Abstract
In the present work, the three-dimensional heat and fluid flows around staggered pin-fin arrays are predicted using two hybrid RANS/LES models (an improved delayed detached eddy simulation (IDDES) model and a stress-blended eddy simulation (SBES) model), and one transitional unsteady Reynolds averaged Navier-Stokes (URANS) model, called k-ω SSTLM. The periodic segment geometry with a total of nine pins is considered with a channel height of 2D and a distance of 2.5D between each pin. The corresponding Reynolds number based on the pin diameter and the maximum velocity between pins is 10,000. The two hybrid RANS/LES results show the superior prediction of the mean velocity profiles around the pins, pressure distributions on the pin wall, and Nusselt number distributions. However, the transitional model, k-ω SSTLM, shows large discrepancies except in front of the pins where the flow is not fully developed. The vortical structures are well resolved by the two hybrid RANS/LES models. The SBES model is particularly adept at capturing the 3-D vortex structures after the pins. The effects of the blending function switching between RANS and LES mode of the two hybrid RANS/LES models are also investigated.
Highlights
The pin-fin structures utilized in heat exchangers, nuclear reactors, and turbine-bladed cooling systems are a common method to enhance heat transfer efficiently
A hybrid large eddy simulation (LES)/RANS model used the same grid as the unsteady Reynolds averaged Navier-Stokes (URANS) simulation, the results showed relatively better agreement than the URANS results with LES and the experimental results
(20 million cells), which is shown in Table 1, based on the adopted hybrid RANS/LES models, improved delayed detached eddy simulation (IDDES)
Summary
The pin-fin structures utilized in heat exchangers, nuclear reactors, and turbine-bladed cooling systems are a common method to enhance heat transfer efficiently. Velocity distributions, and Nusselt number distributions were acquired near the cylindrical pins and off the end-walls Their experimental results showed that the turbulence augmentation along the rows were a major parameter for heat transfer in a staggered pin-fin array, and their averaged end-wall Nusselt number had a good agreement with Metzger and Haley’s correlation and Van Fossen’s correlations. Ames et al [5] applied computational fluid dynamics (CFD) simulations with 3-D steady k-ε turbulence model series (standard, renormalization group (RNG), realizable) on the same configuration. They showed the limitations of steady k-ε turbulence models which failed to capture the unsteady vortex shedding in staggered pin-fin arrays
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