Analysis of condensation and secondary flows at three-way junctions using optical visualization techniques and computational fluid dynamics

Numerical assessment of mixing of humid air streams in three-way junctions and impact on volume condensation

“…A 3D CFD model was developed by Serrano et al [34] to analyze junction condensation. This model has been validated in different ways by Galindo et al [35,36]. Good accordance between CFD predictions and experimental results has been found in terms of secondary flows (measured by means of laser particle image velocimetry) and condensation patterns (observed with planar laser-induced visualization) [35], as well as condensation mass flow rates (indirectly obtained by temperature measurements with and without condensation) [36].…”

“…Junction design should minimize condensation mass flow rate to prevent harm to the LP-EGR compressor, as great impeller erosion was found at experimental impeller durability tests when 3D-CFD simulations predicted the highest condensation rates [37], which can be deemed as another prove of the validity of the 3D CFD model. Galindo et al [5,35] have observed that junction geometries that promote strong secondary flows are the ones providing higher condensation mass flow rates, but their research did not go beyond that point. The idea that volume condensation in a three-way junction may be correlated with a quantitative indicator of the mixing of its inlet streams has never been addressed before in the literature, and is the main task of this work.…”

“…This model has been validated in different ways by Galindo et al [35,36]. Good accordance between CFD predictions and experimental results has been found in terms of secondary flows (measured by means of laser particle image velocimetry) and condensation patterns (observed with planar laser-induced visualization) [35], as well as condensation mass flow rates (indirectly obtained by temperature measurements with and without condensation) [36]. Junction design should minimize condensation mass flow rate to prevent harm to the LP-EGR compressor, as great impeller erosion was found at experimental impeller durability tests when 3D-CFD simulations predicted the highest condensation rates [37], which can be deemed as another prove of the validity of the 3D CFD model.…”

Influence of the low-pressure exhaust gas recirculation injection point on engine performance

“…Serrano et al 22 developed a set of source terms to enhance 3D CFD models of LP-EGR junctions so that 3D-CFD simulations could predict condensation mass flow rate due to mixing with limited computational effort. The predictive capability of this approach has been validated in terms of secondary flows and condensation patterns, 23 distribution of condensation mass fluxes, 24 and correspondence of calculated condensation mass flow rate with subsequent impeller damage. 25 With such model, it has been established the impact of LP-EGR junction design, 23 the existence of regulating flaps 17 or the distance between EGR discharge and compressor impeller 18 on secondary flows, and enhanced air-EGR mixing.…”

“…The predictive capability of this approach has been validated in terms of secondary flows and condensation patterns, 23 distribution of condensation mass fluxes, 24 and correspondence of calculated condensation mass flow rate with subsequent impeller damage. 25 With such model, it has been established the impact of LP-EGR junction design, 23 the existence of regulating flaps 17 or the distance between EGR discharge and compressor impeller 18 on secondary flows, and enhanced air-EGR mixing. Galindo et al 18 obtained a strong positive agreement between air-EGR mixing and condensation mass flow rate, which suggests to avoid flow homogeneity at the compressor inducer plane to reduce condensation.…”