Abstract The waterjet propulsion is widely applied in the marine vessels over 30 knots, and the intake duct is considered as an essential component that strongly relates to the propulsion performance. This paper sheds light on the flow features inside an intake duct under mooring conditions (zero vessel speed) by using the PIV visualization technique together with the three-dimensional numerical simulations. Both the pressure and the hydraulic loss gradually decrease as the flow-rate increases. According to analyses via the Bernoulli equation, the hydraulic loss is composed of the frictional head loss (hf ～ V1.75) and the local head loss (hj ～ V2.0). A recirculation region is observed near the duct lower wall with a high-velocity flow near the upper wall, and subsequently a shear flow presents in the horizontal straight pipe with an obvious velocity gradient. Three-dimensional simulations demonstrate that the vortex pair is very strong in the recirculation region and then it gradually decreases as the fluid flows downstream. With the flow-rate increasing, the non-uniformity at the duct outlet firstly increases to a peak and then slightly decreases, while the perpendicularity at the duct outlet dramatically decreases to a minimum and then increases. This work should not only reveal some physics of the waterjet propulsion under mooring conditions, but also promote its more efficient operation.
Renfang Huang,Ruizhi Zhang,Yiwei Wang et al. Experimental and numerical investigations into flow features in an intake duct for the waterjet propulsion under mooring conditions[J]. Acta Mechanica Sinica, .