Effect of topology on hybrid-linked jet impingement

Abstract

Present paper considers hybrid-linked jet impingement which involves both parallel linked jets and serial linked jets. Eight configurations with different topologies were tested under five mass flow rates ranging from 0.4 to 0.8 kg/m 2 s. The equivalent Reynolds numbers range from 12,000 to 24,000 for serial linked jets. Both heat transfer data and pressure drop data were obtained from the steady state experiments.Due to the parallel linkage, the heat transfer for the parallel jets decreases with increasing total number of parallel jets, while the heat transfer for the serial jets stay constant regardless of the change in topology. Although the serial jets are inclined, the heat transfer level of serial jets are typically higher than parallel jets due to the concentration of mass flow rate. Case 1 with purely serial linked jets shows a heat transfer enhancement by 100~150% as compared to the traditional design Case 8. However, the pressure drop of such configuration is around 20 times higher than that of the traditional designs. Analytical modelling work shows that the overall averaged heat transfer is a weighted average of [(m/A)/n] 0.4 and (m/A) 0.4 , which represents the heat transfer induced by parallel jets and serial jets respectively.

Length to diameter ratio effect on heat transfer performance of simple and compound angle holes in thin-wall airfoil cooling

“…Recently, some new blade concepts are proposed, for example, near wall cooling or double wall airfoil cooling [1] shown in Fig. 1, where small cooling cavities require impingement with low distance [2][3][4] and thinwall outer foil requires discrete film holes with short length-to-diameter ratio [5]. Due to manufacture limitations, shaped holes are difficult to use on the thin-wall airfoils, whereas simple angle and compound angle holes are suitable.…”