The calculation of pulsating flow in systems of plastic ducts, taking into account friction losses

The procedure which is developed for the calculation of pulsating flows takes into consideration the creep function and friction effects. The theoretical principles of the procedure are discussed, giving attention to the basic equations, the study of pressure oscillations, the wave propagation velocity, the attenuation characteristics, the linearization of friction losses in the case of laminar and turbulent flow, the relation between pressure and velocity, and the basic equations of the impedance method. The application of the described approaches is illustrated with the aid of an example involving a piston pump which delivers water through a horizontal tube made of polyvinyl chloride.