LAUSR

A dual-technique-based inline strategy was investigated in this study as a sustainment to conventional-technique skills in terms of limitation of wave oscillation period spread-out. Instead of the single polymeric short section employed by the latter technique, the former is based on replacing an up- and downstream short section of the primitive piping system using another couple made of polymeric pipe-wall material. Numerical computations used the method of characteristics for the discretization of unconventional water-hammer model based on the Vitkovsky and the Kelvin–Voigt formulations. The efficiency of the dual technique was considered for two operating conditions associated with up- and downsurge frames. Moreover, two pipe-wall material types were utilized for short-section pipe wall, namely the HDPE or LDPE materials. Additionally, the conventional technique was also addressed in this study, for comparison purposes. First, analyses of pressure-head, circumferential-stress and radial-strain wave patterns, along with wave oscillation periods examination, confirmed that the dual technique could improve the efficiency of the conventional one, providing acceptable trade-off between the attenuation of pressure-head and circumferential-stress peaks (or crests), and limitation of period spreading and radial-strain amplification. Second, a parametric study of the sensitivity of the wave damping to the employed short-section dimensions was performed in terms of short-section length and diameter. This parametric study helped estimate the near-optimal values of the short-section dimensions.