Any measurements made at the end of a duct or hose suffers from the turbulence problems. Even the spiral wire in the flex hose will cause problems.

The best measurements are made with a straight section of pipe and making measurements in the middle to avoid turbulence. Also, need to make appropriate measurements across the section.

I did some testing with a fan anemometer at the end of a pipe and got numbers that varied widely and not close to the actual flow.

On the Australian forum, wood work forums . com, BobL does a technical description of the precise way to measure flow and describes the issues of measuring at the end of a duct.