Influence of the Axial Position of the Guide Vane on the Fluctuations of Pressure in a Nuclear Pump

The influence of the axial mount position of the guide vane on the pressure fluctuation in a nuclear pump (AP1000) is investigated. The characteristics of the three-dimensional flow inside the nuclear pump are analyzed by means of numerical simulation. Results indicate that when the axial relative distance between the guide vane and the pumping chamber is reduced, in conditions of "small flow," the efficiency of the pump increases, the pressure inside the pumping chamber decreases, while the losses related to the guide vane grow. Under large flow conditions, as the efficiency of the pump decreases, the losses for the guide vane and the pumping chamber increase. The pressure fluctuation in the annular pumping chamber is basically determined by the rotation frequency and the blade passing frequency. The magnitude of these fluctuations is affected by the guide vane axial position. In particular, the smallest possible amplitude is obtained when the outlet central plane of the guide vane coincides with the outlet axis of the pumping chamber.