Tail rotor aerodynamic performance improvement with a Gurney flap design

Abstract

As per of the effort to increase maximum take-off weight (MTOW) of an indigenous unmanned rotorcraft, increase in tail rotor thrust to compensate resulting higher main rotor torque values is required. Current study summarizes design and analysis of a gurney flap configuration utilized for the present tail rotor of the UAV. Computational fluid dynamics (CFD) analyses are performed for two dimensional airfoil (included Gurney flap) solution with commercial tools. Rotor mathematical model developed with FlightLab operates the generated aerodynamic database of the blade profiles to evaluate rotor total performance improvement. Several Gurney flap designs are constructed on the present blade profiles and configuration that optimizes tail rotor aerodynamic performance according to the desired aspects is evaluated with higher fidelity three dimensional CFD analysis methods. It is evaluated that the designed Gurney flap dimensions are such small that production and assembly may have direct impact on the total performance improvements. Therefore, the geometry of the desired Gurney flap is modified according to the possible manufacturing tolerances and assembly defects and analyses are repeated to investigate the efficiency degradation between analytical design and the product. Current study presents the gurney flap design as well as aerodynamic performance improvements of profile and rotor for both theoretical design and possible product.