Air flow in a tube with a diverging inlet: I. Development of the turbulent velocity profile

Abstract

The results from an experimental study of the development of air velocity profiles in a vertical 6.25‐in. I. D., 28.5‐ft. long aluminum tube with a diverging conical entrance are reported. Using the axial development of centerline velocity as a starting‐length criterion, a maximum and asymptotic value was approached at 40 diameters from the tube entrance. The starting length was found to increase with increasing Reynolds number. The large center‐line velocity associated with the jetting of air from a 1‐in. I. D. tube into the diverging conical entrance enabled a more rapid development of the velocity profile than for the well known case of a converging rounded entrance. A limited comparison of undeveloped and fully developed velocity profiles in the turbulent core region of the 6.25‐in. tube was also made over Reynolds numbers from 9,000 to 55,000.

Developing turbulent flow in concentric annuli: An analytical and experimental study

“…Therefore, again according to different investigators, the definition of the fully developed flow is different. For example, OLso?~ and SPARROW [9] whose definition of the entrance length is based on (a), defined that the value within 5% of its limiting value constitutes a fully developed flow, whereas, LA?~A and CHRISTIA?~SE~ [23] who used (b) above for their definition of the entrance length assumed that a value within 1.0% of the limiting, fully developed value constitutes fully developed Core Velocity Distribution, Entrance Region.…”