Flow structures and heat transfer in repeating arrangements of staggered rectangular winglet pairs by Large Eddy Simulations: Effect of winglet height and longitudinal pitch distance

Allan Bjerg, Kristian Boe Christoffersen , Henrik Sørensen, Jakob Hærvig

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Large Eddy Simulations (LES) of the flow in repeating arrangements of staggered rectangular winglet pairs are presented to get a better understanding of the detailed flow and heat transfer enhancing mechanisms. Simulations are performed for various geometrical configurations with the winglet height h and longitudinal pitch distance Lp being varied in the ranges h/H in [0.3;0.7] and Lp/H in [3;7] at Re = ubH/nu = 700 and Pr = 0.71.

The results show that three different types of vortices are generated by the winglet pairs: main longitudinal vortices, corner vortices and induced vortices, with the main longitudinal vortices being the main contributor to heat transfer enhancement. It is found that the heat transfer and pressure loss increase with increasing winglet height and decrease with increasing longitudinal pitch distance. The winglet height proves to have the highest impact on both the heat transfer and pressure loss. Furthermore, the results show that local heat transfer can effectively be increased on the fin side by utilising smaller winglet heights. For higher winglet heights local heat transfer is observed to be more equally distributed on both sides.

Overall, pressure loss increments f/f_0 between 3.3 and 33.5 and heat transfer enhancements Nu/Nu0 between 2.2 and 4.6 are found. When introducing the performance factor eta=(Nu/Nu0)/(f/f_0)^{1/3} as a measure for heat transfer enhancement relative to pressure loss, the optimal geometries generally have a combination of lower winglet heights and higher longitudinal pitch distances.
OriginalsprogEngelsk
TidsskriftInternational Journal of Heat and Mass Transfer
Vol/bind131
Sider (fra-til)654-663
Antal sider10
ISSN0017-9310
DOI
StatusUdgivet - mar. 2019

Fingerprint

winglets
Large eddy simulation
large eddy simulation
Flow structure
heat transfer
Heat transfer
Vortex flow
vortices
augmentation
Fins (heat exchange)
fins

Citer dette

@article{b61df84808d14b6a9c89ffa9ee874a04,
title = "Flow structures and heat transfer in repeating arrangements of staggered rectangular winglet pairs by Large Eddy Simulations: Effect of winglet height and longitudinal pitch distance",
abstract = "Large Eddy Simulations (LES) of the flow in repeating arrangements of staggered rectangular winglet pairs are presented to get a better understanding of the detailed flow and heat transfer enhancing mechanisms. Simulations are performed for various geometrical configurations with the winglet height h and longitudinal pitch distance Lp being varied in the ranges h/H in [0.3;0.7] and Lp/H in [3;7] at Re = ubH/nu = 700 and Pr = 0.71.The results show that three different types of vortices are generated by the winglet pairs: main longitudinal vortices, corner vortices and induced vortices, with the main longitudinal vortices being the main contributor to heat transfer enhancement. It is found that the heat transfer and pressure loss increase with increasing winglet height and decrease with increasing longitudinal pitch distance. The winglet height proves to have the highest impact on both the heat transfer and pressure loss. Furthermore, the results show that local heat transfer can effectively be increased on the fin side by utilising smaller winglet heights. For higher winglet heights local heat transfer is observed to be more equally distributed on both sides.Overall, pressure loss increments f/f_0 between 3.3 and 33.5 and heat transfer enhancements Nu/Nu0 between 2.2 and 4.6 are found. When introducing the performance factor eta=(Nu/Nu0)/(f/f_0)^{1/3} as a measure for heat transfer enhancement relative to pressure loss, the optimal geometries generally have a combination of lower winglet heights and higher longitudinal pitch distances.",
keywords = "Rectangular winglet pairs, Vortex generator, Parametric variation, Winglet height, Longitudinal pitch distance, Large Eddy Simulation (LES), Periodic flow",
author = "Allan Bjerg and Christoffersen, {Kristian Boe} and Henrik S{\o}rensen and Jakob H{\ae}rvig",
year = "2019",
month = "3",
doi = "10.1016/j.ijheatmasstransfer.2018.11.015",
language = "English",
volume = "131",
pages = "654--663",
journal = "International Journal of Heat and Mass Transfer",
issn = "0017-9310",
publisher = "Pergamon Press",

}

TY - JOUR

T1 - Flow structures and heat transfer in repeating arrangements of staggered rectangular winglet pairs by Large Eddy Simulations: Effect of winglet height and longitudinal pitch distance

AU - Bjerg, Allan

AU - Christoffersen , Kristian Boe

AU - Sørensen, Henrik

AU - Hærvig, Jakob

PY - 2019/3

Y1 - 2019/3

N2 - Large Eddy Simulations (LES) of the flow in repeating arrangements of staggered rectangular winglet pairs are presented to get a better understanding of the detailed flow and heat transfer enhancing mechanisms. Simulations are performed for various geometrical configurations with the winglet height h and longitudinal pitch distance Lp being varied in the ranges h/H in [0.3;0.7] and Lp/H in [3;7] at Re = ubH/nu = 700 and Pr = 0.71.The results show that three different types of vortices are generated by the winglet pairs: main longitudinal vortices, corner vortices and induced vortices, with the main longitudinal vortices being the main contributor to heat transfer enhancement. It is found that the heat transfer and pressure loss increase with increasing winglet height and decrease with increasing longitudinal pitch distance. The winglet height proves to have the highest impact on both the heat transfer and pressure loss. Furthermore, the results show that local heat transfer can effectively be increased on the fin side by utilising smaller winglet heights. For higher winglet heights local heat transfer is observed to be more equally distributed on both sides.Overall, pressure loss increments f/f_0 between 3.3 and 33.5 and heat transfer enhancements Nu/Nu0 between 2.2 and 4.6 are found. When introducing the performance factor eta=(Nu/Nu0)/(f/f_0)^{1/3} as a measure for heat transfer enhancement relative to pressure loss, the optimal geometries generally have a combination of lower winglet heights and higher longitudinal pitch distances.

AB - Large Eddy Simulations (LES) of the flow in repeating arrangements of staggered rectangular winglet pairs are presented to get a better understanding of the detailed flow and heat transfer enhancing mechanisms. Simulations are performed for various geometrical configurations with the winglet height h and longitudinal pitch distance Lp being varied in the ranges h/H in [0.3;0.7] and Lp/H in [3;7] at Re = ubH/nu = 700 and Pr = 0.71.The results show that three different types of vortices are generated by the winglet pairs: main longitudinal vortices, corner vortices and induced vortices, with the main longitudinal vortices being the main contributor to heat transfer enhancement. It is found that the heat transfer and pressure loss increase with increasing winglet height and decrease with increasing longitudinal pitch distance. The winglet height proves to have the highest impact on both the heat transfer and pressure loss. Furthermore, the results show that local heat transfer can effectively be increased on the fin side by utilising smaller winglet heights. For higher winglet heights local heat transfer is observed to be more equally distributed on both sides.Overall, pressure loss increments f/f_0 between 3.3 and 33.5 and heat transfer enhancements Nu/Nu0 between 2.2 and 4.6 are found. When introducing the performance factor eta=(Nu/Nu0)/(f/f_0)^{1/3} as a measure for heat transfer enhancement relative to pressure loss, the optimal geometries generally have a combination of lower winglet heights and higher longitudinal pitch distances.

KW - Rectangular winglet pairs

KW - Vortex generator

KW - Parametric variation

KW - Winglet height

KW - Longitudinal pitch distance

KW - Large Eddy Simulation (LES)

KW - Periodic flow

U2 - 10.1016/j.ijheatmasstransfer.2018.11.015

DO - 10.1016/j.ijheatmasstransfer.2018.11.015

M3 - Journal article

VL - 131

SP - 654

EP - 663

JO - International Journal of Heat and Mass Transfer

JF - International Journal of Heat and Mass Transfer

SN - 0017-9310

ER -