Novel lift enhancement method based on zero-mass-flux jets and its adaptive controlling laws design

For lessening the weight and volume of flow control system, enlarging the circulation control applying area of angle of attack (AOA), and achieving nice controlling characteristics, a novel lift enhancement method based on dual synthetic jet actuators (DSJAs) and synthetic jet actuator (SJA), and an adaptive proportional integral and differential (PID) algorithm based on radial basis function neural network are introduced. DSJAs are uniformly located along the chord to suppress the separation and trailing-edge SJA is applied to achieve the high circulation. Velocities of actuators are modulated to realize the real speed profile and on–off controlling laws of DSJAs are designed. Numerical simulations show that DSJAs and SJA could suppress the separation completely and move leading-edge stagnation point and trailing-edge separation point downstream even at AOA of 19°, hence achieve the highest lift and nose-down moment augmentation (Δ Cl_max= 0.92, Δ Cm_max= 0.02534), and Δ L/ D can reach 11.39 at AOA of 18°. Stalling is delayed to more than 19°. Linear lift area and pitch-break angle are both increased to 16°. Δ Cl/ C_μ can reach 76.7, indicating the greatest control efficiency. The results of adaptive PID control, whose controlling effects are proved better than PID, indicate that lift could track the objective with the rise time of 0.0325 s and finally keep steady, suggesting the nice stability and rapidness. Graphic abstract: [Figure not available: see fulltext.]