A CFD-CSD coupled-analysis of HART-II rotor vibration reduction using gurney flaps

A dynamically deployed Gurney flap was examined as an active control device for rotor vibration reduction. A CFD-CSD coupled analysis was carried out to include the aeroelastic effects and to maintain trimmed state. The four-bladed HART-II model was used as a representative rotor. A modeling method for dynamically deployed Gurney flap was established using dynamic wall boundary condition and infinitely thin flap model. 2-D analyses were performed to investigate the unsteady air load response to the Gurney flap deployment, specifically the time lag effects, and the initial flap deployment schedules were established. The four-per-revolution deployments of the Gurney flap on lower and upper surfaces were simulated and the resulting vertical vibratory loads were compared with the baseline rotor. The simulations indicate that an 83% reduction of the four-per-rev vibratory load may be achieved while maintaining the trim state without significant performance penalty. It was also shown that the four-per-revolution vibratory load may also be virtually eliminated using an optimized deployment of the Gurney flap. Potential of individual control of segmented Gurney flaps targeting multiple signals was also demonstrated by suppressing eight-per-rev components of vibratory loads while minimizing four-per-rev vertical load simultaneously.