Experimental and Numerical Analysis of Turbulent Air Flow Around a Surface Mounted Hemisphere


Department of Mechanical Engineering,Shiraz University


The air
ow field around a surface mounted hemisphere for different velocities is
investigated experimentally and numerically. Hot-film anemometry is used in a wind tunnel to analyze
ow structure for different regions of
ow domain around the hemisphere. The
ow Reynolds number
is varied based on the hemisphere diameter and free stream velocities. The air velocity is taken as 5, 7
and 8.5 m/s, with corresponding Reynolds numbers of 35000, 50000 and 64000. To illustrate the
pattern around the hemisphere, variations of
ow velocity at various vertical sections along the midplane,
and cross-stream velocities for various surfaces and heights, are measured and plotted. Corresponding
numerical solutions are also carried out to visualize the
ow reversal, horseshoe vortices and recirculation
zones around and downstream of the hemisphere. It is concluded that the
ow is highly Reynolds number
dependent, especially at the reversed
ow region upstream and downstream of the hemisphere. Moreover,
the e ect of hemisphere location in the tunnel is studied, and velocity distributions are compared and
presented in the wake of the hemisphere for constant free stream velocity.