Experimental study of the flow field downstream of a single tube row

Abstract

This report describes the investigation of the flow phenomena at various positions downstream of a tube row having a pitch-to-diameter ratio of 1.3, using a Pitot tube, a Kiel probe, and a hot-wire anemometer. The flow through this row of parallel cylinders can be considered as a number of two-dimensional jets passing through the gaps of the cylinders. The experimental results show that the flow is unstable at these conditions. The instability results in the jets tending to coalesce in random groups immediately after their exit from the tube row, resulting in strongly eddying flow. The jets turn one way or the other because of the Canada effect. The remarkable observation is that the flow downstream of a closely spaced tube row has multiple stable configurations, which are maintained irregularly for long periods.