Measurements, visualization and interpretation of 3-D flows: application within base flows

Experimental investigations of the flow field in the near-wake of axisymmetric afterbodies at an angle of attack of 5° are presented. Models consist of a cylindrical afterbody and a conical boat-tail. Measurements were performed by means of a three-dimensional (3-D) frequency-shifted laser Doppler velocimeter at a freestream Mach number of 0.5. Results include wall static pressure distributions over the afterbody and on the base, mean velocities, and the corresponding velocity fluctuations. The results show that a 3-D laser Doppler velocimeter is a useful tool to provide well-documented information of complex flow fields of an axisymmetric or 3-D nature for confrontation between theory and experience. Several approaches to the display and interpretation of the large amount of data obtained when investigating flows of 3-D nature, are presented. A fast and efficient algorithm for the visualization of 3-D scalar data fields is presented. It can realistically reconstruct and display contour surfaces