Study of a confined turbulent jet: influence of combustion and pressure on the flow

Authors: Duwig, C., Fuchs, L.F., Griebel, P., Siewert, P., Boschek, E.
Document Type: Article
Pubstate: Published
Journal: AIAA Journal
Volume: 45   624-639
Year: 2007


Today, environmental issues play an important role in the viability of modern low-emission power plants. As a consequence, gas turbine combustors need to be operated at lean premixed conditions. However, successful designs require a detailed knowledge of the combustion process under realistic operating conditions. The present study focuses on nonreacting and reacting jets at operating pressures from 1 to 14 bar. First, an isothermal confined jet has been studied experimentally and numerically using particle image velocimetry and large eddy simulation. The flow is highly turbulent and includes large-scale unsteady structures. The comparison of the numerical results and the experimental velocity data showed an excellent agreement that was generally below the numerical or experimental uncertainty. Second, the influences of combustion and operating pressure on the flowfield were investigated. The large eddy simulation results showed that the jet core was lengthened, due to the density jump across the flame. The effect of pressure on the flame was studied using planar laser-induced fluorescence and large eddy simulation at a constant Mach number. The flame brush and the velocity fields were found to be relatively insensitive to an increase of pressure from 1 to 14 bar (and, correspondingly, to an increase of Reynolds and Karlovitz numbers). The numerical results suggest that increasing pressure decreases the laminar flame speed and increases the flame-front wrinkling, causing the turbulent flame speed to be less sensitive to pressure.