LASER VELOCIMETER MEASUREMENTS AND CAVITATION OBSERVATIONS ON TWO AXISYMMETRIC BODIES

Flow measurements on a longitudinal blunt circular cylinder and on an ogive with a groove are reported. Profiles of the axial and radial mean velocity components and RMS values of the two fluctuating components were obtained, and spectrum analysis of the fluctuating signals was performed. It was found that when transition occurs the velocity level is increasing linearly with a decrease in the frequency on a log-log plot of the power spectrum at which point the ratio of low-pass filtered to high-pass filtered RMS value is a maximum. Cavitation observations confirmed that inception often occurs in the neighbourhood of the low-pressure centres of vortex cores both in the shear layer of the blunt cylinder and in the groove on the ogive.