Analysis of pressure distribution of turbulent asymmetric flow in a flat duct symmetric sudden expansion with small aspect ratio

Abstract

This paper describes the pressure distribution of turbulent airflow through a flat duct containing one-dimensional symmetric sudden expansion in cross-sectional area encountered frequently in plate heat exchangers and other devices of practical importance. The pressure distributions of turbulent asymmetric airflow through constant width flat ducts having modest expansion ratios of 2, 2.5 and 3, aspect ratios of the expansion of 0.40, 0.26 and 0.20 and modest area ratios of the expansion of 1/3, 1/2.5 and 1/2 were investigated experimentally. The axial and vertical pressure distributions of the turbulent asymmetric flow with relatively small Reynolds numbers (Re D h = uD h / = 12 000, 4887 and 4125) in downstream cross section of the duct were analyzed. The variations of pressure coefficient with local Reynolds numbers were also investigated. Turbulent flow in flat ducts with symmetric sudden expansion has not sufficiently been studied contrary to axisymmetrical or two-dimensional case for which a large numbers of papers can be found in the literature. This experimental study fulfills this gap and shows that the flow is asymmetric as in a two-dimensional case. It also brings interesting data for numerical simulations for the presented flat duct configurations. These data concern the axial and vertical distribution of pressure coefficient, the axial velocity in the duct and Reynolds numbers based on the hydraulic diameter, the step height or the local axial distance of the duct. The results obtained complement and extend the previous results, and show that the expansion ratio and Reynolds number affect the flow field.

Unsteady shallow meandering flows in rectangular reservoirs: A modal analysis of URANS modelling

“…The hydraulic and geometric conditions leading to symmetric and asymmetric jets were extensively studied experimentally (Aloui and Souhar, 2000;Camnasio et al, 2011;Canbazoglu and Bozkir, 2004;Dufresne et al, 2010a;Kantoush et al, 2008;Mullin et al, 2003;Oca and Masaló, 2007), numerically (Camnasio et al, 2013;Dewals et al, 2008;Dufresne et al, 2011;Esmaeili et al, 2016;Khan et al, 2013;Peltier et al, 2015;Peng et al, 2011;Stovin and Saul, 2000) and analytically (Westhoff et al, 2018). In contrast, less attention was given to the case of a meandering jet, despite its engineering relevance.…”

Meandering jets in shallow rectangular reservoir

“…Although the physics of the symmetric and asymmetric configurations are now relatively well understood (Mullin et al, 2003, Canbazoglu and Bozkir, 2004 Meandering jets in shallow rectangular reservoir Y. Peltier, S. Erpicum, P. Archambeau, M. Pirotton & B. Dewals ArGEnCo Department, Research Group Hydraulics in Environmental and Civil Engineering (HECE), University of Liège, Liège, Belgium ABSTRACT: In this article, meandering flows in a shallow rectangular reservoir are experimentally and numerically investigated. Two experiments were performed in a smooth shallow horizontal flume and the surface velocity fields were measured by Large-Scale PIV (LSPIV).…”