The effect of a fillet on a wing/body junction flow

Abstract

Time-averaged properties of a wing-body-junction flow surrounding a cylindrical wing with a 1.5:1 elliptical nose and a NACA 0020 tail have been compared to those for the above wing with a 1.5 inch radius fillet normal to the wing's surface. An attempt was made to determine the effectiveness of the fillet in improving the uniformity of the wing-body junction flow downstream of the wing, and in attenuating the junction vortex. Measurements included oil-flow visualizations and surface-static-pressure measurements of the flattest floor surrounding the wings, and hot-wire anemometer measurements made in the flow downstream of the wing. Calculations of the drag and the volumetric entrainment of free-stream fluid due to the presence of the baseline wing and wing with fillet were performed. The results of these calculations are important criteria used to determine the effectiveness of the fillet as a flow control device.

Results show that the vortex is present in each case, and its size is slightly larger for the wing with fillet as compared to the baseline wing. For each test case, the drag and volumetric entrainment of free-stream fluid were the nearly same for the wing with fillet as compared to the baseline wing. It was also found that increases in the boundary-layer thickness cause only small increases in the size of the junction vortex. The 1.5 inch radius fillet does not appear to be a viable flow control device.