As one of the key parts of discharging system in the diluted zone at the bottom of high consistency bleaching tower, the spraying water pipe would be used to dilute the pulp uniformly while it was rotating, with a range from 0 to 90 rpm. Fluid dynamics of the three kinds of spraying water pipes such as straight-shaped, spindle-shaped and waist-shaped were studied by performing computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) measurements. Simulated velocity fields were compared with experiment PIV data. The results from the simulations and experiments are in good agreement. The works show that CFD simulations using the Realisable κ–ϵ model combined with the MRF technique can predict the hydrodynamic characteristics in industrial scales spraying water pipes. Spindle-shaped spraying water pipe would be better finished equal consistency spraying water.