Optimal groove design for viscous drag reduction in wet clutch lubrication to enhance energy-efficiency in power transmissions

Wet clutches are critical components in mechanical power transmission systems, enabling controlled torque transfer between rotating parts. However, when disengaged, viscous drag torque is generated, reducing the transmission efficiency. Surface texturing, particularly groove patterns, is commonly employed to modulate flow dynamics and aeration process, ultimately decreasing drag torque. Despite their practical importance, systematic approaches for optimising groove design in wet clutches remain limited in the literature. To address this gap, this study proposes an integrated experimental–Gaussian Process Regression-based, multi-objective optimisation methodology aiming to minimise cumulative power loss while maximising torque capacity. To achieve that, a single-disc test rig was designed to evaluate various groove geometries and operating conditions for the GPR model. Conventional radial grooves were benchmarked against new topologies, and exhaustive search optimisation was used to explore the design space and find the optimal solution. The findings demonstrate the potential for groove design optimisation, with quantified benefits such as up to 23% reduction in cumulative power loss for arc–bow grooves and up to 21.8% for mid-relief designs, highlighting their broader applicability in wet clutch and lubrication systems.