Experimental approach to investigate the dynamics of mixing coolant flow in complex geometry using PIV and PLIF techniques

Abstract

The aim of this work is to investigate experimentally the increase of mixing phenomenon in a coolant flow in order to improve the heat transfer, the economical operation and the structural integrity of Light Water Reactors-Pressurized Water Reactors (LWRs-PWRs). Thus the parameters related to the heat transfer process in the system will be investigated. Data from a set of experiments, obtained by using high precision measurement techniques, Particle Image Velocimetry and Planar Laser-Induced Fluorescence (PIV and PLIF, respectively) are to improve the basic understanding of turbulent mixing phenomenon and to provide data for CFD code validation. The coolant mixing phenomenon in the head part of a fuel assembly which includes spacer grids has been investigated (the fuel simulator has half-length of a VVER 440 reactor fuel). The two-dimensional velocity vector and temperature fields in the area of interest are obtained by PIV and PLIF technique, respectively. The measurements of the turbulent flow in the regular tube channel around the thermocouple proved that there is rotation and asymmetry in the coolant flow caused by the mixing grid and the geometrical asymmetry of the fuel bundle. Both PIV and PLIF results showed that at the level of the core exit thermocouple the coolant is homogeneous. The discrepancies that could exist between the outlet average temperature of the coolant and the temperature at in-core thermocouple were clarified. Results of the applied techniques showed that both of them can be used as good provider for data base and to validate CFD results.

Computational fluid dynamic simulation of swirl flow in hexagonal rod bundle geometry by split mixing vane grid spacers

“…Schikorr et al [14] improved Rehme's correlation include grid spacers with mixing devices based on new pressure drop measurements. Morovere, recent studies [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] have reported that the mixing vanes cause cross and THERMAL SCIENCE: Year 2019, Vol. 23,No.…”

“…Therefore, this effect has to be taken into account in VVER assembly head calculations. Hutli et al [26] investigated experimentally the increase of mixing phenomenon in a coolant flow in order to improve the heat transfer, the economical operation and the structural integrity of VVER-440 using PIV and PLIF techniques. They obtained detailed information on the velocity, turbulence and temperature distribution for parallel turbulent flows through sub-channels of a hexagonal VVER-type rod bundle.…”

Analysis of the water flow through the simplified central tube of the VVER 440 nuclear reactor fuel assembly

“…[1], [2], [3], [4], [5]) results the necessity for attention to the effect of water sucked from perforations in central tube on temperature and velocity profile at the position of thermocouple designed to measured temperature at the fuel assembly outlet. Manufacturing of the second physical model of the fuel assembly is prepared in our faculty.…”