An Experimental Study of Barchan-Dune-Shaped Injection Compounds for Improved Film Cooling Effectiveness

Abstract

Inspired by the unique shape of a Barchan dune to prevent sand particles on the ground from being blown away by the oncoming airstream, we proposed a Barchan-duneshaped injection compound (BDSIC) for film cooling. Similar as the sand particles settling down on the ground behind the dune, the coolant streams exhausted from the BDSIC would be able to cover on the surface of interest more widely. The film cooling performance behind the BDSIC had been studied experimentally for a single 35 degree angled hole on a flat plate using the PSP and PIV techniques. The effects of dune shape (shorted, normal, and elongated dune), mass flux ratio (M=0.6, 0.9, 1.2, 1.5), density ratio (DR=0.97, 1.5, 2.1), and hole interaction on the film cooling effectiveness were studied in great detail. It was found that the BDSIC configurations can significantly enhance the film cooling effectiveness of baseline for all test conditions, especially the BDSIC with elongated dune. In addition, the aerodynamic loss study revealed that the turbulent mixings of the BDSIC between jet and mainstream were largely alleviated at relative high mass flux ratios. All in all, the BDSIC concept exhibits the merits from both Barchan dune and ideal tangential slot, demonstrated an enhanced cooling effectiveness with less aerodynamic loss.