开口射流风洞主动湍流产生过程中动态射流特性

Dynamic Jet Behavior During Active Turbulence Generation in Open Jet Wind Tunnels

出于可重复性考虑,车辆空气动力学和气动声学的研发工作主要在风洞中稳态流动条件下进行,然而在真实路况下车辆经受着非稳态湍流,这是由比如侧风阵风、路边障碍物与稳定侧风的组合影响或前方行驶的车辆所引起的.为了能够以可重复再现的方式来模拟该路面场景,开发了一套主动湍流发生器系统FKFS swing?,并运用于斯图加特大学的全尺寸气动声学风洞中,风洞由FKFS运营.该系统由垂直跨越风洞喷口的8个翼型组成,能够以高达10 Hz的频率动态改变流动角度.先前的研究表明,开口射流对主动偏转的动态响应改变了由位置和频率变化所产生的流动角度.一种用于量化该特性的方法被提出并运用于斯特劳哈尔数高达0.45的情况.本研究中,该方法被用于分析更高斯特劳哈尔数至1.2情况下的动态响应,这与非稳态气动声学相关.结果表明,在更高的斯特劳哈尔数下射流特性对流动角度的影响减小.

The aerodynamic and aeroacoustic development of vehicles is,for reasons of reproducibility, mainly done in wind tunnels under steady flow conditions. In a real situation on road, however, a vehicle experiences unsteady, turbulent flow. This results for example from side wind gusts,obstacles at the roadside in combination with steady side wind,or vehicles driving;in front. To be able to simulate the on-road scenario in a reproducible manner the active turbulence generation system FKFS sswwiinngg? has been developed and implemented in the full-scale aeroacoustic wind tunnel of the University of Stuttgart,which is operated by FKFS. It consists of eight airfoils vertically spanning the nozzle. It allows to dynamically vary the flow angle by frequencies of up to 10 Hz. Previous research has already shown a dynamic response of an open jet to active deflection, which alters the resulting flow angle depending on location and frequency. An approach to quantify the behavior was presented and was applied for aerodynamically relevant Strouhal numbers of up to 0.45. In this study, the approach is applied to analyze the dynamic response for higher Strouhal numbers of up to 1.2,which are relevant for unsteady aeroacoustics. The results show a decreasing effect of the jet behavior on the flow angle at higher Strouhal numbers.