Author(s): Prof.Dr.-Ing.habil. P.-G. Franke

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Abstract: Many of the materials used in pipe manufacturing, particularly plastics, prove to be visco-elastic. As the propagation velocity of pressure waves primarily depends on the fluid bulk modulus and the elasticity of the pipe wall the above material property is of great influence in unsteady pipe flow. Furthermore the damping of the waves is caused by frictional losses in the flow as well as by the non-elasticity of the pipe material. The applicability of the method of characteristics - although being a powerful tool for the analysis of a wide range of problems - is limited in the sense that purely elastic strain behaviour has to be assumed. In order to take into account the special properties of visco-elastic pipes two methods for the computation of various types of unsteady flow were developed. By means of the impedance method it is possible to calculate a stable periodic pipe flow and, in particular, the resonance behaviour of conduits. The impulse-responsemethod based on the theory of linear systems is used for the computation of non-periodic flow, for example waterhammer analysis.

DOI: https://doi.org/10.1080/00221688309499456

Year: 1983