Turbulent Flow Characteristics in an Axial-flow Pump at Direct and Reverse Modes

A reversible axial-flow pump equipped with S-shaped blades is investigated. Numerical simulation is employed as the major instrument to virtually visualize complex turbulent flows in the pump at direct and reverse operation modes. Cavitation is taken into account as well. Pressure fluctuations near the inlet and outlet of the impeller are obtained with unsteady simulation. At nominal flow rate, a relative difference of pump head of 15% is manifested between direct and reverse operation modes. At direct mode merely, cavitation zones are aggregated near the leading edge of the blade and assume a small volume fraction. The contribution of pump shaft is remarkable in terms of affecting pressure fluctuation characteristics upstream of the impeller. Characteristic frequencies immediately downstream of the impeller are analogous for the two operation modes and pressure fluctuation magnitudes are large relative to their counterparts upstream of the impeller.