Prerotation flow measurement

Different measuring methods relating to the prerotation flow in the entrance pipe of radial pumps are analyzed. The appearance of the prerotation flow is a result of the complicated fluid flow model, which appears as a consequence of the pump operating out of design limits and reduces pump efficiency. The goal of this contribution is in estimating the best measuring method, taking into account the inconvenience of conventional hot-wire and laser-Doppler anemometry. Therefore, two measuring systems—multiblade (ASB) and single blade (ASSB) anemometer—are introduced, analyzed and compared. The advantages of the introduced measuring system—ASB—are in its simple construction and simple use and its low price. The direction and swirl flow intensity in the entrance pipe of radial pumps and fans could be measured using this method.