ON SEPARATED SHEAR-LAYER OF BLUNT CIRCULAR-CYLINDER

Separated shear layer of blunt circular cylinder has been experimental ly investigated for the Reynolds numbers (based on the diameter) rangi ng from 2.8 x 10(3) to 1.0 x 10(5), with emphasis on evolution of sepa rated shear layer, its structure and distribution of Reynolds shear st ress and turbulence kinetic energy. The results demonstrate that lamin ar separated shear layer experiences 2 similar to 3 times vortex mergi ng before it reattaches, and turbulence separated shear layer takes 5 similar to 6 times vortex merging. In addition, relationship between d imensionless initial frequencies of K-H instability and Reynolds numbe rs is identified, and reasons for the decay of turbulence kinetic ener gy and Reynolds shear stress in reattachment region are discussed.