Study on transient flow model of viscoelastic pipeline based on viscous and unsteady friction effect

The existing transient flow model of viscoelastic pipe fails to fully consider the coupling effect of material-dependent viscoelastic creep behavior and unsteady friction effect, and underestimates the attenuation process of pressure wave. Therefore, this paper studies a new coupling numerical model, which combines the generalized Kelvin-Voigt constitutive model of wall viscoelasticity with the Vardy dynamic friction model, and uses a parameter identification method of hybrid optimization strategy to invert the creep characteristic parameters. Compared with the traditional steady-state friction model and the Vardy friction model, the accuracy and computational efficiency of the new model are verified. The results show that the steady-state friction model and the Vardy friction model are significantly different from the experimental values in terms of pressure peak and phase offset. The maximum percentage error of the peak pressure at the valve is 19.13% for the Vardy friction model. After considering the viscous effect and the unsteady friction effect, the simulation results are in good agreement with the experimental data, and the maximum percentage error of the peak pressure is only 1.65%. In addition, under the same calculation conditions, the new model reduces the calculation time by about 80% compared with the traditional Vardy friction model, and shows excellent performance in terms of accuracy and efficiency, which can provide an accurate and efficient simulation method for the hydraulic transition process of viscoelastic pipelines.