Compact velocimeter for measurements in highly turbulent flows

Laser anemometry is a technique for measuring local velocities in fluid flows. A compact velocimeter was designed for use in wind tunnels. The optimum optical configuration was chosen according to the nature and concentration of the particles present within the aerodynamic flows. A special beam splitter was devised; calculation of intensity distribution within the measured volume permitted a determination of the maximum dimensions of this volume and their evolution as a function of various parameters. Signal processing is performed by means of spectral analysis. Velocity profiles in a supersonic (Mach 3) mixing zone were determined, as well as the corresponding turbulence profiles; boundary layer probings in transonic flow around an aerofoil showed both the possibilities and the limitations of the method.