Experimental and numerical investigation on flow and heat transfer in large-scale, turbine cooling, representative, rib-roughened channels

Abstract

This paper deals with the application of a three-dimensional Navier-Stokes solver for the prediction of steady viscous compressible flow and heat transfer in a square channel with one rib-roughened wall. The computation results are compared with detailed experiments carried out at the von Karman Institute. The two-dimensional computations agree rather well with the experiments for the prediction of the aerodynamics, even if the recirculation length is overestimated. In this case, a k-l turbulence model seems to be sufficient. However, heat transfer between the ribs is poorly matched except when a thermal ASM (algebraic stress model) turbulence model (GGDH, or generalized gradient diffusion hypothesis), which computes the u iθ (velocity-temperature) correlations by algebraic equations, is used. The three-dimensional computations capture the correct position of the reattachment point with the k-l turbulence model. It is nevertheless necessary to use the ASM turbulence model to find vortices turning the correct way in the cross-sections. These are indeed secondary flows of the second kind which are mainly due to turbulence anisotropy when the ribs are inclined at 90° to the flow direction.

Experimental validation of large eddy simulations of flow and heat transfer in a stationary ribbed duct

“…The accurate prediction of these two curves is difficult to achieve because of the recirculation of flow near the ribs and the localized secondary flow effect. Many computational studies have attempted to correctly predict this smooth wall heat transfer effect using different turbulence models with little success (Ooi et al, 2002;Arts et al, 1997;Saidi and Sundén, 2001;Sleiti and Kapat, 2004). In the 180°bend region, a mass transfer experiment by showed results for a channel with geometry similar to that of the present study (e/D h = 0.094, P/ e = 10) with a Reynolds number of 30,000.…”

“…Two two-dimensional calculations by Liou et al (1992Liou et al ( , 1993b) used a k-e-A model, which is a standard k-e model coupled with an Algebraic Stress Model (ASM), and were able to account for the anisotropy of turbulence. Calculations using a number of different turbulence models by Arts et al (1997) showed that a three dimensional k-l model (similar to k-e) was not sufficient in predicting the secondary flows and an ASM was required. A comparison between an eddy-viscosity model (EVM) and an ASM reported that the average heat transfer on the side wall (which is most affected by secondary flows) was predicted to within 5%, but contours of the regions showed predictions that were completely different from what the experimental measurements showed (Saidi and Sundén, 2001).…”

“…Except in the immediate vicinity of the rib, the secondary flow is weak. Because of the highly localized nature of the secondary flow, which is mostly driven by instantaneous vorticity at the rib junction with the smooth wall, it is quite challenging to predict with eddy-viscosity RANS models (Prakash and Zerkle, 1995;Ooi et al, 2002;Arts et al, 1997;Saidi and Sundén, 2001). This is unlike the secondary flows experienced in skewed ribs (Bonhoff et al, 1997;Shih et al, 1998;Bonhoff et al, 1999;Astarita et al, 2002;Astarita and Cardone, 2003;Lin et al, 2001;Jang et al, 2001;Al-Qahtani et al, 2002a,b;Iacovides et al, 2003;Abdel-Wahab and Tafti, 2004b), which are much stronger and coherent and are driven by the rib geometry and hence easier to predict.…”

Convective Heat Transfer and Infrared Thermography

“…The effects of rib turbulators have been investigated by many researchers; in particular the work of Ekkad and Han,6 Ekkad et al ,7 Park et al ,8 Akella and Han,9 and Arts et al 10 are acknowledged. The present tests dealt with a square channel, 80 mm side length, 2,000 mm long, which was tested both with and without ribs.…”

combined numerical and experimental study of heat transfer of a turbine airfoil cooling channel with angled ribs and a 180-degree u-bend turn

“…T. Arts et al combined experimental and 2D numerical methods to investigate heat transfer in rib-roughened channels. [9] J. E. Dees, D. G. Bogard., performed experimental and computational investigation to study a cooling channel with 90-degree ribs in 2012.…”