在 25° Ahmed 汽车模型尾部斜面上端布置介质阻挡放电( DBD) 等离子体激励器，通过风洞试验，研究了激励器频率为 9 kHz 时不同激励电压对模型气动阻力系数的影响、10 ～ 25 m /s 风速下的最大减阻率和此时对应的最佳激励电压． PIV 测得的流场图以及PSI 压力扫描系统测得的模型尾部斜面的压力值显示，在 DBD 开启时，激励器周围及尾部斜面近壁面区域流速提高，尾部分离区减小，尾部斜面上测压点处的压力升高; 根据天平传感器测量结果，试验风速为 15 m /s 时获得最大减阻率，为 7． 28% ，对应的最佳激励电压为 18． 5 kV． DBD 激励器通过降低模型的压差阻力起到减阻效果． 随着激励电压的提高，气动阻力系数呈现先下降后趋于平稳的趋势，且存在一个最佳激励电压; 随着风速的增加，需要更高的激励强度才能起到较好的减阻效果．

A dielectric barrier discharge ( DBD) plasma actuator was placed near the flow separation point at the end of the 25° Ahmed automobile model． Through wind tunnel test，the effects of different excitation voltages on the aerodynamic drag coefficient of the model when the excitation frequency was 9 kHz，the maximum drag reduction rate when the wind speed was 10 ～ 25 m /s and the optimum excitation voltage corresponding to this time were stu- died． The flow field map measured by PIV and the pressure value of the tail bevel measured by PSI pressure scan- ning system shows that when DBD is switched on，the flow velocity around the exciter and near the wall surface of the inclined surface is increased，the tail flow separation area is decreased，and the pressure at the pressure mea- surement point on the tail bevel is increased． According to the measurement results of the balance sensor，the maxi- mum drag reduction rate ( 7． 28% ) can be obtained when the experimental wind speed is 15 m /s and the corre- sponding optimal excitation voltage is18． 5 kV． The DBD exciter has an effect of drag reduction by reducing the pressure drag of the model． With the increase of the excitation voltage，the aerodynamic drag coefficient presents a tendency that decreases first and then keeps steady． Therefore，there was an optimum excitation． With the increas- ing wind speed，a higher excitation voltage is required to achieve a better drag reduction effect．