The Distortion of a Jet by Coil Inserts

Abstract

Results of experimental investigations of the effects of distortion caused by coil inserts on a turbulent jet are presented. The coils have different wire diameters with constant pitch spacing. The ratios of the coil wire diameter to the tube inside diameter, d/D, are 0.06, 0.08, 0.11, 0.13, and 0.16 and the ratio of the pitch spacing to the tube inside diameter, p/D, is 1.2. Results show that the coil inserts enhance the mixing process. At the jet-outlet, mixing enhancement is increased when d/D<0.1. However, further downstream, the highest mixing is achieved for the coil with the largest d/D ratio. Results suggest that the streamwise vortices generated by the coil inserts are the mechanism behind the high entrainments and the mixing process.