Experimental Investigation of Air Flow Velocity Distribution and its Turbulences in an Octagonal to Square Diffuser.

An octagonal to square diffuser is an important section of the vertical wind tunnel, which has been designed for sky-diving operations. To determine the actual pressure drop of the diffuser, the velocity distribution should be measured. In addition, flow separation can be investigated by velocity distribution. In this research, a 7.8 % model of the original diffuser has been constructed, and velocity distribution and turbulence intensity of airflow have been measured using hot-wire Anemometer. The results of velocity distribution and turbulence intensity showed no flow separation in the tested diffuser. The error associated with pressure drop estimation is significant in the absence of the velocity distribution effects.