Incompressible pulsating flow for low Reynolds numbers in orifice plates

A flow with periodic variations is known as a pulsating flow. A particularly important consequence of these flows occurs in the presence of orifice plates, which are devices related to the determination of discharge in pipes. Based on an experimental methodology, this work presents a study on the effects of pulsation variations and temporal inertia on the discharge coefficient. The work includes situations beyond those contained in the standards, particularly for liquid flows in small diameter pipes with low Reynolds numbers. The experiments were conducted on a flow bench, capable of producing pulsating flows inside pipes. For the experimental study of the transient flow, the propagation of a known flow fluctuation was related to a pressure fluctuation, allowing the dynamic calibration of the measuring system. The value of the dynamic discharge coefficient was determined, and the coefficients of static discharge and quasi-steady were compared. The results showed that the inertial effects significantly affect the value of the discharge coefficient of the orifice plate, reducing the discharge values.