Velocity field characterization of single-phase flows across a tube bundle through spatial filter velocimetry

• Published in: Experimental thermal and fluid science 2023-09, Vol.147, p.110947, Article 110947
• Main Authors: Rocha, Douglas Martins, Kanizawa, Fabio Toshio, Hayashi, Kosuke, Hosokawa, Shigeo, Tomiyama, Akio, Ribatski, Gherhardt
• Format: Article
• Language: English
• Subjects: Pressure gradient distribution; Reynolds stresses; Spatial filter velocimetry; Tube bundle; Velocity field
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2023.110947

•Experimental data for vector velocity fields (VVF) of external flows across a tube bundle.•Investigation on the effects of the water flow rate and flow development on VVF.•Identification of mechanisms of turbulence generation.•Estimate of the pressure gradient through the experimental vector velocity field.•Spatial Filter Velocimetry was applied in a complex test section. This paper presents experimental vector velocity fields of external flows across a tube bundle to characterize the flow structure and elucidate the main mechanisms of turbulence generation. The experiments were conducted in a tube bundle test section composed of 20 rows of 4 tubes with 20 mm O.D. arranged in a normal triangular configuration with a transversal pitch per diameter ratio of 1.25. The experiments were conducted under single-phase flows with Reynolds numbers ranging from 210 to 19560, comprising transitional and turbulent flow regimes. The vector velocity fields were obtained through the Spatial Filter Velocimetry (SFV) technique, resulting in maximum spatial and temporal resolutions of 2.1 samples/mm and 49.6 kHz, respectively. The velocity measurements obtained through SFV enabled the analysis of the flow development, the vector velocity field, the flow turbulence, the velocity fluctuation along the time, and the effects of the mechanism of momentum transport on the pressure gradient. The obtained results indicate that the flow separation and the repeated intersection of opposite flows are the most relevant sources of turbulence. Moreover, the analysis of the terms of the RANS equations reveals that the convective terms are the most relevant terms for the pressure gradient.