Kinetic post-processing of a combustor for helicopters

 

Abstract

simplified kinetics solidThe main objective of this work is to numerically predict the emissions of pollutant species from a combustor for helicopter engines. In particular the attention will be focused on the formation of CO, unburned hydrocarbons and nitrogen oxides (NOx).
The work will be focused on the Rolls-Royce Allison Model 250 Engine, which is a highly successful turbo-shaft engine family, largely studied during previous activities in our group from a fluid dynamic point of view. The engine needs to be further studied to characterize the formation of unburned hydrocarbons, which reduces the combustion efficiency and consequently increase the fuel consumption and NOx.
A kinetic post-processing technique will be adopted, as described in the following. Since NOx are ruled by very slow reactions (if compared to the turbulent mixing times) and affect only marginally the main combustion process, a partial decoupling between chemistry and fluid dynamics is possible. An efficient computational procedure is the so called “kinetic post-processing technique”. In other words, the CFD results (obtained with a simplified kinetic scheme) are post-processed by using a large, detailed kinetic scheme, which is able to accurately predict the formation of NOx. This approach facilitates and makes possible the predictions of NOx and CO formation with detailed chemistry, even in complex geometries. Because of the large number of the cells of the computational grid (about 2 millions), this analysis will take advantage of the parallel version of the kinetic post-processing code.

 

Details

Duration: 10-12 months

Experimental activities: no

Skills: transport phenomena, fundamentals of combustion

People involved: Alessio Frassoldati, Alberto Cuoci

Contacts: Alessio Frassoldati