The internal cooling technology of gas turbine blades has been extensively used by different forced convective channels with repeated-rough ribs. The ribs act as turbulence promoters and increase the turbulent heat transfer in the fluid and the wall of the blades. Therefore, this cooling process represents a problem of conjugate heat transfer between blade shell-cooling fluid. In this work, a conjugate heat transfer model was established to numerically investigate the conjugate thermal&nbsp;performance of a&nbsp;steam-cooled ribbed channel with thick metallic walls. By employing the software of ANSYS CFX, the flow field in the channel and the temperature field in the solid channel were calculated. The&nbsp;flow behavior,&nbsp;heat transfer performance and temperature gradient distributions of ribbed channels with wall thickness&nbsp;(δ)&nbsp;of 1 -&nbsp;5 mm, rib height-to-hydraulic diameter (e/D) of 0.047&nbsp;-&nbsp;0.188, rib pitch-to-height ratio (P/e) of 5&nbsp;-&nbsp;15 and rib angle-of-attack (α) of 30°&nbsp;-&nbsp;90°&nbsp;were compared and analyzed. The optimum structure parameters of thick-wall ribbed channel with higher heat transfer performance and lower maximum temperature gradient were obtained.&nbsp;The results show that the SST k-ω&nbsp;turbulence model is more suitable for the conjugate heat transfer problem of steam in the thick-wall ribbed channels. The average Nusselt number increases up to 8.81 times, while the maximum temperature gradient decreases about 45.35% when Reynolds number varies from 10,000 to 70,000. The rib angle of about&nbsp;45°-60°, e/D&nbsp;of 0.188, and P/e&nbsp;of 10 are suitable to obtain the optimum thermal performance of steam flow in the ribbed channel through the comparative study of heat transfer and maximum temperature gradient under the same condition.&nbsp;Increasing wall&nbsp;thickness is beneficial&nbsp;to&nbsp;reduce the maximum gradient of the ribbed channel&nbsp;in spite of little influence of wall thickness on the flow and heat transfer characteristics.

Study on Conjugate Thermal Performance of a Steam-Cooled Ribbed Channel with Thick Metallic Walls

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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