Mixing of twin swirling helium jets injected from a ramp into a supersonic airstream was experimentally investigated to clarify the interaction between the vortices introduced by the ramp and the swirl. The direction and strength of the swirl were changed by replacing cylindrical chambers through which the injectant was introduced to the injector. The direction of the swirl was either same as or opposite to that of the ramp vortex. Helium concentration distributions were measured in three cross sections. The swirl in the same direction brought the injectant to the center plane of the two jets and merged to a single one, while that in the opposite direction kept each jet apart. However, there was no significant difference in the maximum concentration of helium observed in the tests with different directions and strength of the swirl.
