## Development of CFD model of RCP set

The CFD model of the flow path of reactor coolant pump set (RCP) is developed in OKB “GIDROPRESS”. The calculated area includes the flow paths of suction nozzle, spherical casing, impeller, guiding device, delivery nozzle, inlet and outlet pipelines. The gap between the rotor and stator parts is included into the calculated area in order to take into account a reverse flow from the delivery into suction area. The calculational mesh consists of polyhedral test volumes, their total sum is 20 million.

The mathematical model consists of Navier-Stokes equations averaged as per Raynolds, and the equations of continuity. Turbulence model k-ε Realizable is applied for modeling turbulent flow. The sample circuit of the area of convective terms and the time of non-steady terms have the second accuracy order.

The technologies of moving reference frame (MRF) and rigid body motion (RBM) are used to take into account the rotary motion of impeller. The MRF technology models rotation of impeller by adding frame velocity to the coolant velocity in blade channels of impeller, as well as taking into account inertial force and Coriolis force acting in coolant flow in blade channels of impeller. The RBM technology models rotation of impeller by turn at each time step of impeller walls by the respective angle. With this, the calculational mesh shall be renewed in the area of contact of the rotor and stator parts at each time step.

A series of calculations is performed with the help of the developed CFD model, and a result, the distribution of pressure and velocity vector module is obtained in the calculated area. The calculations were performed in two stages. The MRF technology was applied at the first stage in order to obtain stationary conclusion. The RBM technology was applied at the second stage using the data obtained at the first stage as the initial approximation. The performed calculational study the working characteristic of RCP set is obtained and its comparison with the results of the experiment showed good agreement

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