie 3D effekte wat nie in die lae orde model vasgevang word nie, aan die lig. Die merkwaardigste van hierdie effekte is 'n sterk interaksie tussen die kolkende vlam en die verkoelingsfilm. Hierdie waarnemings verskaf inligting ten einde aanbevelings te maak vir verbeteringe aan die lae orde model. Daar word verder gewys dat die stralings-warmtevloed tot en met 33% van die totale warmtevloed bydrae, en dus is die insluiting van stralingsmodelering in hierdie studie geregverdig. Laastens word 'n sterk sensitiwiteit vir roetneerslag aangedui, wat kan lei tot 'n potensiële verdubbeling van die warmtevloed as gevolg van straling. 'n Verdere ondersoek word benodig om die vlak van roetneerslag op die voering te beraam. So 'n raming sal toelaat dat die emissiwiteit verspreiding van die voering meer betroubaar bereken kan word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/108281
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