Experimental study of flow physics and heat transfer across the matrix subchannels

• Flow physics occurring within matrix subchannels has been successfully captured. • Swirl commences at the entry, which later evolves as a full-scale streamwise vortex. • The additional corner vortices also evolved near the main vortex. • Vortices deteriorate during turning and impingement and subsequently re-develop. • The impingement is found to enhance the turbulence and heat transfer significantly. Matrix or latticework cooling is commonly known for offering an excellent heat transfer performance and structural strength to modern gas turbine’s blades. Detailed fluid flow studies inside matrix subchannels are still very limited, mainly due to experimental challenges. This work is a forward step in this theme in which particle image velocimetry (PIV) and Liquid Crystal Thermography (LCT) is used to capture the complex flow patterns and heat transfer across the matrix subchannels at Reynolds numbers 800 and 6500. The outcome of the study shows that a swirl commences at the entry of subchannels, which evolves in terms of a full-scale streamwise vortex in downstream. The evolved vortical structures deteriorate during turning and impingement and subsequently re-develop while propagating through subchannels. Mean turbulent kinetic energy ( k ¯ ) distribution shows that turning and impingement offer a sharp turbulence augmentation. i.e. , the k ¯ values after first turn shows an increment of ∼175 % (for Re = 800) and ∼100 % (for Re = 6500). The average augmentation Nusselt number ( Nu N u 0 ¯ ) is found to closely correlated with k ¯ , consequently the first turning offers an increment ∼125 % ( Re = 800) and ∼200 % ( Re = 6500) in Nu N u 0 ¯ .