Abstract: An on-axis 2-D LDV system for measuring two velocity components in the plane formed by three incident beams was presented. The measuring errors in on-axis direction were discussed and a method for correcting the angular deviation was suggested. Detailed measurements were made in a pipe flow for single and double orifice cases by using: this system. Mean velocity, turbulent intensity and Reynolds shear stress distributions in axial and radial directions were measured at the Reynolds number of 1.4×105.Compari...