Enhancing heat transfer in a rotating droplet-shaped pin-fins channel: Investigating the influence of rotational radius ratio and temperature ratio

A droplet -shaped pin -fins array is designed to optimize the heat transfer coefficient (HTC) in the trailing edge channel of turbine blades. Experimental testing was conducted under a wide range of conditions, including varying inlet Reynolds numbers (Re) ranging from 10,000 to 70,000, rotation numbers (Ro) from 0 to 1.0, temperature ratios (TR) from 0.04 to 0.22, rotational radius ratios (r/D) from 25.67 to 52.33, and Buoyancy numbers (Buo) from 0 to 2.55. The study reveals a significant increase in convective heat transfer on the trailing surface (TS) under rotational conditions, indicating enhanced heat transfer characteristics. Conversely, rotation negatively affects heat transfer on the leading surface (LS), reducing its effectiveness. Rotation accelerates fluid velocity near the TS of the radial outflow channel due to the Coriolis force, and causes cooler secondary flow fluid to impact the TS. HTC gradually decreases with rising TR at different dimensionless positions. The impact of r/D on HTC is also analyzed, showing a 10 % increase in average Nusselt numbe at a r/D of 52.33 compared to 25.67 at Re of 5,000. When Re, Ro, and Buo are kept constant, there is a significant approximately 20.8 % variation in the level of heat transfer, despite changes in TR and r/D. Maintaining consistent dimensionless parameters such as Re, Ro, Buo, TR, r/D, D is crucial for accurate HTC. These findings provide valuable insights for optimizing the understanding of HTC in internal cooling channels.