Compressor Exit Conditions and Their Impact on Flame Tube Injector Flows

Abstract

Within a gas turbine engine the flow field issuing from the compression system is nonuniform containing, for example, circumferential and radial variations in the flow field due to wakes from the upstream compressor outlet guide vanes (OGVs). In addition, variations can arise due to the presence of radial load bearing struts within the pre-diffuser. This paper is concerned with the characterization of this nonuniform flow field, prior to the combustion system, and the subsequent effect on the flame tube fuel injector flows and hence combustion processes. A mainly experimental investigation has been undertaken using a fully annular test facility which incorporates a single stage axial flow compressor, diffuser, and flame tube. Measurements have been made of the flow field, and its frequency content, within the dump cavity. Furthermore, the stagnation pressure presented to the core, outer and dome swirler passages of a fuel injector has been obtained for different circumferential positions of the upstream OGV/pre-diffuser assembly. These pressure variations, amounting to as much as 20 percent of the pressure drop across the fuel injector, also affect the flow field immediately downstream of the injector. In addition, general variations in pressure around the fuel injector have also been observed due to, for example, the fuel injector position relative to pre-diffuser exit and the flame tube cowl.