Method of liquid flow measurement using a modified PIV method

W pracy przedstawiono wyniki badań pomiaru prędkości ruchu cieczy. Prędkość określono na podstawie zdjęć fotograficznych z wizualizacji ruchu cieczy, w której znajdowały się znaczniki optyczne. Przedstawiona metoda umożliwia wyznaczenie prędkości ruchu cieczy z dokładnością do kilku procent wartości mierzonej.Phenomena related to the flow around different types of obstacles belong to one of the most difficult issues of fluid mechanics. Fluid flowing to the obstacle is disturbing what is associated with the formation of vortices. The frequency and intensity of vortices depend on flow and type of obstacle. The phenomenon is used in vortex flow meters. The paper present the test stand of flow visualization for vortex bluff bodies of vortex flowmeter. Very important parameter, which is necessary to designate in testing space is flow velocity. The paper proposes a method of measuring the velocity of liquid motion based on the image recorded during the visualization. The flow velocity was determined by the photographic images from the fluid flow visualization in which the tags were located. Pictures were taken with a camera with a long exposure time. The proposed method enables the determination of the fluid velocity to a certain percentage of the measured value. The uncertainty of this measurement significantly depends on the value of the measured velocity. In order to maintain the desired measurement accuracy, it is necessary to adjust the exposure time accordingly