12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Turbine subsystem cooling design depends on the profile of the non-dimensional temperature dis-tribution function (TDF), measured at a traverse plane upstream of the nozzle guide vane (NGV). To date, the compressor discharge OGV profile was thought to have an insignificant effect on the resulting combustor exit traverse, hence a generic OGV geometry has been used for such tests, which typically remained unchanged between varying combustor designs. The present study how-ever shows that the wake profile of the OGV has a significant influence on the measured combustor exit traverse profile. Experiments were performed at Loughborough University with varying OGV geometries to simulate the aerodynamic field surrounding the combustor. Corresponding numer-ical analyses were performed using an in-house combustion analysis code with a passive scalar technique to model the CO2 tracer gas injection and mixing. Analysis of the experimental and nu-merical simulations confirm that the pressure and velocity profiles presented to the system by an axial flow compressor influence both the mass flow and pressure distributions within the combus-tor feed annuli. This in turn affects the ratio of the mass flow rates entering the flame tube through the dilutions ports located around the inner and outer annuli. The flow through these ports con-trols the bulk mixing within the flame tube, resulting in a change in mixture concentration profile measured near the combustor exit. Hence, reproducing engine-representative OGV wake struc-tures for a given engine together with an accurate representation of the combustor configuration is of key importance to reproducing the temperature profiles that inform turbine cooling design.