Numerical simulation and cooling performance improvement on cooling system of two type motorcycles and its comprehensive thermal management test

• 1D-3D integrated simulation method is used for analyzing motorcycles cooling system. • Performance improvement study are studied and designs are obtained. • Solid components temperatures are analyzed through fluid–solid coupling simulation. • Comprehensive thermal balance test for systematic validation is conducted. With the growing demand for high-performance motorcycles, advanced thermal management systems have become critical for ensuring engine reliability and efficiency. This study aims to evaluate and optimize the thermal performance of motorcycle cooling systems through a combined approach of computational fluid dynamics (CFD) simulations and experimental validation. A series of CFD analyses were conducted to assess cooling system compatibility, optimize airflow pathways, and analyze temperature distributions across solid components. Key design improvements included increasing the radiator width by 15 mm or height by 19.5 mm, which enhanced heat transfer efficiency and maintained coolant inlet temperatures below the 100 ℃ target. Additionally, a horizontal grille design was introduced to direct airflow downward, addressing low cooling air velocity at the cylinder head. The surface average airflow velocity on the engine head increased from 0.74 m/s in the original configuration to 1.54 m/s in the modified configuration, representing an increase of 108 %. For Motorcycle B, an optimized radiator inlet design improved airflow uniformity and reduced airflow resistance. This was achieved by adding an airflow guide structure, a radiator shield with evenly distributed openings, and by reducing the air shielding area of the fan outlet, all of which contributed to better temperature control. The surface average airflow velocity of radiator core rises from the original 6.25 m/s to 7 m/s, the increment percentage is 12 %. Temperature simulation results demonstrated that the optimized ventilation design reduced the average surface temperature of the cylinder head by 34 ℃ in Motorcycle A, while Motorcycle B exhibited uniform temperature distribution, with maximum temperatures for the engine cylinder head cover, upper crankcase, and oil pan being 90 ℃, 152 ℃, and 90 ℃, respectively, and no extensive localized hot spots present. Thermal management validation tests confirmed strong agreement between simulated and measured temperature values, particularly for the exhaust muffler, verifying the reliability of the CFD model. The water-cooled motorcycle’s thermal management system proved effective, with controlled coolant temperatures and satisfactory thermal comfort for the rider. Thermal balance tests confirmed that Motorcycle A’s modified cooling system maintains all key engine component temperatures within acceptable limits, even under high-speed, high-ambient-temperature conditions. These findings provide a theoretical and methodological foundation for performance evaluation and optimization of thermal management systems in various motorcycle types.