Impact of variable geometry combustor on performance and emissions from miniature gas turbine engine

Abstract

The scope of this study is the experimental and theoretical research into the developed concept of variable geometry combustion chamber for miniature gas turbine engine. The aims are to investigate the combustion performance and NOX/CO emissions from combustion chamber and to demonstrate advantages of proposed design over standard, fixed geometry combustor.Experimental studies were performed on a specially designed miniature combustion chamber test stand. Standard GTM-120 combustion chamber and proposed combustion chamber with variable dilution holes area were tested. Pressures and temperatures at main combustion sections as well as NOX and CO concentrations in exhaust gases were measured.Theoretical studies involve numerical simulations of reactive flow inside standard and variable geometry combustion chambers. Detailed chemical kinetic mechanisms were used to describe the chemistry involved in the combustion process. The outputs from numerical simulations are coupled with a reduced system represented by cylindrical share flow reactor model in order to examine the impact of the gas analyzer probe and hose on the composition of the exhaust gases.Results of theoretical studies are in good agreement with results obtained experimentally. Both show significant advantages of utilization of the variable geometry combustion chamber in terms of performance and emissions reduction. The NOX reduction by over 40% in comparison to standard geometry combustion chamber and double reduction in CO emissions for variable geometry combustor were noted. Additionally, the results are compared with real GTM-120 engine performance and emissions from bench testing [3]. Based on the experimental data, a set of 3-D performance and emissions maps has been created. The maps are aimed to aid for variable area dilution zone inside a small gas turbine engine control law creation.