This research focused on furthering the current understanding of the flowfield inside a cavity under typical flight conditions. The flight envelope included altitudes of up to 40,000 ft and maximum Mach number of 1.28 and included several test points between Mach 0.9 and 1.1, which are challenging to isolate in wind tunnel testing due to tunnel wall interference. The pod was instrumented to collect aeroacoustic pressures and qualitative flowfield imaging for a cavity with a length-to-depth ratio of four. Test missions were flown with several different passive flow control configurations, and their respective effect on acoustic properties and flow patterns were collected. Flow control comprising a rod-in-a-crossflow or a traditional sawtooth spoiler was generally found to reduce sound pressure level, though the extent of effectiveness varied with flight condition. The flow control devices installed at or below the cavity exit plane were found to have little influence. Tuft-based flow visualization complemented the effort, for one example, by demonstrating the outward flow near the cavity lip for the sawtooth spoiler.

这项研究的重点是进一步了解当前在典型飞行条件下腔体内流场的理解。飞行包线包括高达40,000英尺的高度和最大马赫数为1.28，并包括0.9至1.1马赫数的多个测试点，由于风洞壁的干扰，很难在风洞测试中进行隔离。该吊舱经仪器采集，以收集空气声压和定性的流场成像，该腔的长深比为4。使用几种不同的被动流量控制配置执行测试任务，并收集它们各自对声学特性和流动模式的影响。人们普遍发现，包括横流杆或传统的锯齿扰流板在内的流量控制可降低声压级，尽管效果的程度随飞行条件而变化。发现安装在型腔出口平面处或下方的流量控制装置几乎没有影响。基于簇绒的流动可视化补充了这一努力，例如，通过展示锯齿扰流器腔唇附近的向外流动。