Propagation of Turbulence in Constant-Acceleration Pipe Flow

Abstract

Experimental investigation has been carried out to understand the propagation of turbulence and the related velocity distribution in a constant-acceleration pipe flow. Air is used as the working fluid and the axial velocity of air flow is measured with a hot-wire anemometer. Transition to turbulence is judged on the basis of the history of the axial velocity. Turbulence is generated near the wall in the entrance region and then propagates towards the centerline while traveling in the downward direction. The propagation pattern of turbulence depends on the acceleration. When the acceleration is smaller than a certain critical value, it is similar to that in steady pipe flow. Meanwhile, when the acceleration exceeds the critical value, turbulence propagates to the centerline even near the entrance of the pipe.