Experimental investigation of turbulent flow characteristics in cross-flow planes of a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si35.svg"><mml:mrow><mml:mn>5</mml:mn><mml:mo>×</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:math> rod bundle with a spacer grid

This study summarizes experimental investigations of the flow field characteristics in cross-flow planes a 5×5 rod bundle with spacer grid and split-type mixing vanes. Under isothermal atmospheric conditions, velocity fields are obtained by applying matched-index-of-refraction time-resolved particle image velocimetry (TR-PIV) techniques for Reynolds numbers Re1=14,000 Re2=28,000. The axially start from tips vanes end at 11.73Dh (Dh is hydraulic diameter bundle). From acquired TR-PIV fields, statistics such as in-plane mean vorticity, turbulent kinetic energy stress computed presented four interest located 0,2Dh,5Dh, 11Dh. Two counter rotating vortices observed near grid. After change elevation to z/Dh=5, merge into single vortex centered middle subchannel. In addition, turbulence elevations discussed through calculations integral length scales spectral analysis. No dominant frequency observed, strongly influenced proximity mass transfer between subchannels associated rate calculated all elevations; hence, this step toward improving correlations currently used subchannel codes. Results secondary intensities, lateral profiles contours compared large-eddy simulation results literature Re1=14,000, reasonable agreement observed.