Numerical Investigation of Heat Transfer in Channels Rotating Around a Parallel Axis

This study numerically investigates the effects of channel geometry and rotational speed on flow and heat transfer characteristics in channels rotating around a parallel axis. Four different channel cross-sections—circular, elliptical, square, and rectangular—were examined to evaluate their thermo-hydraulic performance. Three-dimensional numerical simulations were performed using ANSYS Fluent for rotational speeds ranging from 500 to 4000 rpm. The numerical model was validated against the experimental data of Humphreys et al. for the circular channel configuration, showing good agreement with the measured wall temperature distribution and Nusselt number. The results indicate that rotational speed significantly influences both heat transfer and friction characteristics within the channel. While the Nusselt number generally increases with increasing rotational speed due to enhanced secondary flow effects, the friction factor also rises, which reduces the overall thermo-hydraulic efficiency. Among the investigated geometries, the rectangular channel consistently exhibited the highest thermal performance factor across all rotational speeds (500–4000 rpm), reaching a maximum TPF of 1.09 at 500 rpm compared with the circular reference channel. These findings suggest that channel geometry plays a critical role in determining thermo-hydraulic performance in rotating cooling passages. In particular, rectangular channels may offer a promising design alternative for improving the thermo-hydraulic performance of rotating cooling passages used in traction motor cooling systems and similar rotating machinery applications.