Measurements of Fluctuating Pressures on a Circular Cylinder in Subsonic Crossflow

A circular cylinder is tested in crossflow over the subsonic speed range. Time-resolved pressure distributions give information on surface pressure fluctuations; the corresponding drag and base drag coefficients are provided. Measured base pressure fluctuations at low Mach numbers are in agreement with the findings of other researchers. Flowchanges at higher subsonic velocitiesandinto the transonic range are described. Illustrations aredrawnfrom the observations of other researchers, enabling physical explanations to be given to assist toward amoregeneral modeling of theproblem.AtMachnumbersabove0.6 thechangingstrength of the vortices reduces thebase dragcoefficientupto aMachnumber of 0.9, at which the onset of sonicflowincreases the drag. Strouhal numbervariation is compared with the measurements of other authors. The paper concentrates on providing reliable measurements of vortex shedding and base pressure over the subsonic speed range rather than attempting to provide universal correlations.