Abstract

When a fluid enters a rotating circular pipe a swirl boundary layer with thickness of δ̃s appears at the wall and interacts with the axial momentum boundary layer with thickness of δ̃. We investigate a turbulent flow applying Laser-Doppler-Anemometry to measure the circumferential velocity profile at the inlet of the rotating pipe. The measured swirl boundary layer thickness follows a power law taking Reynolds number and flow number into account. A combination of high Reynolds number, high flow number and axial position causes a transition of the swirl boundary layer development in the turbulent regime. At this combination, the swirl boundary layer thickness as well as the turbulence intensity increase and the latter yields a self-similarity. The circumferential velocity profile changes to a new presented self-similarity as well. We define the transition inlet length, where the transition appears and a stability map for the two regimes is given for the case of a fully developed axial turbulent flow enters the rotating pipe.

Highlights

  • At part load of a turbo machine below a critical flow number φ := U ̄ /(RΩ ) < φc, with the average axial velocity U ̄ and circumferential velocity of the pipe RΩ, flow separation occurs, the so called part load recirculation

  • This paper investigates experimentally the evolution of the swirl boundary layer and the circumferential velocity profile at high Reynolds number and high flow number when a fully developed axial turbulent flow enters the rotating pipe

  • We vary Reynolds number, flow number and axial position to investigate the evolution of the swirl

Read more

Summary

Introduction

At part load of a turbo machine below a critical flow number φ := U ̄ /(RΩ ) < φc, with the average axial velocity U ̄ and circumferential velocity of the pipe RΩ , flow separation occurs, the so called part load recirculation. E.g tip vortex, are avoided by using a rotating pipe instead of blades yielding an undisturbed flow. The outcome of this investigation is useful to analyse and to predict part load recirculation, flows in rotating gaps, e.g. secondary air flow of a gas turbine, and to clarify the inlet condition of turbo machine, e.g. a shrouded turbo machine. This investigation supports the designers of the mentioned parts of a turbo machine

Methods
Results
Discussion
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.