DOI: 10.1615/TSFP5
LAMINAR-TO-TURBULENT TRANSITION OF PIPE FLOWS THROUGH SLUGS AND PUFFS
ABSTRAKT
Laminar-to-turbulent transition of pipe flows occurs, for sufficiently high Reynolds numbers, in the form of slugs. These are initiated as intermittent disturbances in the entrance region of a pipe flow, and grow in length in the axial direction as they move downstream, initially as sequences of slugs. These merge at some distance from the pipe inlet to form finally the state of fully developed turbulent pipe flow. This formation process is generally known but, as shown in this paper, the randomness of slug formation does not permit detailed studies of slug flows. For this reason, a special pipe flow test rig was developed and built for detailed investigations of deterministically generated slugs. The triggering device for this is outlined. It is also employed to generate puff flows that develop out of disturbances at lower Reynolds number. With increasing Reynolds number, "puff splitting" is observed and the split-up puff develops into a slug. Thereafter, the laminar-to-turbulent transition occurs in the same way as found for slug flows.