Replacing the Aileron of the High-Lift Common Research Model with Trailing-Edge Coanda Actuators

The aileron control surface of the High-Lift Common Research Model (CRM-HL) is replaced with a segment of trailing-edge Coanda actuators to increase the takeoff lift-to-drag ratio without employing any external moving parts. The 10% scale CRM-HL model is simulated with computational fluid dynamics at takeoff conditions with the aileron at four deflection angles. A wide variety of trailing-edge Coanda actuator designs are tested in two-dimensional simulations for identifying the dominant geometric variables of the active flow control (AFC) technique. These variables include airfoil truncation, blowing direction, Coanda surface shape and size, and slot height. The optimal Coanda surface design, equipped with upper and lower slots, is installed on the CRM-HL model for simulations at takeoff conditions. Without blowing applied, the Coanda flow control design increases takeoff drag by 12 counts. At a fixed takeoff angle of attack, the Coanda actuators increase lift by 10.5%. At a fixed takeoff lift coefficient, the Coanda actuators increase the L/D by 2.5%. Throughout the study, results are compared to simulations and experiments of an AFC-augmented aileron on the CRM-HL.