A study proves that pipeline turbulence can be destabilised in a way that returns it to a more efficient flow.
Scientists, who work out of the Institute of Science and Technology in Austria, developed the technique as an alternative to just minimising the effects of turbulence. According to the article, the energy used to pump fluids, from water, to natural gas, to oil, accounts for about 10% of electrical energy consumption globally.
In order to return to the most efficient flow (called a laminar flow, where fluid travels in layers that don’t mix), turbulence is initially increased to destabilise the current in such a way that it naturally reverts to a laminar flow.
“Nobody knew that it was possible to get rid of turbulence in practice. We have now proven that it can be done. This opens up new possibilities to develop applications for pipelines,” said Jakob Kühnen, co-first author of the study.
Returning to laminar flows and reducing drag could reduce the energy required to pump liquid by up to 95%.
One cause of turbulence is the difference in the velocity of liquid next to the pipe wall to that in the centre due to friction between the pipe and the liquid. The researchers managed this effect by placing rotors in the flow that reduce the difference between the speed of the liquid at the centre of the pipe and at the edge.
Another method was to inject fluid through the pipe wall to alter the velocity of the liquid.
Although their techniques has been shown only at relatively low velocities, the group is confident of scaling-up to meet industrial requirements: “In computer simulations, we have tested the impact of the flat velocity profile for Reynolds numbers up to 100.000, and it has worked absolutely everywhere. The next step is now to make it work also for high speeds in the experiments,” said Björn Hof, another co-first author.