This numerical study comparatively examines the flow and heat transfer characteristics in two rectangular channels with attached and detached pin-fin arrays at Reynolds numbers (Re) of 10000, 15000, 20000, 25000 and 30000 using the commercial code Star CD. Clearances (C) between pin-tips and endwall for the present detached pin-fin array are fixed at 1/4 pin-diameter (d). The presence of pin-to-endwall clearances modifies the endwall flow structures by way of generating the accelerating flows over the pin-tips and results in the large-scale three dimensional vorticall flows along two side walls of the detached pin-fin channel that leads to regional heat transfer enhancements. The lack of vortices and flow separations tripped by the attached pin-fins considerably reduces the inlet-to-exit pressure drops in the detached pin-fin channel. But the absence of horseshoe vortices and the downstream wakes as well as the shear-layer separations over the endwall in the detached pin-fin channel moderates the gradients of endwall Nusselt number (Nu) distributions and reduces the area averaged endwall Nu (Nu). As the endwall Nu with detached pin-fins is somewhat less than that with attached pin-fins but the channel pressure drop is much lower than that of the later, the thermal performance factors for the detached pin-fin channel are improved from those of the attached pin-fin channel.
|Number of pages||15|
|Journal||Journal of Taiwan Society of Naval Architects and Marine Engineers|
|Publication status||Published - 2009 Feb 1|
All Science Journal Classification (ASJC) codes
- Ocean Engineering
- Mechanical Engineering