The characteristics of Coanda effect on the thin curved wall jet issued from a narrow annular exit (named "Coanda jet") are investigated. The characteristics of coaxial jet formed by the interaction of a thin annular jet guided by a half spherical surface and a round jet ejected from the center of the half sphere are also investigated.
Mean velocity, turbulence intensities and Reynolds shear stress are measured with a linearized 2-channel constant temperature hot wire anemometer with varying initial conditions-exit velocity and nozzle gap.
Axial mean velocity profile attains self-similarity after axial distance of about 2.5 Do for both the Coanda jet and the coaxial jet. Centerline velocity decays at a rate of (X-Xo)$^{-1}$ downstream for the Coanda jet and (X-Xo)$^{-0.65}$ for the coaxial jet.
For the Coanda jet flow, half-jet width is reduced first due to the deflection of jet by Coanda effect and becomes minimum at about X=1.5 Do and then grows according to a linear relation, 0.1 (X-Xo). For the coaxial jet, the spreading rate of half-jet width downstream is about 0.11-0.12 which is larger than 0.0848 for the case of conventional round jet.
Velocity fluctuations do not attain complete similarity until about X=9 Do, however the profiles are almost of the same shape as those of conventional round jet but with lower values.
