Effects of axial elliptical slit on convective heat transfer and entropy generation evaluation in Taylor–Couette flow

Abstract

Improving the heat transfer of annular gap flow is essential for cooling of rotating machinery systems, but the effects of slit structures remain insufficiently studied. Therefore, filling this gap is critical for optimizing energy efficiency and reducing irreversibility in industrial applications. This study investigates the heat transfer and flow characteristics of Taylor–Couette flow with elliptical slit structure using large eddy simulations (LES). The effects of slit width (w) and number (n) on the flow and thermal properties of the annular gap flow are examined through the friction factor (f), Nusselt number (Nu), and thermal performance factor. Additionally, entropy generation analysis is employed to assess the impact of elliptical slits on energy loss and irreversibility. The results indicate that the Nu increases by a maximum of 20.66 % and 6.67 % with variations in w and n. The maximum thermal performance factors are achieved at w = 11.3 mm and n = 12 when slit width and number are increased, reaching optimum values 1.31 for Re = 4683. In the slit region, the low-velocity zone tends to form a vortex structure that inhibits fluid flow and affects temperature distribution uniformity when w > 11.3 mm. Changes in slit width lead to more significant variations in frictional and thermal entropy generation compared to slit number. The total entropy generation aligns with the variation in thermal entropy generation. This study identifies elliptical slit width as the critical parameter influencing heat transfer and irreversibility, providing valuable insights for optimizing related machinery. © 2025 Elsevier Ltd