Incompletely Stirred Reactor Network Modelling for Soot Emissions Prediction in Aero-Engine Combustors
Accepted version
Peer-reviewed
Repository URI
Repository DOI
Change log
Authors
Abstract
The simulation of soot from swirl flames is a problem of relevance for the development of low-emission aero-engine combustors. Apart from detailed CFD approaches, it is of importance to also develop models with modest computational cost so parametric studies can be performed, especially in view of the need to predict engine-out soot particle size distributions to meet future regulations. In this work, the Incompletely Stirred Reactor (ISR) theory is extended to a reactors network formulation, based on the Conditional Moment Closure combustion model. An ISR is a volume V that is inhomogeneous in terms of mixture fraction but is characterised by homogeneous conditional averages, such as temperature and soot mass fraction conditional on the mixture fraction having a particular value. A network of ISRs is then deployed to separately capture soot production and oxidation regions exhibiting different degrees of micro-mixing rates and residence times, as typically observed in rich-burn swirl flames with additional dilution air. The Incompletely Stirred Reactor Network (ISRN) approach is demonstrated on a calculation of the Cambridge Rich-Quench-Lean combustor, where the residence time in the primary and secondary regions are controlled by the relative flow rates in the main annular swirl flow and the downstream dilution jets. The results show that the ISRN approach is computationally efficient and captures the experimentally observed soot tendency trends as a function of the burner operating conditions.