Smoke Visualization Over Spinning Cones at Angle of Attack in Axial Flow

Smoke visualizations over spinning cones with various half angles at angles of attack are carried out to study qualitatively the salient features of flows over spin stabilized and axially symmetric bodies. A smoke wire technique is employed while images are captured with a high speed camera. Flow patterns are studied over a range of spinning cones with half angles θc= 10◦,15◦,22.5◦,30◦,45◦,and 90◦. The lengths of the cones are fixed to 20 cm. The rotational speed ratio, S= ΩRbase/U∞, of the cones are fixed to S= 2, where Ω is the rotational speed of the cone,U∞ is the uniform axial flow, and Rbase is the radius of the base of each cone. A range of angles of attack is studied, 0≤α≤36◦. Dictated by the dimensions of the cones, the Reynolds number is on the order of 10^4 for all cases. The potential flow over all nonrotating cones at zero incidence are reviewed for comparison of the flow field inside and outside of the boundary layer. Good agreement between experiment and theory is observed near the tip of the cone at zero incidence for all cases. Signatures of tip vortices are present in the streakline images captured for shallow cones at high angles of attack. In these cases, the influence of rotation on the vortices are observed.