Hydrodynamics of turbulent liquid flow in the entrance region of circular tubes

Presented are the main results and analysis of work on experimental research of the turbulent flow of fluid in the inlet section of straight channels of a circular cross-section. The experiments staged with the inlet arrangements of various geometries prove that the length of the initial section depends on the initial turbulence of the flow. The maximum stabilization length of the velocity profile is observed in case of a smooth rounded inlet of the channel. The static pressure gradient acquires the stabilized values on a length of a pipe two or three times less than the velocity profile. Certain experimental data have revealed the variation of the velocity profile in the initial section from the ''wall law'' of the stabilized flow. The effect of the Reynolds number on the length of the inlet section has not been reliably extablished