Experiments were conducted at freestream Mach numbers of 0.55, 0.80, and 0.90 in open cavity flows having a length-to-depth ratio L/D of 5 and an incoming turbulent boundary having a thickness of about 0.5Z). To ascertain aspect ratio effects, the length-to-width ratio L/W was varied between 1.00, 1.67, and 5.00. Two stereoscopic PIV systems were used simultaneously to characterize the flow in the plane at the spanwise center of the cavity. For each aspect ratio, trends in the mean and turbulence fields were identified, regardless of Mach number. The recirculation region had the weakest reverse velocities in the L/W = 1.67 cavity, a trend previously observed at supersonic Mach numbers. Also, like the previous supersonic experiments, the L/W = 1.00 and L/W = 5.00 mean streamwise velocities were similar. The L/W = 1.00 cavity flows had the highest turbulence intensities, whereas the two narrower cavities exhibited lower turbulence intensities of a comparable level. This is in contrast to previous supersonic experiments, which showed the lowest turbulence levels in the LIW= 1.67 cavity.
展开▼
机译：在自由流马赫数为0.55、0.80和0.90的开放腔流中进行实验，该流的长深比L / D为5，进入的湍流边界厚度约为0.5Z。为了确定纵横比的效果，长宽比L / W在1.00、1.67和5.00之间变化。同时使用两个立体PIV系统来表征腔体翼展方向中心平面中的流动。对于每个纵横比，无论马赫数如何，都可以确定平均和湍流场中的趋势。在L / W = 1.67腔中，回流区域的反向速度最弱，这是先前在超音速马赫数下观察到的趋势。同样，像以前的超音速实验一样，L / W = 1.00和L / W = 5.00的平均流向速度相似。 L / W = 1.00的空腔流动具有最高的湍流强度，而两个较窄的空腔显示出较低的湍流强度，具有可比的水平。这与先前的超音速实验相反，后者在LIW = 1.67腔中显示出最低的湍流水平。
展开▼
