合成射流对类车体流动控制的影响

Influences of a Synthetic Jet Actuator on the Flow Around Ahmed Body

摘要:

基于大涡模拟对有无合成射流控制的三维类车体流场进行仿真，与试验结果对比，验证仿真方法有效.平均场结果表明，当合成射流出口位于顶盖和斜背交界处时，可减弱流动分离, 缩小回流区, 改变背压，降低阻力.频谱分析显示，当激励动量系数超过1.0×10-4时，斜背表面压力、回流区速度和涡量以及阻力系数功率谱密度对应的峰值频率皆为激励频率.瞬态流场分析结果指出，合成射流与外流之间的交互作用导致了阻力系数曲线中出现周期性改变的波谷和波峰.

关键词:大涡模拟; 类车体; 合成射流; 气动减阻

Abstract:

Largeeddy simulation (LES) was used to study the unsteady flow around Ahmed body in both natural and controlled flow. The simulation results were validated against the experimental data. The meantime results indicated that flow separation could be suppressed when a synthetic jet actuator was located at the junction of the roof and the slant, which could result in a smaller separation zone and aerodynamic drag reduction. Spectrum analyses revealed that with the momentum coefficient of excitation is more than 1.0×10-4，the peak frequency of power spectral density surface pressure on the slant，velocity and vortices in the recirculation zone, as well as drag coefficient is related to driving frequency. The transient flow results suggest that the interaction between the jet and the flow lead to periodical changes of the peak and trough of drag coefficient.

Key words:largeeddy simulation; Ahmed body; synthetic jet; aerodynamic drag reduction