Helicopter drag reduction by vortex generators

The performance of vortex generators in reducing the helicopter drag was investigated by computational fluid dynamics and wind tunnel tests. Numerical simulations were carried out to define the layout and the position of vortex generators to be tested on a heavy-class helicopter fuselage model. A comprehensive experimental campaign including loads, pressure measurements and stereo particle image velocimetry surveys was then performed to assess the results of the numerical activity. Experiments confirmed the main trends predicted by computations. Tests for an array of vortex generators positioned on the model back-ramp showed a maximum drag reduction of about 5% with respect to the clean geometry. Moreover, the analysis of the velocity field and of the pressure distribution around the backdoor/tail-boom junction enabled to investigate the flow physics related to the effect of vortex generators on the fuselage drag.