Motorcycle Flow And Heat Transfer Analysis Based On The Rider Thermal Comfort

Nowadays,the vehicle lightweight and comfort factors have played more and more important roles in the motorcycle development process.In relevant papers,one of a best solution for the vehicle lightweight design is to improve the heat dissipation efficiency of the cooling system.And some papers show that the engine and its cooling system are the main reasons for the poor thermal comfort of motorcycle.Some CFD amylase molds had been built successfully in this paper to analyze the water jacket cooling performance,to improve the radiator heat transform efficiency in the vehicle as well as the rider thermal comfort performance.It realizes the riding thermal comfort on the premise of the aerodynamic performance and heat dissipation capacity of the whole vehicle.The paper’s main research work and results are as below:1.Several solutions have been applied to improve the cooling performance of the original water jacket based on the CFD simulation mold.According to the simulation results,the water jacket pressure differential had reduced 46.3%,which was benefit for the vehicle performance.The mean heat transforms coefficient of the total water jacket had increased 6%,that was good for improving the engine combustion.Balance the heat dissipation of the cylinder head and cylinder block based on the motorcycle water jacket guideline,that was benefit for reduce the water temperature.2.The vehicle heat dissipation simulation results show that the air duct not only have effect on the max velocity of motorcycle,but also heat release rate of the vehicle cooling system.The motorcycle heat dissipation had improved 4% by changing the structure and the position of fender,which had little effect on vehicle aerodynamic performance(the air drag force only increase 1.5% than before).The Installation position of radiator had affected on vehicle heat dissipation(improved 13.1%)as well as the air drag force(reduce 1%).Increasing the air duct outlet area was also a good solution to help improve the vehicle heat as well as the aerodynamic.Combined with the analysis solutions above,the actual heat dissipation of the radiator is 18.5% higher than that of the original vehicle,and the air drag force had reduced 0.5Nm than the original motorcycle.3.The reasons for the poor thermal comfort of the original vehicle were explained by the CFD simulation cases.Some solutions had been applicated to improve the rider’s poor PMV value,such as changed the exhaust pipe material to reduce the radiant heat and added a radiator shroud to reduce the hot wind that blowing to the ridder directly.Although those solutions adverse to vehicle aerodynamics(increase 4.7%)and the vehicle heat dissipation(increase 7.6%).The air drag force value was no far away from the limitation,which can be accepted by engineering application.