Vortex shedding and turbulence scales in staggered tube bundle flows

Time‐resolved LDA measurements of the axial and transverse velocity components were performed in the first 6 rows of a staggered tube bundle with relative transverse and longitudinal pitch ratios of 3.6 and 1.6, respectively. Measurements were carried out in a flow of water at a Re d of 12,858. A flow periodicity with a Strouhal number equal to 0.26 was detected, which is in agreement with published data. This periodicity was found to broaden the turbulence levels by up to 50% in some locations. Agreement between the experimental results and previously reported CFD predictions using the k ‐ ϵ model improved when this periodic component was removed from the spectra using appropriate filtering techniques. In an attempt to describe the turbulence structure more extensively, time‐ and length‐scales and dissipation rates were estimated from the filtered time‐resolved data. Integral time scales were on average equal to 4 ms and Taylor microscales 0.7 ms. Comparisons of the data with numerical predictions show promise for more extensive evaluation of CFD predictions in hture than has been possible hereto.