Vortex ingestion in a diffusing S-duct inlet

Abstract

An experimental study of the effects of an ingested vortex on the flowfield of a diffusing S-duct inlet model is reported. Three test conditions vary by the location of where the vortex enters the model. For each test condition two different S-duct configurations are examined, a baseline S-duct and an S-duct with an array of surface-mounted vortex generators. The data taken consist of duct inlet and exit crossplane surveys of velocity and total pressure and surface flow visualization. The data are compared to identical S-duct data taken in the absence of an ingested vortex. The ingested vortex is observed to have a strong influence on the S-duct flowfield, but only when the vortex trajectory is near the region of flow separation that exists in the baseline S-duct. The ingested vortex at this location reduces the extent of flowfield separation inside the baseline duct and promotes stronger crossflow of both the baseline duct and the duct with vortex generators. This enhanced crossflow also strengthens the vortices shed from the vortex generators. The other ingested vortex locations are found to produce little effect on the flowfield of the duct, with or without vortex generators.