| In the field of aviation,the energy consumption of the aircraft is mainly used to overcome the drag force in flight.For subsonic aircraft,the viscous drag accounts for 40%-50%of the total drag,and the turbulent friction drag is the main component of the surface viscous drag.Therefore,reducing the turbulent friction drag is crucial to minimize aviation’s energy consumption and carbon emissions.Plasma flow control technology is one of the means to achieve turbulent boundary layer drag reduction,with the advantages of fast response,no moving parts,and a wide actuation band.An improvement on the classic Dielectric Barrier Discharge(DBD)plasma actuator,the Trielectrode Dielectric Barrier Discharge(TED)plasma actuator boasts the benefits of controllable jet direction and a more significant jet velocity.This thesis will conduct experimental and simulation studies on the aerodynamic characteristics of the TED actuator.It aims to apply these characteristics to turbulent flow control and investigate the effects of different discharge modes of the TED on the control of the turbulent boundary layer.The research content of this paper includes the following three aspects:(1)To study the electrical,flow field,and body force characteristics of different discharge modes(DBD,EX-DBD,and SL-DBD).Based on the electrical parameter measurement system,the PIV(Particle Image Velocimetry)technique and the differential calculation of the body force,the actuator power consumption,the maximum induced jet velocity,and the body force combined force are obtained.Based on the above multiple dimensions,the quantitative parameters of the actuator flow control performance are calculated.It is found that the combined volumetric force of EX-DBD and SL-DBD improves by 91.15%and 141.33%,respectively,compared with DBD;the overall flow control performance of EX-DBD and SL-DBD is 3.63 times and 3.88 times that of DBD.(2)Based on the PASSKEY(Parallel Streamer Solver with Kinetics)simulation platform to solve the two-dimensional fluid model,the spatial and temporal distributions of charge,various particles,and electric field for different discharge modes of the three-electrode plasma actuator are obtained.Further,the body force distribution under different operating conditions of the actuator is obtained by body force approximation.The periodic evolution law of the body force is calculated to obtain the contribution of positive and negative charges to the body force.The simulation results find that the residual charge generated by the DC electrode is not negligible and leads to the generation of EX-DBD and SL-DBD flow injection about 0.1μs earlier than DBD;the generation of flow injection leads to the space charge surge is the main reason for the increase of the body force.(3)The control effects of three discharge modes of the three-electrode plasma actuator on the turbulent boundary layer are investigated separately in the low-speed turbulent wind tunnel.The experimental results found a positive correlation between the pulse frequency and the drag reduction rate,and the highest drag reduction rate of DBD reaches 6.8%when the actuation frequency increases to 200 Hz.The drag reduction effect of EX-DBD has no significant change compared with DBD;under the optimal working condition,the drag reduction rate of SL-DBD increases by 3%compared with DBD,and the angle between the induced jet and the wall is 120.3°.This flow control is similar to slit blowing,which can effectively suppress the upward and downward sweeping motion and break the regenerative cycle of the wall strip structure,thus achieving a higher drag reduction effect. |
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