Control of Swirling Flow in a Diffuser Using Various Installations

článek ve sborníku ve WoS nebo Scopus

angličtina

Admitting swirl into a diffuser leads to unsteady flow featuring a spiral vortex. This is the case of the draft tube of a water turbine operating in part load, where the spiral vortex is called vortex rope. It was shown to be the source of undesirable pressure pulsations that may under unfavorable circumstances grow to prohibitive intensity; therefore, suitable methods leading to their mitigation have long been of interest. In this work, we use a swirl generator with a diffuser and study the effect of different installations by means of both CFD simulations and experiments. The installations are based on perforated metal sheet of rotationally symmetric shape intended to induce dissipation and/or fins intended to suppress circumferential velocity. For the base case without the installations, CFD simulations with the Reynolds Stress equation Model (RSM) and scale-resolving Stress-Blended Eddy Simulation (SBES) turbulence models were carried out. Cases with the installations were simulated using RSM only. Experiments comprise pressure measurements at the diffuser wall and high-speed camera recordings of the flow visualized by air or cavitation. It was shown that installations of rotationally symmetric shapes are insufficient. Introducing fins of proper shape and placement leads to regular flow with only weak unsteadiness compared to the original irregular strongly unsteady flow.

swirling flow;instability;diffuser;vortex rope;installations

URBAN, O.; KURKOVÁ, M.; POCHYLÝ, F.

14. 2. 2023

AIP Publishing

9780735443259

AIP Conference Proceedings

0094-243X

AIP conference proceedings

2672

Spojené státy americké

8

https://pubs.aip.org/aip/acp/article/2672/1/020020/2867108/Control-of-swirling-flow-in-a-diffuser-using