Study On The Performance Of Helicopter Rotors With Gurney Flaps

To investigate helicopter performance with the rotor deployed with Gurney flaps, a helicopter flight dynamics model is coupled with a Gurney flap model to analyze the fight performance. The flight test data of UH-60 A helicopter is utilized to validate the modeling. The influence of helicopter weight coefficient, Gurney flap height, deployment position and type on the rotor power is investigated. The distribution of the angle of attack over the rotor disk, rotor pitch controls and fuselage attitude angles are also analyzed. The results indicate that the Gurney flap can significantly reduce the required rotor power with larger takeoff gross weight at higher speed forward flight. The movable Gurney flap can achieve better performance improvement than the fixed height Gurney flap. The power reduction increases with the height of Gurney flap and then decreases. The Gurney flap can introduce a larger power reduction when the position of Gurney flap is near the blade tip. The deployment of Gurney flap can distinctly decrease the maximum angle of attack in the retreating side with larger takeoff gross weight at higher speed forward flight. The collective, longitudinal and lateral cyclic pitches decrease with the deployment of Gurney flaps. The deployment angle of gurney flap is designed to change with azimuth to improve helicopter performance. The variation in sine type can obtain more power savings than other schedules studied. The second and third harmonic inputs of the Gurney flap to reduce rotor power are investigated, and the analyses indicate that the higher harmonic inputs can decrease the rotor power required.