Characteristics of compressible rectangular cavity flows

Experiments are performed to study the effect of cavity geometry and Mach number on the characteristics of compressible rectangular cavity flows. The study indicates that the corresponding length-to-depth ratio for the open- and transitional-type cavities increases with higher freestream Mach number. The depth-to-incoming boundary-layer thickness ratio is another important parameter to define the type of the cavity flow. The upstream influence region is minimized with the presence of a cavity, and larger downstream influence region is observed for the transitional-closed- and closed-type cavities. The distributions of surface pressure fluctuations show similar trend as those of static pressure distributions. The amplitude of surface pressure fluctuations increases toward the rear face for an open-type cavity, whereas a minor peak near the middle of the cavity floor is observed for a closed-type cavity. A transitional-type cavity induces more intense surface pressure fluctuations at the cavity floor. Higher levels of pressure fluctuations near the rear face are observed at higher Mach numbers for the transitional- and open-type cavities.