Evaporator tube bundle two-phase flow power spectrum density correlation length obtaining method and system

Abstract

The invention discloses an evaporator tube bundle two-phase flow power spectral density correlation length obtaining method and system, and the method comprises the steps: obtaining a power spectral density function of the two-phase flow of a structure based on the dimensionless reference equivalent power spectral density of the two-phase flow, the secondary side flow field parameter of the heat transfer tube structure of a steam generator and the undetermined correlation length; obtaining the Fourier half spectrum and the Fourier full spectrum of the power spectrum density function of the two-phase flow of the structure; converting the obtained power spectrum density of the frequency domain into a time domain by adopting an IFFT method to obtain a turbulence exciting force time history acting on the heat transfer tube, applying the turbulence exciting force time history to the heat transfer tube of the steam generator, and calculating the vibration response of the heat transfer tube of the steam generator induced by random turbulence excitation; determining a power spectral density function correlation length and a void fraction factor under different void fractions based on test measurement values; and according to the void fraction factors under different void fractions, adopting a fitting method to determine the calculation method of the correlation length of the two-phase flow power spectrum density function.

Description

technical field [0001] The invention relates to the technical field of reactor structural mechanics, in particular to a method and a system for obtaining the relative length of the two-phase flow power spectrum density of an evaporator tube bundle. Background technique [0002] In nuclear reactors, the mechanisms that induce flow-induced vibration mainly include turbulent flow excitation, flow-bullet instability, vortex shedding and acoustic resonance. Due to the relatively high fluid velocity in nuclear reactors, turbulent flow is present almost everywhere in steam generator heat transfer tubes, fuel rods, pumps and valves. [0003] Turbulent excitation means that turbulent flow will generate pulsating pressure on the surface of the structure passing through, and the structure will vibrate under the action of pulsating pressure. The pulsating pressure and velocity fields in turbulent flow continuously supply energy to the structure. When the main frequency of turbulent pul...

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Problems solved by technology

[0007] The two-way fluid-solid coupling method requires a large amount of computing resources and time, and the calculation cost is very high. At present, there is a large deviation between the calculated results and the measured results, and it is difficult to be used in the random turbulent excitation vibration analysis and design improvement of practical engineering problems; based on the classical random vibration theory Non-linear factors related to impact wear and fretting contact fatigue, such as clearance, collision and friction, cannot be considered

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