This invention relates to an impeller device for data acquisition in a flow. It comprises a support (3) with two bearing blocks (4.1, 4.2) to hold a spindle (2) around which the impeller (1) is fitted. The spindle (2) comprises two approximately conical ends (5). The bearing blocks (4.1, 4.2) are made from a material with the lowest possible coefficient of friction and each comprises an approximately conical recess (6) into which one of the ends (5) of the spindle (2) fit.