The Measurement of Triple Velocity Correlation behind an Attached Ring-Type Manipulator in Turbulent Pipe Flow.

Abstract

The response of fully developed turbulent pipe flow, in which air was at a Reynolds number of 6.2×104, to a pulsewise disturbance due to an attached ring-type manipulator with a rectangular cross section, was investigated by the measurement of triple velocity correlations. The results show that the tendency of the profiles of each triple velocity correlation can explain the reason for the changes in the turbulent flow field ; this is indicated by the differences in the response to turbulent diffusion between the turbulent flnw cnmponents. Subsequently, the production term and the diffusion term of both the turbulent kinetic energy transport equation and the Reynolds shear stress transport equation near the reattached point were evaluated and compared with those of other disturbance flows. The reasons, because the present flow's separated shear layer was determined by the intermediate characteristics (between the upstanding and downward disturbance), could be illustrated by the aforesaid results. Furthermore, streamwise change of the typical value and the typical positions, which were concerned with turbulent kinetic energy diffusion towards the pipe center, were examined to clarify characteristics of the separated shear layer behind the manipulator ring in the present flow.