This first part of the paper presents techniques implemented for the experimental investigation of the transition mechanism in 2-D pressure driven separated boundary layer flows over a flat plate at inlet free-stream turbulence intensities ranging from 0.3 to 0.6% and imposed adverse pressure gradients ranging from K = − 0.68 × 10−6 to − 6.25 × 10−6. The structure and behavior of the separation bubble were investigated for various flow conditions. The separated-flow transition modes were identified and classified. The distribution end strength of the adverse pressure gradient were obtained by varying the test section outer wall divergence angle.
Specific methods identifying the main parameters that characterize separated-flow transition are introduced and issues regarding measurements of reverse flow are discussed. The methods implemented in determining the separation point, maximum displacement location, the unsteady reattachment region, the start and end of transition, etc. are described.