On determining the azimuthal velocity in round pipe in the presence of wall spiral swirls

The profile of azimuthal velocities in a longitudinal longitudinal circulation in a pipe with continuous swirlers located on the inner surface of the pipe is considered. A critical analysis of the known expressions for the azimuthal velocity profile has been carried out; a semi-empirical expression for the velocity profile has been proposed, which provides the best fit with the experimental data.