Effect of hydrodynamic drag and Reynolds number on friction performance for canola oil-based biolubricants

Biolubricants based on vegetable oil have gained much attention because they address lubrication issues by incorporating various additives, including inorganic and natural compounds, thereby extending their use across a wide range of applications [1,2]. This study assesses the impact of the hydrodynamic regime and the drag force on the friction performance of canola oil containing eugenol and curcumin as antioxidant additives. For that purpose, rheological assessments were previously conducted to determine the Reynolds number (Re) and the hydrodynamic drag force. Friction tests were conducted in sliding contact with a constant normal load of 0.5 N.

The measured friction force (Ff) was 0.050 N for the base oil, 0.040 N for CaO/Eugenol, and 0.045 N for CaO/Curcumin, corresponding to friction reductions of 20% and 10%, respectively, compared to the unmodified oil. The Re range obtained was 4.45 to 4.92, indicating that the biolubricants operate in a laminar flow regime. The estimated drag force remained on the order of 10⁻⁴ N, representing approximately 0.8% to 1.0% of the total friction force. Although the hydrodynamic contribution is less than the contact friction component, the results demonstrate that the lubricant's physicochemical modifications alter flow conditions and modulate the overall tribological response. Reducing frictional force directly reduces energy loss during sliding contact, indicating a potential boost in energy efficiency when these formulations are used in mechanical systems operating under similar conditions.

From a sustainability standpoint, using vegetable oil-based lubricants with naturally derived additives that improve tribological efficiency shows promise for reducing energy losses and lowering dependence on conventional mineral-based lubricants. Overall, the results suggest that balancing rheological properties and hydrodynamic behavior can help develop high-performance, environmentally friendly bio-based lubricants.

doi:10.3390/lubricants7030025 doi:10.1177/13506501221121896