This paper deals with an experimental study of detailed process of bypass transition and transition originating from separation on low pressure turbine airfoils of aero engines. In this experiment, PIV (Particle Image Velocimetry) measurements are performed on the suction side of low-pressure linear turbine blades at three Reynolds numbers and four levels of freestream turbulence conditions. On PIV measurements, seeding particles are inserted into the wind tunnel, and their motions are captured by high speed camera over the suction surface. In this experiment, we investigate more quantitative results by calculation of vorticity and velocity fluctuation vectors.