An Acceleration Method for Solving Simulation of Boiling in a Typical Channel of Nuclear Reactor

Abstract

The invention discloses an acceleration method for boiling simulation solution in a typical channel of a nuclear reactor. Calculate the convergence judgment. On the basis of solving the boiling model of the usual two-fluid model, the process of judging the excess of the cavitation share and the pressure correction process is added. In each step of iteration, the average cavitation share on each section in the channel is solved. Use the empirical relationship to calculate the section pressure, obtain the new pressure difference, and re-solve the pressure-velocity coupling equation. Compared with the previous solution of the Euler two-fluid equation, the present invention can timely correct the pressure distribution in the channel under the high cavitation fraction, avoid the backflow phenomenon caused by the mismatched pressure-velocity field, and quickly achieve the physical real pressure distribution, thereby accelerating the convergence. , providing precise two-phase parameters for reactor design, so as to achieve the goal of reducing safety margin and improving reactor design economy.

Description

technical field [0001] The invention relates to a computational fluid dynamics simulation technology in a typical channel of a nuclear reactor, in particular to a boiling simulation solution acceleration convergence method. Background technique [0002] The safe design and operation of reactors requires the prediction of flow heat transfer in typical channels within the reactor system. The design tool used in the past is mainly the reactor system program, which is a one-dimensional simplified simulation of the reactor system channel. Its prediction depends on a large number of experiments and has a large uncertainty. It is necessary to introduce a large safety margin into the reactor design. Sacrifice economy for safety. In order to improve the economics of nuclear reactors, it is necessary to carry out three-dimensional fine simulation of the flow in the channels of each component of the reactor system, thereby reducing the design safety margin. Among the parameters relat...

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Problems solved by technology

However, when using this method to solve the Euler two-fluid model, especially under the physical condition of high cavitation fraction with boiling phenomenon, due to the sudden increase of the gas phase fraction, the liquid phase velocity will increase suddenly, which will make the pressure velocity The coupling relationship is out of balance. At this time, if the pressure-velocity relationship is used to solve the velocity equation, unreasonable backflow will occur

Eliminating the influence of backflow requires several iterations, which greatly reduces the convergence speed of the calculation; when the backflow condition is not set properly, it will even cause the calculation to diverge, which directly affects the calculation amount and calculation time of the simulation

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