Abstract
Laser Doppler anemometry (LDA) measurements in the fully developed turbulent flow through a one-sided rib-roughened square channel with a rib-height-to-channel-height ratio of k/H = 0.0667 and a rib-pitch-to-rib-height ratio of p/k = 9 were carried out at Reynolds numbers (based on the channel height H and the mean bulk velocity u_B) of {Re}_H = 5.0 cdot 10^4 and 1.0 cdot 10^5. Mean velocities, Reynolds normal, and shear stresses were determined. The first- and second-order statistical moments of the velocity differed slightly between both Reynolds numbers when normalized by the bulk velocity and the channel height. Deviations were attributed to a minor elongation increase in the large recirculation region behind the rib with increasing Reynolds numbers. The crucial role of turbulent diffusion was reflected in the non-coincidence of the maximum primary mean shear and the Reynolds normal stress as well as outward drifts of the Reynolds stress peaks along the rib crest. Turbulent diffusion contributed significantly to the turbulence kinetic energy (TKE) budget near the rib crest and within the separated shear layer, while mean convection made a remarkable contribution only at the rib leading edge. The detailed first- and second-order moments provide a basis for the validation of computational methods and turbulence models.Graphic abstract
Highlights
Attached ribs are an appropriate surface structure for increasing the heat transfer in the cooling ducts of gas turbine blades (Han 2004), solar receivers (Hans et al 2009), or thermally highly loaded reactor components (Ruck et al 2019)
Laser Doppler anemometry (LDA) measurements in the fully developed turbulent flow regime of a one-sided rib-roughened square channel were carried out to investigate the turbulent flow at Reynolds numbers of ReH = 5.0 ⋅ and 1.0 ⋅
The statistical moments exhibited a slight Reynolds number dependency when normalized by the bulk velocity and the channel height
Summary
Attached ribs are an appropriate surface structure for increasing the heat transfer in the cooling ducts of gas turbine blades (Han 2004), solar receivers (Hans et al 2009), or thermally highly loaded reactor components (Ruck et al 2019). Fundamental research about turbulent flows over walls roughened by transverse ribs of the height k has been
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