| Drag reduction is very important for supersonic/hypersonic vehicles.Shock wave is a unique aerodynamic phenomenon of supersonic flow field,and the drag caused by shock wave accounts for a large proportion of the total drag of supersonic/hypersonic vehicle.Shock wave drag reduction can significantly improve the performance of supersonic/hypersonic vehicle in many aspects.As a new high-speed jet active flow control technology with no need for air source,plasma synthetic jet actuator(PSJA)has a promising application prospect in supersonic/hypersonic shock wave drag reduction.In this paper,numerical simulation and experiments are combined to improve the performance of PSJA and realize the supersonic/hypersonic shock wave drag reduction based on PSJA as the goal,and researches on opposing PSJA drag reduction characteristics and parameter effect,Laval-shaped/air supply PSJA characteristics and their applications in shock wave drag reduction and wind tunnel experiment verification of hypersonic vehicle standard model shock wave drag reduction based on PSJA are carried out.The flow field characteristics,drag reduction mechanism and parameter effect of single-pulse opposing PSJ in Ma3 supersonic flow field are studied by numerical simulation.Firstly,the numerical simulation results are compared with the wind tunnel experiment results to verify the accuracy of the simulation method.Second,flow field characteristics of opposing PSJ and drag reduction mechanism are studied,the results show that the increase of the standoff distance of bow shock caused by opposing PSJ is the cause of the drag reduction.With the control of opposing PSJ,the bow-shock standoff distance increases first and then returns to the baseline state.Correspondingly,the hemisphere drag decreases first and then returns to the baseline state.Average drag reduction of 9.92% is achieved under typical conditions.Finally,the parameters affecting drag reduction of opposing PSJ are analyzed,and the effects of exit diameter,discharge energy,incoming flow Mach number,incoming flow static pressure and incoming flow angle of attack are studied in detail.The working characteristics of PSJA with a Laval-shaped exit at different dimensionless energy and its drag reduction effect on hemisphere in Ma3 supersonic flow are studied by numerical simulation.Firstly,the numerical simulation results are compared with the schlieren images and pressure measurement results to verify the accuracy of the simulation method.Secondly,the working characteristics of PSJA with a Laval-shaped exit in quiescent air are studied.The results show that when the dimensionless energy is greater than 5.06,the exit velocity of PSJA with a Laval-shaped exit can reach the supersonic level,and the performance is significantly improved.Finally,the drag reduction effect of PSJA with a Laval-shaped exit on hemisphere in Ma3 supersonic flow is studied.The results show that the flow field of a singled-pulsed opposing PSJ can be classified into three patterns according to the value of the dimensionless energy.With the increase of the dimensionless energy,the average drag reduction of PSJA with a Laval-shaped exit increases first and then decreases.The optimal average drag reduction of 25.82% is achieved when the dimensionless energy is48.02,which is about 25.64% higher than that of PSJA with a straight-shaped exit.The working characteristics of PSJA with air supply and its application in supersonic/hypersonic shock wave drag reduction are studied experimentally and numerically.Firstly,the working characteristics of PSJA with air supply in quiescent air are studied.The results show that the jet velocity is significantly improved,and the maximum velocity is up to 830m/s with pressurized cavity pressure of 133 k Pa,which is38% higher than that of PSJA without air supply.The density and temperature characteristics of PSJA are also significantly improved with air supply.Secondly,the control authority of PSJA with air supply on ramp shock waves in high-enthalpy hypersonic flow is studied through wind tunnel experiments.The results show that PSJ can eliminate the shock wave and shock wave intersection point.Finally,numerical simulation is carried out to study the drag reduction characteristics of opposing PSJA with air supply.The results show that the average drag reduction can be further improved by arc discharge when the air supply pressure is high,and the average drag reduction can be improved by about 9.64% when the energy input is 16 J.However,when the air supply pressure is low,the average drag reduction cannot be improved significantly by arc discharge,and the maximum improvement is about 1.84%.A wind tunnel experiment is carried out to study the control effect of PSJA on bow shock wave and flank shock wave of a hypersonic vehicle standard model.The highspeed schlieren results show that the bow shock wave is significantly pushed away and the flank shock waves are eliminated.The variation of total drag of the vehicle under the control of PSJ is measured by dynamic force sensor,and the results show that the drag decreases to some extent.The pressure change of the vehicle surface under the control of PSJ is measured by pressure sensitive paint technology,and the results show that the pressure decrease to a certain extent,but the influence of discharge arc light and discharge products on the measurement results needs further analysis. |
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