A low-speed wind-tunnel study of the flow about a 76/40-deg double-delta wing is described for angles of attack ranging from -10 to 25 deg and Reynolds numbers ranging from 0.5 to 1.5 Million. The study was conducted to provide data for the purpose of understanding the vortical flow behavior and for validating Computational Fluid Dynamics methods. Flow visualization tests have provided insight into the effect of the angle of attack and Reynolds number of the vortex-dominated flow both on and off of the surface of the double-delta wing. Upper surface pressure recordings from pressure orifices and Pressure Sensitive Paint have provided data on the pressures induced by the vortices. Flowfield surveys were carried out at an angle of attack of 10 deg by using a thin 5-hole probe. Numerical solutions of the compressible thin-layer Navier-Stokes equations were conducted and compared to the experimental data. Verhaagen, N. G. and Jenkins, L. N. and Kern, S. B. and Washburn, A. E. Langley Research Center NAS1-19480; RTOP 505-90-52-01...

A wind-tunnel investigation was performed to study, by employing a laserlight-sheet and oil-flow visualization technique, the flow above and behind a sharp-edge 76 deg, delta wing and two sharp-edged double-delta wing models (76/60 and 76/40 deg., kink at midcord). In addition, balance measurements were performed to determine lift, drag and pitching moment. The tests were carried out for angles of attack from 5 to 25 deg. and at a free-stream velocity of 30 m/sec, corresponding to a Reynolds number of 1400000 x 10 to the 6th power, based on centerline chord. Above both double-delta wings a single-branched strake vortex is formed fed by vorticity from the strake leading edge. Downstream of the leading-edge kink a wing vortex is formed which is conjectured to be single-branched at about 5 deg, angle of attack and double branched at angles of 10 deg., an beyond. The flow pattern downstream of the trailing edge of the 76/60 deg. double-delta wing has been observed to be similar to that behind the delta wing. Above the 76/40 deg. double-delta wing breakdown of both the wing and strake vortices took place ahead of the trailing edge. (Author).

A family of double-delta wings with leading-edge sweep combinations of 80/80,80/7080/6080/50 and 80/40 deg. was tested in a small towing tank. The hydrogen bubble technique was used to visualize the vortex patterns above the wings over a range of Reynolds numbers (based on centerline chord) from 7000 to 100,000. The effects of variations in incidence and leading-edge kink angle were examined. Reynolds number and leading-edge cross-section shape were found to have significant effects on the vortex structure. Attempts to visualize details of the upper surface secondary vortex flows met with only partial success. Keywords Flow visualization, Vortices, Delta wings, Angle of incidence. (Australia).