Experimental study of the convective heat transfer from in-line and staggered configurations of two wall-mounted cubes

The paper reports on the experimental investigation of the effects of the relative obstacle position on the convective heat transfer from a configuration of two wall-mounted cubes located in a fully developed turbulent channel flow. Both in-line and staggered arrangements were studied for various streamwise (Sx/H) and spanwise (Sz/H) distances. Distributions of the local heat transfer coefficient (h) were obtained from infrared thermography and local convective heat flux analyses. Laser Doppler anemometry measurements and flow visualisations were performed to document the flow and turbulence fields around the cubes. The results showed a large variation in the distribution of the local convective heat transfer for the various in-line and staggered configurations studied. While the in-line arrangements were featured by symmetric flow pattern and heat transfer distributions, the staggered arrangements showed distinct asymmetric pattern for certain combinations of Sx/H and Sz/H. Flow reattachment caused typically a monotonic decay of the convective heat transfer. On the other hand, flow separation caused distinct heat transfer extrema at the cube faces. In addition, the effect of vortex shedding on the convective heat transfer of the downstream cube was studied with a fast-responding heat flux sensor. Despite distinct variation in the distribution of the time-averaged heat transfer coefficient, the cube-averaged heat transfer coefficients appeared to be independent of the relative placement of the two cubes.