Impact of fluid viscoelasticity on the pressure wave in laminar fluid hammer in helical tubes-an experimental study

The fluid hammer phenomenon can cause severe damages to the hydraulic systems. As its potential exists in systems with viscoelastic fluids as the working fluid, investigating the impact of viscoelasticity on this phenomenon has been the primary target of this study. The built experimental setup includes copper and low-density polyethylene tubes, and dilute polyacrylamide solutions are implemented as the viscoelastic fluid. Results indicated that the viscoelasticity signifies the pressure wave attenuation. The pressure wave damping rate was 14.67% more considerable in the 400 ppm solution than water. Increasing the Deborah number by 41.59% in copper tube, and 38.72% in polyethylene tube led to 21.05 and 3.96% rise in the wave rate of attenuation, respectively. The same growth in Deborah number has caused a descending trend in the acoustic wave speed relative to water, by 0.88% decrease in the copper and 2.90% decrease in the polyethylene tube. Also, despite the results with water in the copper tube, the time distance of subsequent peaks was unequal in tests with viscoelastic fluids.