Heat exchangers are used in many practical applications
throughout the world. For applications involving liquidto-gas heat transfer, the gas-side accounts for the vast
majority of the thermal resistance. One way of improving
the heat transfer is by the use of vortex generators (VGs)
such as winglets. VGs generate vortices that interact
with the thermal boundary layer and thereby enhance
the heat transfer. The present work investigates how
variations in winglet height and longitudinal pitch distance
affect the flow phenomena and resulting heat transfer
and pressure loss for rectangular winglet pair VGs in a
staggered periodic arrangement. A Large Eddy Simulation
(LES) model to simulate periodic flow and heat transfer
is developed for the numerical investigations. To validate
the LES model, an experimental setup is developed to
facilitate Laser Doppler Anemometry (LDA) measurements.
The LDA measurements and LES simulations show good
correspondence with a mean deviation of ≈ 5 %. The
numerical investigations prove the highest performance at a
smaller winglet height and larger longitudinal pitch distance,
which is attributed to the fact that the generated vortices in
this configuration have a good interaction with the thermal
boundary layer without causing a significant pressure loss.