Mathematical modeling of the coolant flow in a Venturi nozzle at high medium parameters by means of the finite element method

Venturi nozzles have found quite wide application in various industries. The paper considers the design and operating modes of the basic leak limiter made in the form of an asymmetric Venturi nozzle which is one of the technological systems of the first circuit of the Novovoronezh NPP-2 power unit No. 1 (NPP-2006 project). Methods for modeling in the ANSYS CFX software and hardware complex using the finite element method and operating modes of the device to assess its effectiveness in emergency mode and normal operation mode are presented. The results of thermohydraulic calculations of the stationary operation mode of the leak limiter insert are given, comparison with the results according to basic calculation methods is performed. The complexity of the task being performed lies in the fact that the leak limiter is installed on the pipeline where the coolant has a temperature significantly higher than the saturation temperature consistent with the pressure of the medium into which the leakage occurs when the pipeline breaks. The section of the cylindrical neck of the minimum cross-section provides boiling of the liquid within its length, which leads to partial self-locking of the leaking coolant flow because of enabling a critical flow mode; in essence, this refers to the solution to the problem of a two-phase medium flow.

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