Research On Aerodynamic Characteristics And Mechanism Of Circulation Control Wing

As an efficient active flow control technology,the circulation control has great potential for aerodynamic improvement and performance enhancement of aircraft.In view of the limitations of conventional wing on aerodynamic lift and the deficiencies in rudder effect control,the increase of weight and the complicated maintenance,in this paper,the circulation control technology is used as a means to verify its aerodynamic increasing and control effect on the aircraft,combined with the flow display experiment,analyzing the flow mechanism of aerodynamic increase and control.First of all,the numerical control was used to select the parameters of the circulation control airfoil trailing edge,and the H/Rcc=0.067 of the two-dimensional circulation increasing airfoil was selected as the design parameter.At the same time,analyzing the aerodynamic characteristics of the multistage circulation control airfoil.Based on the single slot circulation control airfoil,according to the flow separation point of the trailing edge,the second slot and the third slot are added,and the step-up blowing method is used to verify the multi-slot circulation control airfoil lifting effect.The numerical simulation results show that the maximum lift-to-drag ratio of the single slot circulation control airfoil is 41.9,the double slot is 62.3,and the treble slot reach 83.3.at the same time,the paper introduces the concept of“effective lift-to-drag ratio”and analyzes the blowing efficiency of multi-slot circulation control airfoil and circulation control wing.The results show that when the blowing coefficient is 0.013,the blowing efficiency of single slot circulation control airfoil is the highest,the effective lift-to-drag ratio is 35;the maximum effective lift-to-drag ratio of the double slot is40.65;the maximum effective lift-to-drag ratio of the treble slot is 48.9.Based on the above numerical simulation results,the H/Rcc=0.067 of the circulation control device is selected as the design parameter,designing a set of circulation control device that can blow up and down,and appling to the aircraft for aerodynamic forces and pneumatic torque control.Next,analyzing the aerodynamic force and moment of the same size conventional rudder model and the circulation control model by wind tunnel experiment.It is found that,at the same angle of attacking,compared with the conventional aileron with deflection angle of 30°,the circulation control wing with blowing Coefficient is 0.04,the stall angle of attack increases by 35.7%,the lift coefficient increases by 32.4%and the roll moment coefficient increases by 60.3%.Using the concept of effective lift-to-drag to analyze the blowing efficiency of the circulation control wing,the results show that when C_?=0.02,the circulation control wing has the highest blowing efficiency,and the maximum effective lift-to-drag ratio is 9.3.At the same time,the rolling moment control effect produced by the loop control wing is better than that of the conventional rudder in the entire range of angle of attack;When C_?=0.04,the rolling torque is increased by a maximum of 95%compared with the conventional rudder surface declination of 30°.When the upper and lower sides of the circulation control device are blowing at the same time,the yaw moment can be generated.As the angle of attack increases,the incremental value of the yaw moment under different blowing coefficients increases.Each increment of the blowing coefficient increases by 0.01,and the increment of the yaw moment coefficient increases by 0.075.Finally,the particle image velocimetry(PIV) is used to study the flowing field of the circulation control model,and analyzing the flow mechanism of the causes of aerodynamic force and moment.The reason for the aerodynamic characteristics of the wing improved by the circulation control device is the low energy fluid in the boundary layer of the trailing edge is reduced under blowing condition,the streamwise momentum increases,the ability of resisting adverse pressure gradient is strengthened,so that the separation flow is suppressed.At the same time,the higher velocity jet deflects the airflow at the trailing edge,increases the amount of circulation,changes the lift of the airfoil.In addition,circulation control device designed in this paper can generate the rolling torque required for aircraft flight control,and the control efficiency is higher than the aileron.When the circulation control device blows air up and down,the yaw moment can be changed,which has the potential to replace the rudder.