Heat Transfer Enhancement Within a Turbine Blade Cooling Passage Using Ribs and Combinations of Ribs With Film Cooling Holes

Abstract

A transient heat transfer method using liquid crystals has been applied to a scale model of a turbine rotor blade passage. Detailed contours of local heat transfer coefficient are presented for the passage in which the heat transfer to one wall was enhanced first by ribs and then with ribs combined with holes. The hole geometry and experimental dimensionless flow rates were representative of those occurring at the entrance to engine film cooling holes. The results for the ribbed passage are compared to established correlations for developed flow. Qualitative surface shear stress distributions were determined with liquid crystals. The complex distributions of heat transfer coefficient are discussed in light of the interpreted flow field.

Experimental Investigation of Heat Transfer in Two-Pass Coolant Passages With Ribs and Film Cooling Hole Ejection

“…Ekkad et al [23] used a twopass channel with 20 holes in both the upstream and downstream leg, and a SR=0. 8. It found that the extraction did not modify the area-averaged 0 / Nu Nu ratios.…”

“…It found extraction to have appreciable effects on the full surface heat transfer distribution. Shen et al [8] used a single-pass channel with five holes and with SR=1.85 to 5.07. It showed that the extraction raised the averaged heat transfer value from the 0% extraction ribbed wall by about 25%, independently of the suction ratio.…”

“…They reported considerable heat transfer coefficient variations (six times the plain duct local value) around the entrance. Shen et al [8] noted that in the presence of normal ribs, the heat transfer in the vicinity of the holes was increased by about 25%. Thurman et al [9] focused on varying bleed rates and rib placement relative to hole locations.…”

Heat transfer in a twin-blow narrow channel with two opposite walls roughened by skewed ribs arranged in staggered manner

“…In addition to the required large channel width-to-height ratios in the range of 6-10 for present application, the flow structures and heat transfer characteristics in a twin-blow narrow channel are considerably modified from the conventional single-blow scenarios. Although the heat transfer enhancement using surface ribs has been a subject of much fundamental research over the last two decades [1][2][3][4][5][6][7][8][9][10][11], no previously published work is available for the ribroughened channel with twin blow entrances. In this respect, the absence of research efforts and the need for electronic cooling in a notebook PC have motivated the present study.…”

“…Theses rib-roughened channels take varying cross-sectional shapes with a wide range of rib geometries typical of rib-angle 30 • -90 • , rib-height 0.0625-0.15 of channel-hydraulic-diameter and rib-pitch 8-30 of rib-height that are formulated as continuous, broken and V shaped with inline, staggered and criss-cross arrangements [1][2][3][4][5][6][7][8][9][10][11]. The studies of heat transfer in a rib-roughened narrow channel results in the large channel width-to-height ratio.…”